Maternal prepartum supplementation of protein and energy and body condition score modulated the performance of Bos indicus-influenced cow-calf pairs

Retrospective analyses were performed on a dataset of 1188 fall-calving, Brangus cow-calf pairs. Analyses 1 sorted cows according to their initial body condition score (BCS < 5 vs. ≥ 5) and whether they received (SUP) or not (NOSUP) prepartum supplementation of protein and energy. Analyses 2 sorted cows according to their calving BCS (BCS < 5 or ≥ 5) and BCS change from calving until the start of the breeding season (lost, maintained, or gained). Cows were not estrus synchronized and were assigned to natural breeding for 90 days. Prepartum supplementation increased (P = 0.04) pregnancy percentage in cows with initial BCS < 5 but not (P = 0.20) with initial BCS ≥ 5. Calf weaning weight was greatest (P ≤ 0.04) for calves born from SUP cows with an initial BCS ≥ 5 and did not differ (P ≥ 0.56) among all remaining groups. Among cows with calving BCS < 5, pregnancy percentage were less (P = 0.05) for cows that lost vs. maintained/gained BCS. Postpartum BCS change did not (P ≥ 0.16) impact pregnancy percentage of cows calving at BCS ≥ 5. Calf weaning weight increased (P < 0.01) for cows calving with BCS ≥ 5 vs. < 5 and was not impacted (P = 0.47) by postpartum BCS change. Therefore, precalving supplementation improved reproduction of cows with BCS below optimal and weaning weight of calves born from cows with BCS above optimal, whereas calving BCS was the major factor affecting postpartum BCS change and cow reproductive performance.

Effect of Different Herbage Allowances from Mid to Late Gestation on Nellore Cow Performance and Female Offspring Growth until Weaning

This study evaluated different herbage allowances from mid to late pregnancy on pre- and postpartum physiological responses, milk production, and the performance of Nellore cows and the preweaning growth of their female offspring. Sixty multiparous Nellore cows were blocked by their body weight (BW; 425 ± 36 kg) and body condition score (BCS; 3.67 ± 0.23, scale 1-5) and randomly allocated to twelve pastures. Treatments consisted of two different herbage allowances (HA) during pregnancy: low HA (LHA; 2.80 kg DM/kg of BW) and high HA (HHA; 7.60 kg DM/kg of BW). Both treatment groups were fed 1 g/kg BW of a protein supplement. After calving, all cow-calf pairs were combined in a single group. The effects of maternal treatment × day of the study were detected for herbage mass and allowance, the stocking rate and forage crude protein, and for cow BW, BCS, and carcass measures (p < 0.01). Milk yield corrected to 4% fat, while the levels of fat total solids and cow plasma IGF-1 and urea were different (p ≤ 0.04) between treatments. HHA offspring was heavier (p ≤ 0.05) at 120 days and at weaning. A high herbage allowance can be implemented from mid-gestation until calving to increase cow prepartum performance, post-partum milk yield and composition, and positively modulate female offspring preweaning growth.

Maternal pre- and postpartum supplementation of a Bacillus-based DFM enhanced cow and calf performance

This study evaluated the effects of maternal supplementation of a Bacillus-based direct-fed microbial (DFM) on the physiology and growth performance of Bos indicus-influenced cow-calf pairs. On day 0 (~139 d before expected calving date), 72 fall-calving, Brangus crossbred beef heifers (20 to 22 mo of age) pregnant with first offspring were stratified by their initial body weight (BW; 431 ± 31 kg) and body condition score (BCS; 6.0 ± 0.36; scale 1 to 9), and randomly allocated into 1 of 12 bahiagrass pastures (1 ha and six heifers per pasture). Treatments were randomly assigned to pastures (six pastures per treatment) and consisted of heifers supplemented with 1 kg/d of soybean hulls (dry matter, DM) that was added (BAC) or not (CON) with DFM containing Bacillus subtilis and B. licheniformis (Bovacillus; Chr. Hansen A/S, Hørsholm, Denmark). Treatments were provided from days 0 to 242 (139 ± 4 d prepartum to 104 ± 4 d postpartum). Calves were weaned on day 242 (96 ± 30 d of age) and then allocated into 1 of 16 drylot pens and fed the same concentrate at 3.25% of BW (DM) until day 319. Maternal treatment effects were not detected (P ≥ 0.29) for herbage allowance and forage chemical composition. Heifer BCS on days 39 and 63 tended (P ≤ 0.09) to be greater for BAC vs. CON heifers, whereas heifer BCS on day 91 was greater (P = 0.01) for BAC vs. CON heifers. Heifer BCS did not differ (P ≥ 0.20) between treatments on days 179 and 242. Plasma glucose concentration did not differ from days 0 to 63 (P ≥ 0.14) but were greater (P < 0.01) on day 179 and tended (P = 0.09) to be greater on day 242 for BAC vs. CON heifers. Calf BW at birth, ADG from birth to weaning, and BW at weaning did not differ (P ≥ 0.19) between treatments, but calf BW at drylot exit (day 319) was greater (P = 0.05) for BAC vs. CON calves. Maternal treatment effects were not detected (P ≥ 0.42) for calf serum concentration of IgG at birth and postvaccination plasma concentrations of glucose, cortisol, and haptoglobin. Serum titers against bovine respiratory syncytial virus (BRSV) were greater (P = 0.04) for BAC vs. CON calves on day 287, whereas seroconversion against parainfluenza-3 virus (PI-3) was greater (P < 0.01) for BAC vs. CON calves on day 271. Thus, maternal supplementation of a Bacillus-based DFM increased prepartum BCS gain and postpartum plasma glucose concentration of heifers and led to positive carryover effects on postweaning BW gain and humoral immune response in their offspring.

Early Weaning Possibly Increases the Activity of Lipogenic and Adipogenic Pathways in Intramuscular Adipose Tissue of Nellore Calves

This study aimed to evaluate by wide-expression profile analysis how early weaning at 120 days can alter the skeletal muscle metabolism of calves supplemented with a concentrated diet until the growth phase. Longissimus thoracis muscle samples were obtained by biopsy from two groups of calves, early weaned (EW; n = 8) and conventionally weaned (CW; n = 8) at two different times (120 days of age-T1 [EW] and 205 days of age-T2 [CW]). Next, differential gene expression analysis and functional enrichment of metabolic pathways and biological processes were performed. The results showed respectively 658 and 165 differentially expressed genes when T1 and T2 were contrasted in the early weaning group and when early and conventionally weaned groups were compared at T2. The FABP4, SCD1, FASN, LDLR, ADIPOQ, ACACA, PPARD, and ACOX3 genes were prospected in both comparisons described above. Given the key role of these differentially expressed genes in lipid and fatty acid metabolism, the results demonstrate the effect of diet on the modulation of energy metabolism, particularly favoring postnatal adipogenesis and lipogenesis, as well as a consequent trend in obtaining better quality cuts, as long as an environment for the maintenance of these alterations until adulthood is provided.

Fire management effects on ruminal digestibility and in vitro methane emissions of subtropical rangeland plant species

Prescribed fire is a common management practice used to manipulate rangeland plant productivity and composition. Although the nutritive value of most herbaceous plant species is considered poor for grazing animals, native rangelands in Florida are an important source of forage for livestock, especially during the winter months, when the productivity of cultivated perennial warm-season pastures is limited. This study evaluated the effects of prescribed fire on methanogenic potential and nutritive value of selected native rangeland plant species. Treatments were a 3 × 2 factorial arrangement of plant species (creeping bluestem [Schizachyrium scoparium var. stoloniferum {Nash} Wipff], wiregrass [Aristida stricta {Michx.}], or saw palmetto [Serenoa repens {W. Bartram} Small]) and prescribed fire management [2 yr after burning (control) vs. 1 yr after burning (burned)] distributed in a randomized complete block design with four replicates. Samples were analyzed for crude protein (CP), neutral detergent undigestible fiber (NDF), in vitro methane production, and in situ ruminal disappearance. Prescribed fire generally increased forage CP and DM effective degradability relative to control; however, no effect was observed on saw palmetto. Wiregrass had the least CP concentration in both burned (8.5%) and control (2.3%). In burned treatments, creeping bluestem and palmetto had greater DM effective degradability (62% and 58%) than wiregrass (53%). Fire increased in vitro gas production by 60 (creeping bluestem) to 90% (wiregrass) relative to control treatments. No effect of fire on methane production was observed for any of the plant species evaluated in this study. Creeping bluestem had the greatest methane production (12.5 mg/g DM), followed by wiregrass (5.3 mg/g DM) and saw palmetto (1.4 mg/g DM). Methane:DM effective degradability decreased in the following order: creeping bluestem ≥ wiregrass > saw palmetto. Data indicated prescribed fire was an effective tool to increase creeping bluestem and wiregrass nutritive value but no effect was observed on saw palmetto. Cattle grazing grass-dominated rangelands will likely emit more gas and methane than shrub or tree-dominated ecosystems; however, the greater forage nutritive value and subsequent positive impacts on animal production are expected to offset a substantial fraction of enteric methane emissions.

Removing maternal heat stress abatement during gestation modulated postnatal physiology and improved performance of Bos indicus-influenced beef offspring

This study evaluated the growth and immune response of beef calves born from Bos indicus-influenced beef heifers provided pre- and postpartum heat abatement on pasture. On 83 ± 4 d prepartum (day 0), 64 Brangus crossbred beef heifers (~¼ B. indicus) were stratified by body weight (BW; 454 ± 37 kg) and body condition score (BCS; 6.3 ± 0.28; scale 1 to 9), and then allocated into 1 of 16 bahiagrass pastures (1 ha and 4 heifers per pasture). Treatments were randomly assigned to pastures (8 pastures per treatment) and consisted of heifers provided (SH) or not (NSH) access to artificial shade (4.5 m2 of shade area per heifer) from 83 d prepartum to 50 d postpartum (days 0 to 133). Heifers and calves were managed similarly from day 133 until the start of the breeding season (day 203). Calves were weaned on day 203 (at 119 ± 19 d of age), limit-fed the same drylot diet at 3.5% of BW (DM basis) days 209 to 268 (3 to 4 calves per pen; 8 pens per treatment) and vaccinated against respiratory disease pathogens on days 222 and 236. Heifer intravaginal temperatures from days 35 to 42 were lower (P ≤ 0.03) for NSH vs. SH heifers from 0000 to 0800 hours but greater (P ≤ 0.05) for NSH vs. SH heifers from 1100 to 1800 hours. Heifer intravaginal temperature from days 126 to 132 did not differ (P = 0.99) between NSH and SH heifers. Heifers assigned to NSH had greater respiration rates from days 20 to 96 (P ≤ 0.0007), greater plasma concentration of cortisol on days 35 (P = 0.07) and 55 (P = 0.02), less plasma concentration of insulin-like growth factor 1 (IGF-1) on days 35 (P = 0.10), 55, and 133 (P ≤ 0.05), and less BCS from days 55 to 203 (P ≤ 0.01) compared to SH heifers. Calves born from NSH heifers had less birth BW (P = 0.05), greater overall plasma haptoglobin concentrations (P = 0.05), greater seroconversion against bovine respiratory syncytial virus on day 222 (P = 0.02), tended to have greater ADG from days 209 to 268 (P = 0.07), and had greater BW on day 268 (P = 0.05) compared to SH offspring. Plasma concentrations of cortisol and serum titers against other respiratory disease pathogens did not differ (P ≥ 0.15) between NSH and SH offspring. Hence, removing maternal access to artificial shade: (1) increased prepartum intravaginal temperature and plasma concentrations of cortisol but reduced prepartum BCS and plasma concentrations of IGF-1 in grazing B. indicus-influenced beef heifers; and (2) increased post-weaning BW gain and had positive effects on humoral immune response of their offspring.

Bakery waste supplementation to late gestating Bos indicus-influenced beef cows successfully impacted offspring postnatal performance

This study evaluated the growth and immune function of beef calves born to cows supplemented with bakery waste containing two concentrations of crude fat. On day 0 (~90 d before calving), 108 multiparous Brangus crossbred cows were stratified by body weight (BW; 551 ± 65 kg) and body condition score (BCS, 5.5 ± 0.9) and randomly allocated into 1 of 18 bahiagrass (Paspalum notatum) pastures (6 cows and 4.3 ha per pasture). Treatments were randomly assigned to pastures (6 pastures per treatment) and consisted of no prepartum supplementation (NOSUP) and isocaloric and isonitrogenous supplementation of low-fat (LFAT; 6.4% crude fat) or high-fat (HFAT; 10.7% crude fat) bakery waste from days 0 to 70 (1 kg DM per cow per day). Calves were weaned on day 292 (201 ± 17 d of age). Then, 15 heifers per treatment were randomly selected and assigned to drylot pens from days 300 to 345 and vaccinated against respiratory pathogens on days 300 and 315. Cow BCS near calving (day 70) was the least (P ≤ 0.05) for NOSUP cows and did not differ (P = 0.12) between LFAT and HFAT cows. Cow BCS at the start of the breeding season (day 140) was greater (P = 0.05) for HFAT vs. NOSUP cows and intermediate (P ≥ 0.35) for LFAT cows. Plasma concentrations of total polyunsaturated fatty acids in HFAT cows did not differ (P ≥ 0.76) compared with LFAT cows but were greater (P ≤ 0.05) compared to NOSUP cows on day 70. Final pregnancy percentage did not differ (P ≥ 0.26) among treatments, but a greater percentage of HFAT cows calved (P ≤ 0.05) their second offspring during the first 21 d of the calving season compared to NOSUP and LFAT cows (bred by natural service). Weaning BW was the greatest (P ≤ 0.05) for LFAT and least for NOSUP calves. Maternal treatments did not impact (P ≥ 0.11) postweaning growth and total DM intake of calves. Average plasma cortisol concentrations were greater (P = 0.03) for NOSUP vs. HFAT calves and intermediate for LFAT calves (P ≥ 0.26). Serum titers against infectious bovine rhinotracheitis and bovine respiratory syncytial virus were greater or tended to be greater (P ≤ 0.08) for HFAT vs. LFAT calves and intermediate (P ≥ 0.27) for NOSUP calves at the end of preconditioning. Thus, supplemental fat concentration fed to late-gestating beef cows had variable effects on calf performance. Low-fat bakery waste led to the greatest calf preweaning growth, whereas high-fat bakery waste enhanced maternal reproduction and had minor benefits to calf humoral immune function.

PSIV-A-7 Decreasing the Frequency of Precalving Protein and Energy Supplementation Impacts Preweaning Growth of Bos Indicus-Influenced Beef Offspring but not Their dam

This experiment evaluated the impacts of frequency of dried distillers grains (DDG) supplementation during late gestation on subsequent performance of cow-calf pairs. On day 0 (September), 120 multiparous Brangus cows (body weight, BW = 543 ± 4.6 kg; body condition score, BCS = 5.47 ± 0.09) were allocated into 1 of 20 bahiagrass pastures (6 cows and 4.7 ha/pasture). Treatments were assigned randomly to pastures (5 pastures/treatment) and consisted of cows offered no DDG supplementation (NOSUP), 1 kg/cow of DDG daily (7X), 2.33 kg/cow of DDG every Monday, Wednesday, and Friday (3X), or 7 kg/cow of DDG every Monday from day 0 to 77 (1X; total of 77 kg/cow of DDG dry matter for all supplemented cows). After calving (on average day 81 ± 7), all cow-calf pairs were managed similarly and remained on their respective pasture until calf weaning (day 342). Cow BW did not differ among treatments (P ≥ 0.13). Cow BCS on day 77 and at the start of the breeding season (day 140) were greater for supplemented vs. NOSUP cows (P ≤ 0.02) but did not differ among 1X, 3X and 7X cows (P ≥ 0.64). Overall plasma concentrations of glucose were greater for supplemented vs. NOSUP cows (P ≤ 0.05) but did not differ among 1X, 3X and 7X cows (P ≥ 0.44). Calving percentage, calving date, percentage of male calves at birth, and calf birth BW did not differ among treatments (P ≥ 0.15). Calf BW at weaning were lowest for NOSUP and greatest for 7X calves (P ≤ 0.05). Calf BW at weaning did not differ between 1X and 3X calves (P = 0.97) and both groups were intermediate (P ≤ 0.05). In summary, decreasing the frequency of DDG supplementation during late gestation did not impact pre- and post-partum performance of Bos indicus-influenced beef cows but reduced subsequent preweaning growth of their offspring.

310 Effects of Stair Step Strategy and Immunomodulatory Feed Ingredient Supplementation on Thermoregulation, Growth, and Reproduction of Grazing Bos Indicus-Influenced Beef Heifers

This 2-yr study evaluated the combination of stair step supplementation strategy and OmniGen-AF inclusion on body thermoregulation, growth, and reproduction of Bos indicus-influenced beef heifers. Brangus heifers (n = 64/year) were stratified by BW and age (257 ± 20 kg; 271 ± 22 d) and allocated into 16 bahiagrass pastures. Treatments were randomly assigned to pastures in a 2×2 factorial arrangement. Treatments consisted of concentrate dry matter (DM) supplementation at 1.50% of BW from day 0 to 100 (CON) or concentrate DM supplementation at 1.05% of BW from day 0 to 49 and 1.95% of BW from day 50 to 100 (SST), which included or not OmniGen-AF from day 0 to 100 (OMN; 4 g/45 kg of BW). Heifers were submitted to an estrus synchronization protocol from day 100 to 114, inseminated from day 112 to 114, and exposed to bulls from day 120 to 210. Data were analyzed using SAS GLIMMIX procedure. Heifer BW did not differ (P ≥ 0.49) on days 0 and 56, but on days 100 and 210 it was greater (P ≤ 0.01) for SST vs. CON. Intravaginal temperatures from day 26 to 30, between 0830 and 1600h were least (P ≤ 0.03) for SST offered OMN and did not differ (P ≥ 0.17) among all remaining treatments. Body surface temperature on day 25 and plasma IGF-1 concentrations on day 75 were greater (P ≤ 0.04) for SST vs. CON. Percentage of pubertal heifers, estrus detection, and pregnancy to AI did not differ (P = 0.36) between SST and CON, but final pregnancy percentage was greater (P = 0.04) for SST. Thus, OMN decreased intravaginal temperature of SST heifers but failed to improve their growth and reproduction, whereas the stair step strategy improved body thermoregulation, growth, and final pregnancy percentage of Bos indicus-influenced beef heifers.

87 Awardee Talk: Frequency of Energy Supplementation Modulates Growth, Reproduction, Immune Function, and Fetal Programming in Beef Cattle

Fluctuations in nutrient intake and metabolism can be detrimental to beef cattle performance. Multiple studies evaluated the impacts of reducing the frequency of energy supplementation from daily (7X) to once (1X) or 3 times (3X) weekly during heifer development, calf preconditioning, and late gestation of beef cows on growth, reproduction, immune function, and progeny performance. Reducing the supplementation frequency from 7X to 3X weekly: (1) did not impact average daily gain (ADG; P = 0.52) but hastened (P ≤ 0.05) puberty and pregnancy attainment of beef heifers; and (2) reduced ADG (P = 0.02), increased (P ≤ 0.03) plasma indicators of physiological stress (cortisol and haptoblogin), and decreased (P ≤ 0.05) humoral immune response against pathogens associated with bovine respiratory disease (BRD) in preconditioning beef steers. Reducing the supplementation frequency from 7X to either 3X or 1X weekly during late gestation did not (P ≥ 0.21) impact cow prepartum body condition score and reproduction, but linearly decreased (P = 0.05) calf preweaning growth. The negative effects of infrequent energy supplementation may be attributed to greater fluctuations in plasma concentrations of insulin growth factor-1, glucose, insulin, and urea nitrogen compared to frequent energy supplementation. Later attempts to offset such negative effects of infrequent supplementation observed that neither increasing the supplementation amount (P ≥ 0.21) nor altering the timing of vaccination relative to weaning (P ≥ 0.12) prevented performance reductions in beef cattle supplemented infrequently. Only a gradual reduction in supplementation frequency for preconditioning calves prevented a reduction on growth and improved (P ≤ 0.05) the immune response against BRD pathogens. Combined, these results revealed that frequent energy supplementation during preconditioning of beef steers, development of replacement beef heifers, and late gestation of beef cows was required to optimize their growth, immunity, and reproduction, and the growth performance of their progeny.

PSVI-1 Effects of Rumen-Protected Methionine on Reproduction and Body Temperature of Nelore Cows in hot and Humid Environments

This study aimed to evaluate the effects of dietary supplementation of rumen-protected methionine (RPM) on the body temperature and conception rate of Nelore cows exposed to high temperature and humidity index (THI) values. This study was realized on a commercial beef farm located in the north of Brazil (5º 31’ 39” S, 48º 49’ 18” W). At d-31, 31 days before the FTAI protocol, a total of 563 lactating multiparous Nelore cows were divided into two treatments, with three blocks each, the control group (CG) and methionine group (MG). Both groups were kept on tropical pastures and received a mineral supplement. The MG Group was supplemented with 3g RPM/100g during 77 days, and the expected mineral supplement intake of both groups was 100g/cow/day. Between d0 and d9 of the FTAI protocol, a subset of groups of cows (n=142) remained with a data logger attached to the progesterone device, to monitor intravaginal temperature (IT) every 30 min. During the period that the cows remained with the dataloggers the minimum, average, and maximum THI were 72.76, 78.02, and 83.28, respectively. Pregnancy diagnosis was realized 35 days after the artificial insemination and the conception rate was calculated as the number of pregnant cows/inseminated cows. Data were analyzed using the JMP GLIMMIX procedure. RPM supplementation did not affect the conception rate (CG = 64.36% vs. MG = 58.19%, P &gt;0.05). Intravaginal temperature from day 1 to day 8, between 0630 and 2030 h and between 2200 and 0100 h were lower (P≤0.05) for MG in comparison with CG. The average and the maximum IT were, respectively, 38.94ºC, 40.88ºC for MG and 39.02ºC, and 41.38ºC for CG. In conclusion, the supplementation of rumen-protected methionine reduced the internal body temperature in Nelore cows submitted to high THI environments, during the hottest hours of the day, but does not affect the conception rate.

Frequency of maternal supplementation of energy and protein during late gestation modulates preweaning growth of their beef offspring

This study evaluated the effects of decreasing the frequency of dried distillers grains (DDG) supplementation during third trimester of gestation on cow physiology and offspring preweaning growth. At 201 ± 7 d prepartum (day 0 of the study), 120 Brangus crossbred cows were stratified by body weight (BW = 543 ± 53 kg) and body condition score (BCS = 5.47 ± 0.73), and then assigned randomly to 1 of 20 bahiagrass (Paspalum notatum) pastures (six cows and 4.7 ha/pasture). Treatments were randomly assigned to pastures (five pastures/treatment) and consisted of cows offered no DDG supplementation (NOSUP) or precalving supplementation of DDG dry matter at 1 kg/cow daily (7×), 2.33 kg/cow every Monday, Wednesday, and Friday (3×), or 7 kg/cow every Monday (1×) from day 0 to 77. All cows assigned to DDG supplementation received the same total amount of DDG dry matter (77 kg/cow) from day 0 to 77. All cow-calf pairs were managed similarly from day 77 until calf weaning (day 342). Supplementation frequency did not impact (P ≥ 0.16) any forage or cow reproduction data. Cow BCS on days 77, 140, and 342 did not differ among 1×, 3×, and 7× cows (P ≥ 0.29) but all supplemented cows, regardless of supplementation frequency, had greater BCS on days 77, 140, and 342 compared to NOSUP cows (P ≤ 0.04). Cows offered 1× supplementation had greater plasma concentrations of IGF-1 on days 35 and 140 compared to NOSUP, 3× and 7× cows (P ≤ 0.04), whereas 3× and 7× cows had greater plasma concentrations of IGF-1 on day 35 compared to NOSUP cows (P ≤ 0.005). Average plasma concentrations of glucose did not differ among 1×, 3×, and 7× cows (P ≥ 0.44), but all supplemented cows had greater plasma concentrations of glucose compared to NOSUP cows (P ≤ 0.05). Birth BW of the first offspring did not differ between 3× and 7× calves (P = 0.54) but both groups were heavier at birth compared to NOSUP calves (P ≤ 0.05). On day 342, calves born from 7× cows were the heaviest (P ≤ 0.05), whereas calves born from 1× and 3× cows had similar BW (P = 0.97) but both groups were heavier compared to calves born from NOSUP cows (P ≤ 0.05). In summary, decreasing the frequency of DDG supplementation, from daily to one or three times weekly, during third trimester of gestation of beef cows did not impact cow BCS but altered maternal plasma concentrations of IGF-1 and glucose, leading to reduced offspring preweaning growth.

Monensin supplementation during late gestation of beef cows alters maternal plasma concentrations of insulin-like growth factors 1 and 2 and enhances offspring preweaning growth

This study evaluated the effects of maternal prepartum supplementation of dried distillers grains (DDG), with or without monensin addition, on maternal performance and physiology and offspring preweaning growth. On day 0 (approximately 197 ± 4 d prepartum), 150 multiparous, Brangus crossbred beef cows were ranked by their initial body weight (BW; 524 ± 51 kg) and body condition score (BCS; 5.0 ± 0.63), and then randomly assigned into one of 15 bahiagrass (Paspalum notatum) pastures (10 cows and 8.1 ha/pasture). Maternal treatments were randomly assigned to pastures (5 pastures/treatment) and consisted of no prepartum supplementation of DDG (NOSUP) or supplementation of DDG at 1 kg/cow/d (dry matter basis; DM) added with 0 mg (SUP) or 200 mg/d of monensin (SUPMO) from days 0 to 77. Effects of maternal treatment and maternal treatment × day of the study were not detected (P ≥ 0.63) for any forage data. Cow BCS on day 35 and near calving (day 77) did not differ (P ≥ 0.19) between SUP and SUPMO cows but both groups had greater (P ≤ 0.001) BCS compared with NOSUP cows. Cow BCS at the start of the breeding season (day 142) and on day 168 were the greatest (P < 0.0001) for SUPMO cows, least for NOSUP cows, and intermediate (P ≤ 0.02) for SUP cows. Maternal plasma concentrations of glucose did not differ (P ≥ 0.25) among treatments. Plasma concentrations of insulin-like growth factor 1 (IGF-1) on day 77 were the least for NOSUP cows (P ≤ 0.05) and did not differ (P = 0.66) between SUP and SUPMO cows, whereas plasma concentrations of IGF-2 on days 35 and 77 were greatest (P ≤ 0.05) for SUPMO cows and did not differ (P ≥ 0.60) between NOSUP and SUP cows. Birth BW of first offspring did not differ (P = 0.77) between SUP and SUPMO calves but NOSUP calves were lighter at birth (P ≤ 0.05) compared with SUP and SUPMO calves. Percentage of cows pregnant with a second offspring did not differ (P = 0.72) between SUP and SUPMO cows and were the least for NOSUP cows (P ≤ 0.05). First offspring BW at weaning (day 325) was greatest (P ≤ 0.05) for SUPMO calves, least for NOSUP calves, and intermediate for SUP calves. Therefore, adding monensin into prepartum DDG supplements for Bos indicus-influenced beef cows did not increase cow prepartum BCS but led to greatest offspring preweaning growth, likely by modulating maternal plasma concentrations of IGF-1 and IGF-2 during gestation.

Stair step strategy and immunomodulatory feed ingredient supplementation for grazing heat-stressed Bos indicus-influenced beef heifers

On day 0 of year 1 and 2, sixty-four Brangus crossbred heifers per year were stratified by initial body weight (BW) and age (mean = 257 ± 20 kg and 271 ± 22 d) and allocated into 16 bahiagrass (Paspalum notatum) pastures (4 heifers/pasture/yr). Treatments were randomly allotted to pastures in a 2 × 2 factorial arrangement of treatments (4 pastures/treatment/yr). Treatments consisted of concentrate dry matter (DM) supplementation at 1.50% of BW from day 0 to 100 (CON) or concentrate DM supplementation at 1.05% of BW from day 0 to 49 and 1.95% of BW from day 50 to 100 (SST). Then, each respective supplementation strategy was added or not with immunomodulatory feed ingredient from day 0 to 100 (OMN; 4 g/45 kg of BW). Heifers were assigned to an estrus synchronization protocol from day 100 to 114. Heifers detected in estrus from day 111 to 114 were inseminated (AI) 12 h after estrus detection. Heifers not detected in estrus were timed AI on day 114. All heifers were exposed to Angus bulls from day 120 to 210 (1 bull/pasture). Effects of supplementation strategy × OMN inclusion × hour were detected (P < 0.0001) only for intravaginal temperature from day 26 to 30, which were the least (P ≤ 0.03) for SST heifers offered OMN supplementation and did not differ (P ≥ 0.17) among all remaining treatments from 0830 to 1600 h. Effects of supplementation strategy × OMN inclusion and OMN inclusion were not detected (P ≥ 0.12) for any variable, except for percentage of heifers detected in estrus, which was greater (P = 0.01) for heifers supplemented with vs. without OMN. Total concentrate DM offered from day 0 to 100 and heifer BW on days 0 and 56 did not differ (P ≥ 0.49) between CON and SST heifers, but SST heifers were heavier (P ≤ 0.01) on days 100 and 210 compared to CON heifers. Body surface temperature on day 25 and plasma IGF-1 concentrations on day 75 were greater (P ≤ 0.04) for SST vs. CON heifers. Percentage of pubertal heifers, heifers detected in estrus, and pregnancy to AI did not differ (P = 0.36) between SST and CON heifers but final pregnancy percentage was greater (P = 0.04) for SST vs. CON heifers. Thus, OMN supplementation decreased intravaginal temperature of SST heifers but failed to improve their growth and reproduction, whereas the SST strategy improved body thermoregulation, growth, and final pregnancy percentage of heat stressed Bos indicus-influenced beef heifers compared to a constant concentrate supplementation strategy.

Effects of maternal winter vs. year-round supplementation of protein and energy on postnatal growth, immune function, and carcass characteristics of Bos indicus-influenced beef offspring

This 2-yr study evaluated the effects of winter vs. year-round supplementation of Bos indicus-influenced beef cows on cow reproductive performance and impact on their offspring. On day 0 of each year (approximately day 122 ± 23 of gestation), 82 to 84 mature Brangus cows/yr were stratified by body weight (BW; 475 ± 67 kg) and body condition score (BCS; 4.85 ± 0.73) and randomly assigned to 1 of 6 bahiagrass (Paspalum notatum) pastures (13 to 14 cows/pasture). Treatments were randomly assigned to pastures consisting of winter supplementation with molasses + urea (WMOL), or year-round supplementation with molasses + urea (YMOL) or wheat middling-based range cubes (YCUB). Total yearly supplement DM amount was 272 kg/cow and supplements were formulated to be isocaloric and isonitrogenous (75% TDN and 20% CP). On day 421 (weaning; approximately 260 ± 24 d of age), 33 to 35 steers/yr were vaccinated against parainfluenza-3 (PI3) and bovine viral diarrhea virus type 1 (BVDV-1) and transported 1,193 km to a feedlot. Steers were penned according to maternal pasture and managed similarly until slaughter. Data were analyzed using the MIXED and GLIMMIX procedures of SAS. On day 217 (start of breeding season), BCS was greater (P = 0.01) for YMOL than WMOL cows, whereas BCS of YCUB did not differ (P ≥ 0.11) to both WMOL and YMOL cows. The percentage of cows that calved, calving date, birth BW, and preweaning BW of the first offspring did not differ (P ≥ 0.22) among maternal treatments. Plasma cortisol concentrations were greater (P ≤ 0.001) for YCUB steers at feedlot arrival (day 422) than WMOL and YMOL steers. Moreover, YCUB steers had greater (P = 0.02) and tended (P = 0.08) to have greater plasma concentrations of haptoglobin compared to WMOL and YMOL steers, respectively. Antibody titers against PI3 and BVDV-1 viruses did not differ (P ≥ 0.25) among maternal treatments. Steer BW at feedlot exit was greater (P ≤ 0.05) for YMOL and WMOL than YCUB steers. However, feedlot DMI did not differ (P ≥ 0.37) by maternal treatment. Hot carcass weight, yield grade, LMA, and marbling did not differ (P ≥ 0.14) among maternal treatments. Percentage of steers that graded low choice was enhanced (P ≤ 0.05) for WMOL and YCUB than YMOL steers. Maternal year-round supplementation of range cubes or molasses + urea either did not impact or decrease growth, immune function, and carcass characteristics of the offspring when compared with maternal supplementation of molasses + urea during winter only.

Timing of maternal supplementation of dried distillers grains during late gestation influences postnatal growth, immunocompetence, and carcass characteristics of Bos indicus-influenced beef calves

This 2-yr study investigated the timing of dried distillers grains (DDG) supplementation during the third trimester of gestation of Bos indicus-influenced beef cows and its impact on their offspring performance. On day 0 of each year (84 d before calving), Brangus cows (n = 84/yr; cow age = 8 ± 3 yr) were stratified by initial body weight (BW; 482 ± 75 kg) and body condition score (BCS; 5.3 ± 0.8) and assigned randomly to one of six bahiagrass (Paspalum notatum) pastures (experimental units; 14 cows/pasture). Treatments were assigned randomly to pasture (2 pastures/treatment/yr) and consisted of no prepartum supplementation (CON), 2 kg/d of DDG from day 0 to 42 (LATE42), or 1 kg/d of DDG from day 0 to 84 (LATE84). Following calving (day 84), cow-calf pairs remained in their respective pastures, and cows were offered sugarcane molasses + urea (1.82 kg of dry matter/cow/d) from day 85 until the end of the breeding season (day 224). On day 347, steer calves (n = 38/yr; 11 to 15 steers/treatment/yr) were weaned and transported to the feedlot (1,193 km). Steers were penned according to cow prepartum pasture and managed similarly until the time of harvest. BCS at calving was greater (P < 0.01) for LATE42 and LATE84 vs. CON cows but did not differ (P = 0.16) between LATE42 and LATE84 cows. Calving date, calving percentage, and birth BW of the first offspring did not differ (P ≥ 0.22) among treatments. However, LATE42 cows calved their second offspring 8 d earlier (P = 0.04) compared with CON and LATE84 cows. At weaning (first offspring), LATE84 calves were the heaviest (P ≤ 0.05), CON calves were the lightest, and LATE42 calves had intermediate BW (P ≤ 0.05). Steer plasma concentrations of cortisol and haptoglobin and serum bovine viral diarrhea virus type-1 titers did not differ (P ≥ 0.21) between treatments. Steer serum parainfluenza-3 titers were greater (P = 0.03) for LATE42 vs. CON steers, tended to be greater (P = 0.10) for LATE84 compared with CON steers, and did not differ (P = 0.38) between LATE42 and LATE84 steers. Steer feedlot BW, average daily gain, dry matter intake, and hot carcass weight did not differ (P ≥ 0.36) between treatments. Marbling and the percentage of steers grading choice were greater (P ≤ 0.04) for LATE42 vs. CON steers, whereas LATE84 steers were intermediate. In summary, different timing of DDG supplementation during the third trimester of gestation could be explored to optimize cow BCS and offspring preweaning growth and carcass quality.

Maternal methionine supplementation during gestation alters alternative splicing and DNA methylation in bovine skeletal muscle

Background

The evaluation of alternative splicing, including differential isoform expression and differential exon usage, can provide some insights on the transcriptional changes that occur in response to environmental perturbations. Maternal nutrition is considered a major intrauterine regulator of fetal developmental programming. The objective of this study was to assess potential changes in splicing events in the longissimus dorsi muscle of beef calves gestated under control or methionine-rich diets. RNA sequencing and whole-genome bisulfite sequencing were used to evaluate muscle transcriptome and methylome, respectively.

Results

Alternative splicing patterns were significantly altered by maternal methionine supplementation. Most of the altered genes were directly implicated in muscle development, muscle physiology, ATP activities, RNA splicing and DNA methylation, among other functions. Interestingly, there was a significant association between DNA methylation and differential exon usage. Indeed, among the set of genes that showed differential exon usage, significant differences in methylation level were detected between significant and non-significant exons, and between contiguous and non-contiguous introns to significant exons.

Conclusions

Overall, our findings provide evidence that a prenatal diet rich in methyl donors can significantly alter the offspring transcriptome, including changes in isoform expression and exon usage, and some of these changes are mediated by changes in DNA methylation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08065-4.

Improving Beef Progeny Performance Through Developmental Programming

Maternal nutritional management during gestation appears to modulate fetal development and imprint offspring postnatal health and performance, via altered organ and tissue development and tissue-specific epigenetics. This review highlighted the studies demonstrating how developmental programming could be explored by beef producers to enhance offspring performance (growth, immune function, and reproduction), including altering cow body condition score (BCS) during pregnancy and maternal supplementation of protein and energy, polyunsaturated fatty acids (PUFA), trace minerals, frequency of supplementation, specific amino acids, and vitamins. However, this review also highlighted that programming effects on offspring performance reported in the literature were highly variable and depended on level, duration, timing, and type of nutrient restriction during gestation. It is suggested that maternal BCS gain during gestation, rather than BCS per se, enhances offspring preweaning growth. Opportunities for boosting offspring productive responses through maternal supplementation of protein and energy were identified more consistently for pre- vs. post-weaning phases. Maternal supplementation of specific nutrients (i.e., PUFA, trace minerals, and methionine) demonstrated potential for improving offspring performance, health and carcass characteristics during immunological challenging scenarios. Despite the growing body of evidence in recent years, the complexity of investigating developmental programming in beef cattle production is also growing and potential reasons for current research challenges are highlighted herein. These challenges include: (1) intrinsic difficulty of accurately measuring cow milk production multiple times in cow-calf systems; (2) larger focus on Bos taurus vs. Bos indicus breeds despite the predominance of Bos indicus-influenced beef breeds in tropical/subtropical environments and their specific, and sometimes opposite, physiological and performance outcomes compared to Bos taurus breeds; (3) limited focus on interaction between prenatal and postnatal management; (4) sex-specific outcomes following similar maternal nutrition during gestation; (5) greater focus on nutrient deficiency vs. excess; (6) limited implementation of immunological challenges; and (7) lack of multigeneration and longer periods of offspring evaluation. This review provides multiple evidence that such obstacles need to be overcome in order to significantly advance the scientific knowledge of developmental programming in beef cattle and promote global beef production.

Impacts of Nutritional Management During Early Postnatal Life on Long-Term Physiological and Productive Responses of Beef Cattle

Effective early postnatal nutritional management is a crucial component of livestock production systems, and nutrient manipulation during this period has been shown to exert long-term consequences on beef cattle growth and physiology. Metabolic imprinting defines these biological responses to a nutritional intervention early in life that permanently alter physiological outcomes later in life. Early weaning has been used to study metabolic imprinting effects, given that it allows for nutritional manipulation of animals at a young age. This practice has been shown to enhance carcass characteristics in feedlot cattle and accelerate reproductive development of females. Another strategy to study the effects of metabolic imprinting without the need for early weaning is to provide supplements via creep feeding. Providing creep feed to nursing cattle has resulted in transient and long-term alterations in cattle metabolism, contributing to increased reproductive performance of developing heifers and enhanced carcass quality of feeder cattle. Collectively, results described herein demonstrate nutrient manipulation during early postnatal life exerts long-term consequences on beef cattle productivity and may be a strategy to optimize production efficiency in beef cattle systems.

Prenatal immune stimulation alters the postnatal acute phase and metabolic responses to an endotoxin challenge in weaned beef heifers. Transl Anim Sci 2021;5:txab097. [PMID: 34250451 DOI: 10.1093/tas/txab097]

This study evaluated whether administration of lipopolysaccharide (LPS) at each trimester of gestation would alter the acute phase (APR) and metabolic responses to a postnatal LPS challenge in weaned heifers. Pregnant crossbred multiparous cows (n = 50) were randomized into prenatal immune stimulation (PIS; n = 24; administered 0.1 µg/kg BW LPS subcutaneously at 71 ± 2, 170 ± 2 and 234 ± 2 d of gestation) and saline (CON; n = 26) groups. From these treatment groups, heifer calves (n = 12 PIS and 11 CON) were identified at weaning (244 ± 3 d of age) to receive an LPS challenge. On d 0, heifers were fitted with vaginal temperature (VT) devices, jugular catheters, and moved into individual stalls. On d 1, heifers were challenged i.v. with LPS (0.5 µg/kg BW) at 0 h. Blood samples were collected and sickness behavior scores (SBS) recorded at 0.5 h intervals from -2 to 8 h and at 24 h relative to LPS challenge. Serum was analyzed for cortisol, cytokines, glucose, non-esterified fatty acids (NEFA), and serum urea nitrogen (SUN) concentrations. Baseline VT was lesser in PIS heifers from -11 to -5 h pre-LPS (treatment × time: P < 0.01) compared to the CON; however, the post-LPS VT response did not differ between treatments (P = 0.89). There was a treatment × time interaction (P < 0.01) for SBS with PIS heifers having lesser SBS from 0.5 to 2 h post-LPS compared to CON. There was a treatment × time interaction (P = 0.03) for cortisol with PIS heifers having greater cortisol at 0.5, 3, 3.5, 5.5 and 6.5 h post-LPS compared to CON. There were treatment × time interactions for the post-LPS cytokine responses (P ≤ 0.05). Specifically, PIS heifers had greater TNF-α from 1.5 to 2 h, yet less TNF-α at 3 h than CON (P < 0.01), and PIS heifers had greater IFN-γ from 3.5 to 5.5 h post-LPS than CON (P < 0.01). In contrast, IL-6 was less in PIS than CON heifers from 1.5 to 8 h post-LPS (P < 0.001). Glucose concentrations were greater in PIS heifers at -1 h, but less at 2, 3 and 5.5 h compared to CON (treatment × time: P < 0.01). Serum NEFA concentrations were greater (P = 0.04) in PIS than CON heifers. There was a treatment × time interaction (P < 0.01) for SUN with PIS heifers having greater SUN concentrations at -2, -1.5, 2, 3, 6.5 and 24 h than CON. These data demonstrate that in utero exposure to multiple low doses of endotoxin has lasting physiological and immunological effects when the offspring encounter a similar postnatal immunological insult.

Use of radio-frequency identification technology to assess the frequency of cattle visits to mineral feeders

Three experiments were conducted to evaluate the frequency of visits to a mineral feeder equipped with radio-frequency identification (RFID). In Exp. 1, twelve heifers (Braford, Brahman, and White Angus; n = 4/breed) were fitted with RFID ear tags and placed into a pasture with access to a RFID-equipped mineral feeder. Number of visits were greater (P ≤ 0.05) during daytime than the night period. Brahman and Braford heifers favored (P ≤ 0.05) daytime than night period. White Angus heifers did not display a specific period preference (P = 0.32). In Exp. 2, Black Angus and Brahman cows (n = 15 and 19, respectively) were placed into a pasture with access to a RFID-equipped mineral feeder. Brahman cows made more (P < 0.01) visits to the mineral feeder than Black Angus cows. There were no breed differences on the number of visits during the morning (P = 0.25) and night (P ≤ 0.25) periods, but Brahman cows made more (P ≤ 0.05) visits to the mineral feeder in the afternoon period than Black Angus cows. In Exp. 3, the location of the mineral feeder was tested using 3 groups of Bos indicus-influenced heifers (n = 12/group). The mineral feeder was moved weekly within pasture. The number of visits to the mineral feeder differed for each location (P < 0.001) with visits being greatest when mineral feeder was placed near supplement and water, followed by center of the pasture, and lastly in the shade.

Effects of Winter vs. Year-round Supplementation of Multiparous Bos Indicus-influenced Beef Cows on Offspring Postnatal Growth, Immunity, and Carcass Characteristics

This 2-yr study evaluated the effects of winter vs. year-round supplementation of Bos indicus-influenced beef cows on offspring feedlot performance. Brangus cows (82–84 cows/yr) were stratified by BW and BCS (475 ± 67 kg; 4.85 ± 0.73) and randomly assigned to bahiagrass pastures (13–14 cows/pasture). Treatments were randomly assigned to pastures (2 pastures/treatment/yr) and consisted of winter supplementation with molasses (MOL-W), or year-round supplementation with molasses (MOL-Y) or cubes (CUB-Y). Supplements were isocaloric and isonitrogenous (75% TDN, 20% CP; DM basis). Total yearly supplement DM amount was 272 kg/cow for all treatments. At weaning (d 421), 33–35 steers/yr were vaccinated against bovine respiratory disease, transported for 720 miles to the feedlot, penned according to prepartum pasture distribution, and fed the same corn silage-based diet until harvest. Data were analyzed using SAS GLIMMIX procedure. Cow BCS at calving was greater (P &lt; 0.01) for MOL-Y and CUB-Y vs. CON cows. Calving rate, calving date, calf birth weight, and calf preweaning BW did not differ (P ≥ 0.22) among treatments. Steer feedlot BW did not differ (P ≥ 0.36) at time of feedlot entry but was greater (P ≤ 0.05) for MOL-Y and MOL-W steers vs. CUB-Y steers at feedlot exit. Plasma haptoglobin concentrations at feedlot entry were greater (P = 0.05) for CUB-Y vs. CON steers, with MOL-Y steers being intermediate, whereas plasma cortisol concentrations at feedlot entry were greater (P ≤ 0.05) for CUB-Y vs. MOL-Y and MOL-W steers. Marbling score, yield grade, and carcass weight did not differ (P ≥ 0.14), but CON steers had greater fat thickness at the 12th rib than MOL-Y and CUB-Y steers. Hence, year-round supplementation (molasses or cubes) of beef cows increased cow BCS at calving but had minor effects on offspring post-weaning growth and immunity compared to winter supplementation of molasses.

Timing of Protein/energy Supplementation in Late Gestating Bos Indicus-influenced Beef Cows Influences Postnatal Growth, Immunity and Carcass Characteristics of Their Offspring

This 2-yr study investigated the timing of dried distillers grains (DDG) supplementation of Bos indicus-influenced cows during late gestation and its impacts on offspring performance. On d 0, 84 Brangus cows/yr were stratified by BW (482 ± 75 kg) and BCS (5.3 ± 0.8) and randomly assigned to bahiagrass pastures (14 cows/pasture). Treatments were randomly assigned to pastures (2 pastures/treatment/yr) and consisted of no prepartum supplementation (CON), 2 kg/d of DDG from d 0 to 42 (LATE42), or 1 kg/d of DDG from d 0 to 84 (LATE84). At weaning (d 347), 38 steers/yr were vaccinated against bovine respiratory disease, transported for 720 mi to the feedlot, penned according to prepartum pasture distribution, and fed the same corn silage-based diet until harvest. Data were analyzed using SAS GLIMMIX procedure. Cow BCS at calving was greater (P ≤ 0.05) for LATE84 and LATE42 vs. CON cows and did not differ (P = 0.16) between LATE84 and LATE 42 cows. Cows offered LATE42 supplementation had greater (P ≤ 0.05) calving percentage from wk 2 to 6 of the subsequent calving season than CON and LATE84 cows. Calf BW at weaning was greater (P ≤ 0.05) for LATE 84 vs. LATE42 calves, and the latter greater than CON calves (269, 261, and 255 ± 2.6 kg, respectively). Seroconversion against parainfluenza-3 virus at weaning was greater (P ≤ 0.05) for LATE42 vs. CON steers, with LATE84 being intermediate. Feedlot BW and carcass weight did not differ (P ≥ 0.36) among treatments, but marbling scores and carcasses grading choice tended (P ≤ 0.10) to be greater for LATE42 vs. CON steers, with LATE84 being intermediate. Therefore, timing of DDG supplementation during late gestation in Bos indicus-influenced cows enhanced calf weaning weight, humoral immunity, and carcass characteristics at different magnitudes than cohorts born from non-supplemented cows.

Differences in copper and selenium metabolism between Angus (Bos taurus) and Brahman (Bos indicus) cattle

A 2-yr study was conducted at the Range Cattle Research and Education Center, University of Florida - Institute of Food and Agricultural Sciences (IFAS) (Ona, FL), to evaluate differences in the metabolism of Cu and Se of Angus (Bos taurus) and Brahman (Bos indicus) cattle. Thirty-two pregnant beef cows (n = 8 Brahman and 8 Angus/yr) were enrolled in the study in the first trimester of gestation. This study consisted of three phases: 1) restriction (day 0 to 90), 2) supplementation (day 91 to 150), and 3) calving. During all three phases, cows were individually fed and housed in partially covered drylot pens. During the restriction and supplementation phases, cows were provided a 1.5 kg/d of a grain-based concentrate supplement, which was fortified with flowers of S (50 g of supplemental S/cow daily; restriction phase) or Cu and Se (100 and 3 mg/d of Cu and Se, respectively; supplementation phase). Blood and liver samples were collected from all cows at 30 d intervals and from both cows and calves within 24 h of calving. Colostrum and milk samples were collected at calving and 7 d after birth. All data were analyzed using the MIXED procedure of SAS, where cow and calf were the experimental unit. During the restriction phase, a breed × day effect (P = 0.03) was observed where Brahman had greater liver Cu concentration than Angus cows in all sampling days. For liver Se concentration, a tendency (P = 0.07) for a breed effect was observed where Angus cows tended to have greater liver Se concentration than Brahman. During the supplementation phase, breed (P < 0.001) and day (P < 0.01) effects were observed, where Brahman cows had greater liver Cu concentration than Angus. For liver Se concentration, a day effect (P < 0.001) was observed, where liver Se concentration increased (P < 0.001) from day 90 to 120 and remained unchanged (P = 0.86) until day 150. At calving, no effects of breed (P = 0.34) were observed for liver Cu concentration of cows; however, Brahman calves tended (P = 0.09) to have greater liver Cu concentration than Angus calves. For Se liver concentration at calving, Angus cows tended (P = 0.07) to have greater liver Se concentration than Brahman cows; however, no breed differences (P = 0.70) were observed for liver Se concentration of calves at birth. In summary, substantial differences in multiple indicators of Cu and Se status were observed between Angus and Brahman cattle, implying that Angus and Brahman cattle possibly have different mechanisms to maintain adequate Cu and Se status.

Supplementation frequency and amount modulate postweaning growth and reproductive performance of Bos indicus-influenced beef heifers

This 2-yr study evaluated the growth and puberty attainment of Bos indicus-influenced beef heifers offered 2 different postweaning concentrate supplementation amounts and delivery frequencies. On day 0 of each year, 64 Brangus crossbred heifers were stratified by initial body weight (BW) and age (mean = 244 ± 22 kg; 314 ± 17 d) and assigned into 1 of 16 bahiagrass pastures (4 heifers/pasture/yr). Treatments were randomly assigned to pastures in a 2 × 2 factorial design (4 pastures/treatment/yr) and consisted of concentrate dry matter (DM) supplementation at 1.25% or 1.75% of BW which were offered either daily (7×) or 3 times weekly (3×) for 168 d. On day 56 of each year, heifers were assigned to an estrus synchronization protocol consisting of intravaginal controlled internal drug release (CIDR) insertion on day 56, CIDR removal on day 70, i.m. injection of 25 mg of prostaglandin F2α (PGF2α) on day 86, and i.m. injection of 100 µg of gonadotropin-releasing hormone and timed-AI at 66 h after PGF2α injection (day 89). Heifers were exposed to Angus bulls from day 89 to 168 (1 bull/pasture). Pregnancy diagnosis was assessed on day 213 of each year. Supplementation amount × frequency effects were not detected (P ≥ 0.12) for any variable, except for plasma concentrations of glucose (P = 0.10) and urea nitrogen (PUN; P = 0.01). Herbage mass, herbage allowance, and nutritive value did not differ (P ≥ 0.12) among treatments. Increasing supplementation DM amount from 1.25% to 1.75% of BW increased (P ≤ 0.05) plasma concentrations of insulin-like growth factor 1 (IGF-1), overall average daily gain (ADG), final BW, percentage of pubertal heifers on day 89, pregnancy and calving percentages, and percentage of heifers calving within the first 21 d of the calving season. However, reducing the supplementation frequency from daily to 3× weekly, regardless of supplementation amount, did not impact overall pregnancy and calving percentages (P ≥ 0.42), but caused (P ≤ 0.05) fluctuations in plasma concentrations of insulin and IGF-1 and decreased (P ≤ 0.03) overall ADG, final BW, puberty attainment on days 56, 89, and 168, and percentage of heifers calving during the first 21 d of the calving season. Hence, increasing the supplement DM amount did not prevent the negative effects of reducing the frequency of supplementation (3× vs. 7× weekly) on growth and reproduction of replacement Bos indicus-influenced beef heifers.

Effect of rumen-protected methionine supplementation to beef cows during the periconception period on performance of cows, calves, and subsequent offspring

Maternal nutrition affects the development of the fetus and postnatal performance of the calf. Methionine may play a critical role in developmental programming and is likely deficient in beef cows fed low-quality forage. The objective of this study was to determine the effect of metabolizable methionine supply to lactating beef cows during the periconception period on performance of cows, calves, and subsequent offspring. This project involved two consecutive production cycles commencing at calving in which dietary treatments were fed to cows during the periconception period along with measurements on cows and initial calves in Production Cycle 1, and measurements on subsequent calves in Production Cycle 2. Brangus-Angus crossbred lactating beef cows (N = 108; age = 6.4 (2.8) year) were stratified by previous calving date and assigned to one of three supplements: (1) control, molasses plus urea at 2.72 kg/day as fed, (2) fishmeal, 2.27 kg/day molasses plus urea plus 0.33 kg/day as fed of fishmeal, and (3) methionine, 2.72 kg/day of molasses plus urea plus 9.5 g/day of 2-hydroxy-4-(methylthio)-butanoic acid. Cows were fed supplements and low-quality limpograss (Hemarthria altissima) hay while grazing dormant bahiagrass (Paspalum notatum Flüggé) pastures during the 115-day periconception period from December 2014 to April 2015 in Production Cycle 1 only. Body weight change and milk yield of cows were measured during the periconception period in Production Cycle 1. Body weight of calves was measured at birth and weaning in both production cycles. Following weaning in Production Cycle 2, eight subsequent steer calves per treatment were individually housed for a 42-day metabolism experiment. Treatment did not affect (P > 0.10) BW change of cows, but cows fed methionine tended (P = 0.09) to produce more energy-corrected milk than control and fishmeal. Treatment did not affect (P > 0.10) 205-day adjusted weaning weight of calves in either production cycle. During the metabolism experiment, subsequent calves from dams fed fishmeal and methionine gained faster (P < 0.05) and had greater (P < 0.05) gain:feed than control calves. Methionine calves tended (P = 0.06) to have greater apparent total tract NDF and ADF digestibility and lesser (P < 0.05) blood glucose concentration than control and fishmeal calves. These data indicate that maternal methionine supply during the periconception period plays an important role in programming future performance of the offspring.

PSIV-10 Effects of stair-step vs. constant supplementation amount on growth, reproduction, and intravaginal temperature in Bos indicus-influenced beef heifers

This study investigated growth and reproductive performance of Bos indicus-influenced beef heifers provided a concentrate supplement at either a constant or stair-step supplementation. Sixty-four Brangus heifers were stratified by initial BW and age (255 ± 20 kg; 270 ± 22 d) and assigned to 1 of 16 bahiagrass pastures (4 heifers/pasture). Treatments were randomly assigned to pastures (8 pastures/treatment) and consisted of concentrate DM supplementation at: (1) 1.50% of BW from d 0 to 100 (CON) and (2) 1.05% of BW from d 0 to 49 and 1.95% of BW from d 50 to 100 (STP). Supplementation started on d 0 and continued until start of estrous synchronization on d 100. Intravaginal temperatures (16 heifers/treatment) were collected every 30 minutes from d 25 to 31 (September) and d 85 to 91 (November). All heifers were provided supplement at 1.50% of BW from d 101 to 211. Heifers were bred by AI from d 113 to 115 and Brangus bulls were placed with heifers from d 121 to 211. Data were analyzed using the MIXED procedure of SAS with treatment, time, and interaction as fixed effects. From d 0 to 49, ADG did not differ (P = 0.87); however, STP heifers had greater (P = 0.01; 0.73 vs. 0.56 kg/d) ADG from d 50 to 100 compared to CON heifers. Percentage of pubertal heifers, percentage of heifers in estrus, or reproductive tract scores did not differ between treatments (P ≥ 0.40). Intravaginal temperatures were greater (P &lt; 0.0001) for CON vs. STP heifers from d 25 to 31 but did not differ (P = 0.74) from d 85 to 91. Using a stair-step vs. constant supplementation amount (1.05 to 1.95% vs. 1.50% of BW) before the breeding season reduced intravaginal temperatures and increased overall ADG in Bos indicus-influenced beef heifers.

PSII-8 Different nutritional management strategies post-weaning in growth and reproductive performance of Nellore heifers

The objective of this study was to evaluate different nutritional management strategies (drylot vs. supplementation on pasture) to optimize growth and reproductive performance of Nellore heifers submitted to the fixed-time artificial insemination (FTAI) at 14–15 mo. On d0, 126 weaned Nellore heifers (152±22 kg of BW; 240±28 days of age) were stratified by BW and age, and randomly assigned to receive: (1) high-concentrate-based diet (62.2% TDN, 12.0% CP of DM of diet) ad libitum in feedlot from d 0 to 246 (FDL; 6 pens and 7 heifers/pen); (2) fixed supplementation at 1% of BW on Brachiaria pastures from d0 to 246 (PAS10; 6 pastures; 7 heifers/pastures and 4 ha/pasture); and (3) increasing supplementation on Brachiaria pastures at 0.8% of BW from d 0 to 80 and 1.2% of BW from d 81 to 246 (PAS812; 6 pastures; 7 heifers/pastures and 4 ha/pasture). Supplement offered to heifers on pasture consisted of corn, soybean meal, urea, and minerals (78% TDN, 22% CP of DM at dry season and 79% TDN, 20% CP of DM at rainy season). Final pregnancy rate was determined on d238. Heifer BW on d160 was greater (P &lt; 0.01) for FDL vs. PAS10 and PAS812 (264 vs. 251 and 253±10.1 kg, respectively). Overall ADG from d0 to the start of breeding season (d160) and BW on d246 were greater (P &lt; 0.01) for FDL vs. PAS10 and PAS812 (0.72 vs. 0.62 and 0.64±0.02 kg/d, and 325 vs. 310 and 316 ±10.3 kg, respectively). Heifer BW on d160 and 246 and ADG from d0 to 160 did not differ between PAS10 and PAS812 (P ≥ 0.33). Final pregnancy rates did not differ (P = 0.75) among treatments. Therefore, growth performance, but not pregnancy rates following FTAI, was enhanced for Nellore heifers developed in drylot vs. pasture systems and submitted to FTAI at 14–15 mo.

PSVII-8 miRNAs explain the variation in muscle and blood transcriptomes of beef calves born from dams with or without energy restriction during late gestation

Maternal energy restriction during late gestation affects the expression of genes related to energy metabolism in muscle and immune response in blood. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression post-transcriptionally. The aim of this study was to identify potentials miRNA involved in the expression of differentially expressed genes (DEG) in muscle and blood following exposure to maternal gestational energy restriction. Forty days before the expected calving date, cows were assigned to one of two diets: 100% (CTRL) or 70% (REST) of the daily energy requirement. For RNA-seq analysis, muscle samples were collected from 12 heifers and 12 steers, and blood samples were collected from 12 steers. miRNAs were identified from the RNA-seq data based on the bovine genome annotation, with 38 and 10 miRNAs identified in blood and muscle, respectively. The expression of the miRNAs and the previously identified 160 and 450 DEGs in muscle and blood, respectively, was pre-adjusted for fixed effects before final analyses. A stepwise selection (P-value &lt; 0.05) was used to identify miRNAs (dependent variables) explaining variation in DEGs, for each DEG at a time, and analyses performed separately for blood and muscle. The R2 of selected models ranged from 0.88 to 0.99 in muscle and 0.92 to 0.99 in blood. Of the most selected miRNA in muscle, MiR-133a and MiR-1 are known to be related to muscle hypertrophy, and MiR-143 and bta-let-7i promote adipocyte differentiation. Of the most selected miRNA in blood, MiR-21 regulates immune system by different pathways. Using RNA-seq data, we identified miRNAs explaining a large amount of the variation of DEGs, with the identification of important miRNAs related to muscle development and immune system.

190 Winter vs. year-round supplementation of mature beef cows on feedlot performance and carcass characteristics of steer progeny

This study evaluated the effects of year-round supplementation of molasses/urea or wheat middlings-based range cubes to mature cows on subsequent feedlot growth, immunity, and carcass characteristics of their steer progeny. On d 0, 82 mature Brangus cows were stratified by BW and BCS (433 ± 47 kg; 4.6 ± 0.77) and randomly allocated into 1 of 6 bahiagrass pastures (13–14 cows/pasture). Treatments were randomly assigned to 2 pastures/treatment and consisted of supplementation with molasses/urea during winter (MOL-W), or year-round supplementation with molasses/urea (MOL-Y) or range cubes (CUB-Y). Supplements were isocaloric and isonitrogenous (75% TDN, 20% CP; DM basis) and offered at a total yearly supplement DM amount of 272 kg/cow. On d 423, all calves were weaned, and 33 steers were randomly selected for the feedlot phase. Steers were penned based on cow prepartum pasture distribution and managed similarly until slaughter (d 661). Data were analyzed as complete randomized design using MIXED procedure of SAS, pasture as the experimental unit, treatment as fixed effect, and pasture(treatment) and steer(pasture) as random effects. Dry matter intake did not differ (P ≥ 0.70), but MOL-Y and MOL-W steers had greater (P = 0.05) overall ADG vs. CUB-Y steers. Plasma haptoglobin concentrations tended (P = 0.06) to be greater for CUB-Y vs. MOL-W, and intermediate for MOL-Y. Serum titers against bovine viral diarrhea virus-1 and parainfluenza-3, hot carcass weight, REA, and YG did not differ (P ≥ 0.16) among treatments, but back fat thickness was greater (P = 0.03) for MOL-W vs. MOL-Y and CUB-Y. The percentage of carcasses grading Choice did not differ (P = 0.35) among treatments, but more carcasses tended (P = 0.08) to grade low Choice for MOL-W vs. CUB-Y and MOL-Y. Therefore, providing molasses/urea supplementation to mature beef cows during winter only or year-round increased steer post-weaning feedlot performance and carcass quality compared to steers born from cows offered year-round supplementation with range cubes.

55 Effects of concentrate supplementation frequency and amount on growth and reproductive performance of Brangus heifers

A 2-yr study evaluated the impacts of supplementation frequency and amount on growth and puberty attainment of Brangus heifers. On d 0 of each year, 64 Brangus heifers were stratified by BW and age (244 ± 4 kg; 311 ± 18 d) and assigned to 1 of 16 bahiagrass pastures (4 heifers/pasture). Treatments were randomly assigned to pasture (4 pastures/treatment) in a 2 × 2 factorial design and consisted of heifers offered a soybean hulls-based supplement DM at 1.25% or 1.75% of BW delivered either daily (7X) or 3 times weekly (3X; Monday, Wednesday, and Friday). On d 56, heifers were inserted with a CIDR device for 14 d, followed by administration of PGF2α and a timed-AI+GnRH protocol on d 89. Heifers were exposed to bulls from d 89 to 167. Data were analyzed using the SAS GLIMMIX procedure. No rate × frequency interactions were detected (P ≥ 0.20). Overall ADG was greater for 7X vs. 3X heifers (P = 0.007). Daily supplementation increased (P ≤ 0.03) the percentage of pubertal heifers prior to CIDR insertion and at AI compared to 3X supplementation; however, percentage of pregnant heifers did not differ (P = 0.70). Supplementation at 1.25% vs. 1.75% enhanced the overall ADG (P = 0.02) but did not impact (P = 0.18) the percentage of pubertal heifers before CIDR insertion. After the puberty induction protocol, heifers supplemented at 1.75% of BW achieved greater puberty attainment at time of AI (P = 0.05) and final pregnancy rates (P = 0.02) than heifers supplemented at 1.25% of BW. When a puberty induction protocol was included, the percentage of pregnant Brangus heifers were not affected by supplementation frequency (daily vs. 3 times weekly) but enhanced when the supplement dry matter amount was offered at 1.75 vs. 1.25% of body weight.

126 Pre- and post-partum supplementation of molasses/urea, with or without methionine fortification, to enhance growth and physiology of Bos indicus-influenced primiparous cows and their offspring

A 2-yr study evaluated the effects of molasses/urea supplementation during pre- and early postpartum, with or without methionine fortification, on growth and physiology of primiparous cows and their offspring. On d 0 of each yr, 36 cows were stratified by BW and BCS (396 ± 54 kg; 5.67 ± 0.66) and randomly assigned to 1 of 12 bahiagrass pastures (3 cows and 1.2 ha/pasture). Treatments were randomly assigned to pastures (4 pastures/treatment) and consisted of no supplementation (NOSUP), 1 kg/d of molasses/urea (MOL; DM basis), or 1 kg/d of MOL + 18 g/d of methionine hydroxy analog (MOLMET; Alimet, Novus, St. Charles, MO). Supplementation began 56 d before parturition (d 0) and ended when all cows within each pasture had calved (d 74). Calves were early weaned on d 147. On d 154, 24 calves (8 calves/treatment) were transferred to individual drylot pens, and offered ad libitum stargrass hay plus soybean hulls-based concentrate DM (75% TDN; 22% CP) at 3% of BW for 47 d. On d 160, calves were vaccinated against bovine viral diarrhea virus-1 (BVDV-1) and parainfluenza-3 (PI-3). Data were analyzed using the MIXED procedures of SAS. Cow BCS at calving was greater (P ≤ 0.05) for MOL and MOLMET vs. NOSUP but the overall percentage of pregnant cows did not differ among treatments (P = 0.82). Calf ADG from birth to drylot exit did not differ (P = 0.83) between MOL and MOLMET but was least (P ≤ 0.04) for NOSUPP calves. Seroconversion to BVDV-1 and PI-3 viruses were greater (P ≤ 0.05) for MOL and MOLMET vs. NOSUP calves. Hence, cow supplementation of molasses/urea during pre- and early postpartum improved cow prepartum BCS, and calf growth and humoral immunity. Methionine fortification of supplements did not impact cow and calf performance.

71 Effects of timing of supplementation during late gestation in Bos indicus-influenced beef cows on post-weaning growth, immunity, and carcass characteristics of steer progeny

This study evaluated the growth, immunity, and carcass characteristics of beef steers born to cows offered dried distillers grains (DDG) at different timing during late gestation. Approximately 84 d before calving (d 0), 84 mature Brangus cows were stratified by BW and BCS (422 ± 42 kg; 5.0 ± 0.14) and allocated into 1 of 6 bahiagrass pastures (14 cows/pasture). Treatments were randomly assigned to pastures: 1) no prepartum supplementation (CON); 2) 1 kg/d DDG from d 0 to 84 (LATE84); or 3) 2 kg/d from d 0 to 42 (LATE42). Calves were weaned at 261 ± 23 d of age. At weaning, 38 steers were vaccinated against bovine viral diarrhea virus (BVDV-1) and parainfluenza-3 (PI-3) and transported to a feedlot facility. Steers were penned according to cow prepartum pasture distribution and fed a similar diet until slaughter (d 587). Data were analyzed as complete randomized design using MIXED procedure of SAS, pasture as the experimental unit, treatment as fixed effect, and pasture(treatment) and steer(pasture) as random effects. Steer feedlot BW, ADG, DMI, and G:F did not differ (P ≥ 0.12) among treatments. Plasma haptoglobin concentrations were greater (P ≤ 0.03) for LATE42 and LATE84 vs. CON steers 2 d after feedlot entry. Plasma cortisol and seroconversion for BVDV-1 and PI-3 did not differ (P ≥ 0.15) among treatments. The percentage of carcasses grading Choice did not differ (P = 0.13), but carcasses grading low Choice were greater (P = 0.03) for CON vs. LATE42, with LATE84 being intermediate (91, 40, and 58%, respectively). Thus, prepartum dried distillers grain supplementation to B. indicus-influenced cows did not enhance feedlot growth but had subtle positive impacts on carcass quality and innate immunity in steer progeny. In addition, timing of dried distillers grain supplementation (last 84 d vs. first 42 d of late gestation) did not impact steer post-weaning feedlot performance and carcass quality.

Maternal supplementation of energy and protein, but not methionine hydroxy analog, enhanced postnatal growth and response to vaccination in Bos indicus-influenced beef offspring

A 2-yr study evaluated the growth and postvaccination immune response of beef calves born from heifers offered no supplementation or pre- and postpartum supplementation of sugarcane molasses + urea with or without methionine hydroxy analog (MHA). On day 0 of each year (57 ± 5 d prepartum), Brangus crossbred beef heifers (n = 36/yr; 20 to 22 mo of age) were stratified by their initial body weight (BW; 396 ± 24.1 kg) and body condition score (BCS; 5.6 ± 0.43) and randomly allocated into 1 of 12 bahiagrass (Paspalum notatum) pastures (3 heifers/pasture). Treatments were randomly assigned to pastures (4 pastures/treatment/yr) and consisted of no supplementation (NOSUP) and supplementation of sugarcane molasses + urea (7.2 kg of DM/heifer/wk) with (MOL+) or without (MOL-) fortification with 105 g/heifer/wk of MHA. Treatments were provided from 57 ± 5 d prepartum until 17 ± 5 d postpartum (day 0 to 74). On day 74, all heifer-calf pairs were combined and managed as a single group until the end of the breeding season (day 237). Calves were early weaned at 89 ± 5 d of age (day 147), limit-fed at 3.5% of BW (DM basis) in drylot until day 201, and vaccinated against respiratory disease pathogens on days 160 and 188. Prepartum BCS on day 44 did not differ (P = 0.26) between MOL+ and MOL- heifers but both groups had greater (P < 0.0001) BCS than NOSUP heifers. Plasma concentrations of l-methionine on day 44 were the greatest (P ≤ 0.04) for MOL+ heifers and did not differ (P = 0.40) between NOSUP vs. MOL- heifers. Calf birth BW did not differ (P = 0.13) among treatments. Calf average daily gain (ADG) from birth to day 201 did not differ (P ≥ 0.17) between MOL+ vs. MOL- calves, but both groups had greater (P ≤ 0.05) ADG from birth to day 201 than NOSUP calves. Calf postvaccination plasma concentrations of glucose, cortisol, and haptoglobin did not differ among treatments (P ≥ 0.13). However, plasma concentrations of IGF-1 on day 167 and the overall positive vaccine seroconversion did not differ (P ≥ 0.18) between MOL- and MOL+ calves, but both were greater (P ≤ 0.04) compared with NOSUP calves. Hence, maternal supplementation of sugarcane molasses + urea increased BCS at calving and offspring BW gain and response to vaccination against respiratory pathogens compared with no maternal supplementation. MHA inclusion into maternal supplements effectively increased maternal plasma l-methionine concentrations but did not enhance maternal BCS at calving and offspring growth and postvaccination immune response.

Differential network analysis of bovine muscle reveals changes in gene coexpression patterns in response to changes in maternal nutrition

Background

Coexpression network analysis is a powerful tool to reveal transcriptional regulatory mechanisms, identify transcription factors, and discover gene functions. It can also be used to investigate changes in coexpression patterns in response to environmental insults or changes in experimental conditions. Maternal nutrition is considered a major intrauterine regulator of fetal developmental programming. The objective of this study was to investigate structural changes in gene coexpression networks in the muscle of bull beef calves gestated under diets with or without methionine supplementation. Both muscle transcriptome and methylome were evaluated using next generation sequencing.

Results

Maternal methionine supplementation significantly perturbed coexpression patterns in the offspring’s muscle. Indeed, we found that neither the connection strength nor the connectivity pattern of six modules (subnetworks) detected in the control diet were preserved in the methionine-rich diet. Functional characterization revealed that some of the unpreserved modules are implicated in myogenesis, adipogenesis, fibrogenesis, canonical Wnt/β-catenin pathway, ribosome structure, rRNA binding and processing, mitochondrial activities, ATP synthesis and NAD(P) H oxidoreductases, among other functions. The bisulfite sequencing analysis showed that nearly 2% of all evaluated cytosines were differentially methylated between maternal diets. Interestingly, there were significant differences in the levels of gene body DNA methylation between preserved and unpreserved modules.

Conclusions

Overall, our findings provide evidence that maternal nutrition can significantly alter gene coexpression patterns in the offspring, and some of these perturbations are mediated by changes in DNA methylation.

Cattle adapted to tropical and subtropical environments: social, nutritional, and carcass quality considerations

Beef production needs to increase from 60 million to 130 million tons by 2050 to feed a growing world population, and 70% of this production increase is expected from beef industries located in subtropical and tropical regions of the world. Bos indicus-influenced cattle predominate in these regions but are often managed using practices developed for Bos taurus breeds reared in temperate climates. Hence, a fundamental step to meet the increasing global demand for beef is to develop specific management for B. indicus-influenced cattle in tropical or subtropical environments. Bos taurus and B. indicus are different subspecies, and diverge in social and biological functions due to selection pressure caused by complex evolutionary and domestication processes. Bos indicus cattle display different social responses compared with B. taurus counterparts, which must be taken into account by management planning as these traits directly impact cattle performance and welfare. In tropical and subtropical regions, warm-season perennial C4 grasses are the dominant forages, and their availability has a significant influence on the productivity of beef cattle systems. The resilience of C4 grasses under adverse conditions is one of their most important characteristics, even though these forages have reduced nutritive value compared with forages from temperate climates. Accordingly, nutritional planning in tropical and subtropical conditions must include management to optimize the quantity and quality of C4 forages. Nutritional requirements of cattle raised within these conditions also require special attention, including inherent metabolic compromises to cope with environmental constraints and altered energy requirements due to body composition and heat tolerance. Nutritional interventions to enhance beef production need to be specifically tailored and validated in B. indicus-influenced cattle. As an example, supplementation programs during gestation or early life to elicit fetal programming or metabolic imprinting effects, respectively, yield discrepant outcomes between subspecies. Bos indicus-influenced cattle produce carcasses with less marbling than B. taurus cattle, despite recent genetic and management advances. This outcome is mostly related to reduced intramuscular adipocyte volume in B. indicus breeds, suggesting a lesser need for energy stored intramuscularly as a mechanism to improve thermotolerance in tropical and subtropical climates.

32 Nutritional management of forage-based cow-calf operations

The beef cattle industry in the Southeastern United States relies primarily on forages that not always meet the cowherd nutritional requirements, resulting in reduced performance if supplemental nutrients are not provided. Although precalving nutrition modulates postnatal offspring performance, most studies did not utilize Bos indicus-influenced cows consuming low-quality, warm-season forages. Hence, 3 studies evaluated the impact of different supplementation strategies during gestation on subsequent cow and calf performance.Study 1focused on timing of dried distillers grains (DDG) supplementation during late-gestation. Treatments initiated 84 d before calving and consisted of no supplementation, 1 kg/d of DDG from d 0 to 84, or 2 kg/d of DDG from d 0 to 42. Timing of prepartum DDG supplementation did not impact cow reproduction, but calf pre-weaning growth was enhanced only when cows received longer vs. shorter or no periods of prepartum supplementation. Study 2evaluated the use of prepartum supplementation of sugarcane molasses/urea added or not with DL-methionine hydroxyl analog. At 56 d before calving, Brangus heifers received no supplementation or molasses/urea (7.2 kg DM/wk) with or without methionine (105 g/wk; Alimet, Novus) until calving. Sugarcane molasses/urea supplementation improved cow BCS at calving and calf postnatal growth compared to no supplementation. However, supplemental methionine did not further enhance cow and calf growth performance. Study 3 compared winter vs. annual supplementation of sugarcane molasses/urea or range cubes. Starting on d 0 (pregnancy diagnosis; May), Brangus cows were assigned to receive molasses/urea supplementation during winter only (calving until end of breeding season) or year-round supplementation of molasses/urea or range cubes. Treatments had similar annual supplement DM amount (272 kg/yr). Year-round supplementation of molasses/urea and range cubes enhanced cow BCS at calving but did not impact pregnancy rate of cows and calf weaning weights than winter molasses/urea supplementation.

193 Evaluation of copper and selenium metabolism in Bos indicus and Bos taurus cows

A two-year study was conducted to evaluate the differences in metabolism of Cu and Se among Bos indicus and Bos taurus cows. Thirty-two pregnant cows were enrolled in the study (n = 16/ year; 8 Brahman and 8 Black Angus). Cows were randomly assigned to individual pens at the beginning of the study, which was divided in 3 phases: depletion, repletion and calving. Throughout the study cows were fed grain supplement and had access to hay. During the depletion phase grain supplement was enriched with S (50g/head daily) to promote a decline in Cu and Se status. During the repletion phase, the extra S was removed from the grain supplement and Cu (100 mg/head daily) and Se were added (3 mg/head daily). To evaluate the mineral status, liver samples were collected from cows every 30 days and from calves at birth. Initial data was evaluated using the PROC MIXED procedure of SAS. No treatment effects (P = 0.14) were observed for liver Cu concentration, excepted for a day effect (P ≤ 0.01) as expected by the study design. Although there was a treatment x year interaction (P ≤ 0.01) for liver Se concentration a tendency for treatment (P = 0.10) was observed, where Angus cows tended to have greater liver Se concentration than Brahman cows (0.81 and 0.71 mg/kg; SEM = 0.048). No differences (P = 0.71) were observed for calf liver Cu (265 and 345 mg/kg; SEM = 94; respectively for Angus and Brahman) and Se (1.13 and 1.07 mg/kg; SEM = 0.11; respectively for Angus and Brahman) concentrations at birth. Similarly, no differences (P = 0.39) were observed for cotyledon Cu (7.7 and 6.0 mg/kg; SEM = 1.02; respectively for Angus and Brahman) and Se (0.74 and 0.77 mg/kg; SEM = 0.06; respectively for Angus and Brahman) concentrations.

PSVII-11 Monensin and supplementation level effects on ruminal parameters and in-situ disappearance of steers receiving bermudagrass

The objective of this study was to evaluate the effects of monensin and supplementation level on bermudagrass (Cynodon dactylon) in situ disappearance and ruminal parameters. The experiment was conducted in Ona, FL. Treatments were the factorial arrangement of 2 supplementation levels [0.4 (low) or 4 kg/d (high)] and 2 monensin levels (20 mg/kg of the DM intake or no monensin) distributed in a latin square design. Four rumen-cannulated steers were used with 10-d adaptation and 3-d incubation and collection periods. Samples were incubated in the rumen with nylon bags and analyzed for DM, CP, and NDF disappearance. Rumen fluid was collected for 3 d during the incubation period and analyzed for pH, ammonia, propionate, lactate, and butyrate. There was no effect (P &gt; 0.05) of monensin on potential DM, CP, and NDF disappearance; however, greater supplementation level increased (P &lt; 0.03) potential DM disappearance (64 vs. 61%) and NDF disappearance (60 vs. 57%). Steers receiving greater supplementation level had greater (P = 0.01) total DMI (1.4 vs. 1.0% BW) but there was no difference in forage DMI (P = 0.72, mean = 1.0 ± 0.1% BW). There was a monensin × supplementation level interaction on ruminal propionate concentration. The interaction occurred because there was no effect (P = 0.64) of monensin with low supplementation (mean = 12 ± 1.2 mol/100 mol); however, monensin increased propionate on high supplementation from 15 to 19 mol/100 mol. There was an increase (P &lt; 0.05) in ruminal ammonia (from 1.9 to 4.4 mg/100 ml) and lactate (from 60 to 64 mol/100 mol) from low to high supplementation. Rumen pH and butyrate were not affected by monensin or supplementation (P &gt; 0.12). Monensin did not change forage disappearance parameters but increased ruminal propionate production in steers receiving greater amount of concentrate.

Effect of a trace mineral injection at weaning on growth, antioxidant enzymes activity, and immune system in Nellore calves

The objective of this study was to evaluate the effects of injectable trace minerals (ITM) at the time of weaning on growth, antioxidant, and immune response of Nellore (Bos indicus) calves. Weaned calves (n = 159; 213 ± 32 kg) were stratified by body weight (BW) and randomly assigned to 1 of 2 treatments: injection (1 mL/45 kg of BW) of saline or ITM. Saline solution consisted of 0.9% NaCl, whereas ITM had 60, 10, 5, and 15 mg/mL of Zn, Mn, Se, and Cu, respectively. The application of ITM increased (P ≤ 0.04) the plasma concentrations of superoxide dismutase on day 7 and plasma glutathione peroxidase on day 7 and day 21. The ITM calves had greater leukocyte concentration on day 64 (P = 0.04), whereas neutrophil and mast cell concentrations did not differ (P ≥ 0.67) between treatments. The ITM calves tended (P ≤ 0.08) to have greater concentrations of lymphocytes on day 64 and eosinophils on day 21, but not (P ≥ 0.15) monocytes, erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin compared to saline calves. The ITM calves had less mean corpuscular hemoglobin concentration (MCHC; P = 0.02) and tended to have increased platelet concentrations on day 21 (P = 0.08). Growth performance did not differ between treatments (P ≥ 0.78). Thus, ITM at weaning did not impact growth performance, but increased plasma concentrations of antioxidant enzymes and blood platelets, improved components of the immune system, and reduced MCHC of Nellore calves.

144 Monensin effects on beef calves receiving limited creep-feeding supplementation

Monensin is a feed additive used to increase performance of beef cattle; however, the effects on cattle grazing warm-season perennial forages with limited levels of concentrate are inconsistent. The objective of this study was to test the effects of monensin on performance of beef calves receiving limited creep-feeding supplementation. The experiment was conducted in Ona, FL, from April to August (112 d) 2018. The creep-feeding supplementation level was 400 g of soybean meal/d. Calves were supplemented 3 days per week, Monday, Wednesday, and Friday, thus the daily supplementation level was multiplied by 7 d and divided by 3 feeding days. Treatments were monensin (20 g/kg of the expected DMI) or control (no monensin), distributed in a randomized complete block design with four replicates. Twenty four cow-calf pairs (415±29 and 162±35 kg, respectively) were randomly distributed in eight limpograss (Hemarthria altissima) pastures (experimental units; 1.0 ha/pasture; 3 cow-calf pairs/pasture). Pastures were grazed with a continuous and fixed stocking rate. There was no difference in herbage mass (mean = 2,250 kg/ha, P =0.52, SE = 120) and herbage allowance (HA, mean = 1.2 kg DM/kg LW, P = 0.52, SE = 0.04) between treatments. In addition, there was no effect of monensin on calf average daily gain (mean = 0.77 kg/d, P = 0.27, SE = 0.04), cow body condition score (BCS, mean = 5.1, P = 0.15, SE = 0.15), and calf coccidia infestation (mean = 0.18 log egg count, P = 0.98, SE = 0.08). Calves receiving monensin consumed a lesser (P < 0.01) proportion of the supplement than control in the first 13 h after supplementation (76 vs. 95%). Monensin was not effective to increase performance of beef calves receiving limited creep-feeding supplementation.

61 2018 Southern Section Extension Forum: Collaborating to meet the needs of clientele

A two-day forum was held at the University of Tennessee (UT) Middle Tennessee Research and Education Center to foster collaborative efforts between Extension specialists and county or area agents across the southern United States. The forum was attended by 28 specialists and 18 county or regional agents from across the Southern Section of ASAS. The forum began with a tour of the UT Heifer Development Center. The forum was split into three sessions and included: 1. Transfer of knowledge (Demonstration research), 2. Developing formal education for Extension agents, and 3. Collaborating across state lines to develop Extension Programs. Within each section, a brief presentation was given, followed by break-out sessions to discuss success stories from each state and potential programs to implement. From the break-out session, areas of need identified primarily focused on the development of support resources for Extension agents. Needed outputs identified included a resource guide for conducting on-farm research and demonstration projects with county and regional Extension agents, defining a regional process to provide formal distance education for agents, and development of online coursework and training tools for agents for continuing education. Assessment data indicate that participants had completed an average of 8.4 (± 6.65, range 0.5 to 24) years of service. Agents were asked to rank their level of confidence, using a 5-point Likert scale, with three tasks. Averages (SEM) of that self-assessment are indicated in Table 1. The 2018 Southern Section Extension Forum was a successful effort to bring together collaborators to identify needs and propose programs to improve the impact of Extension.

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23 Timing of concentrate supplementation during late gestation impacts calf pre-weaning growth, but not reproductive performance of Bos indicus-influenced cows

This study evaluated the effects of timing of dried distillers grains (DDG) supplementation during late-gestation on performance of Bos indicus-influenced cow-calf pairs. At about 84 d before calving (d 0), 84 mature Brangus cows were stratified by BW and BCS (422 ±42 kg; BCS = 5.0 ± 0.14) and assigned randomly to bahiagrass pastures (14 cows/pasture). Treatments were assigned randomly to pastures (2 pastures/treatment) and consisted of no prepartum supplementation (CON), 1 kg/d of DDG from d 0 to 84 (LATE84; 84 kg of DM/cow); or 2 kg/d of DDG from d 0 to 42 (LATE42; 84 kg of DM/cow). The respective weekly supplement amount was divided and offered into 3 feeding events (Monday, Wednesday, and Friday). Cow BCS were assessed on d 0, 45, 84 (calving), 140 and 224 (start and end of breeding season, respectively). Calf BW was collected at birth and weaning (d 346). Growth and reproductive data were analyzed using SAS MIXED and GLIMMIX procedures, respectively. Cow BCS from d 45 to 224 did not differ between LATE84 and LATE42 cows (P ≥ 0.20) but was always the least (P ≤ 0.05) for CON cows. Calving date, calf birth BW, and percentage of pregnant cows on d 283 did not differ (P ≥ 0.19) among treatments. Calf pre-weaning ADG and BW at weaning did not differ (P ≥ 0.58) between LATE42 and CON calves, but LATE84 calves tended to have the greatest pre-weaning ADG (P = 0.10; 0.88, 0.83, and 0.82 ± 0.02 kg/d, respectively) and BW at weaning (P = 0.10; 263, 254, and 252 ± 4.4 kg, respectively). Therefore, timing of prepartum DDG supplementation did not impact cow reproductive performance. However, calf pre-weaning growth tended to be enhanced when cows received longer vs. shorter or no periods of prepartum DDG supplementation

103 Puberty induction protocol, but not supplement amount, overcomes the negative impacts of reduced frequency of supplementation on reproduction of beef heifers

This study evaluated the performance of Bos indicus-influenced beef heifers submitted to a puberty induction protocol and offered two supplementation amounts and delivery frequencies. Sixty-four Brangus crossbred heifers were stratified by BW and age (244 ± 4 kg; 311 ± 18 d) and assigned into 1 of 16 bahiagrass pastures on d 0. Treatments were randomly assigned to pastures in a 2 × 2 factorial design (4 pastures/treatment) and consisted of soyhulls-based supplementation at 1.25% or 1.75% of BW (DM basis) offered daily or 3 times weekly for 168 d. The puberty induction protocol consisted of CIDR insert on d 56 and removal on d 70, 5-mL PGF2a injection on d 86, 2-mL GnRH injection and timed-AI on d 89. Heifers were exposed to Angus bulls from d 89 to 167 (1 bull/pasture). Pregnancy diagnosis was assessed on d 212. Frequency × rate effects were not detected (P ≥ 0.19) for any variable. Reducing the supplementation frequency from daily to 3X weekly tended (P = 0.07) to decrease overall ADG and puberty attainment on d 56 (53 vs. 41 ± 6%), but not puberty attainment on d 89 (P = 0.45; 84 vs. 78 ± 6%) and pregnancy percentage on d 212 (P = 0.97; 69 vs. 69 ± 7%). Increasing the supplement amount from 1.25% to 1.75% of BW increased (P = 0.04) overall ADG, tended (P = 0.09) to hasten puberty attainment on d 56 (40 vs. 54 ± 6%) and d 89 (74 vs. 88 ± 6%), and enhanced (P = 0.03) pregnancy percentage on d 212 (53 vs. 80 ± 7%). Therefore, the inclusion of a puberty induction protocol, but not increasing the supplement amount, enabled a reduced frequency of supplementation (3 vs. 7 times weekly) without detrimental impacts on percentage of pregnant yearling beef heifers.

164 Effects of year-round supplementation of sugarcane molasses/urea or range cubes on growth performance of Bos indicus-influenced beef cows and their offspring

This study compared the effectiveness of liquid sugarcane molasses/urea or wheat middlings-based range cubes supplementation on performance of beef cow-calf pairs. On d 0, 82 mature pregnant Brangus cows were stratified by BW and BCS (433 ± 47 kg; BCS = 4.6 ± 0.77) and randomly allocated into 1 of 6 bahiagrass pastures (13–14 pairs and 9.3 ha/pasture). Treatments were assigned randomly to pastures (2 pastures/treatment) and consisted of cows offered: winter supplementation of molasses/urea from calving until end of breeding season (d 161 to 300; MOL-W), or year-round supplementation of liquid urea/molasses (MOL-Y) or range cubes (CUB-Y). Supplement amount offered to cows differed monthly among treatments, but all cows were limit-fed 272 kg/yr of the respective supplement DM and similar trace mineral supplementation (336 g/cow/wk). Cubes were formulated to be isocaloric and isonitrogenous compared with molasses/urea (75% TDN, 20% CP; DM basis). Weekly supplement amount was divided in half and offered every Monday and Thursday. Cow BCS: did not differ among treatments from d 0 to 74 (P ≥ 0.56); was greater at calving (d 161) for MOL-Y and CUB-Y vs. MOL-W cows (P ≤ 0.05); and was greatest, intermediate, and least at start of breeding season (d 217) for MOL-Y, CUB-Y, and MOL-W cows (P ≤ 0.05), respectively. Liver concentrations for Co, Se, and Cu on d 122 and 217 were greater (P ≤ 0.02) for CUB-Y vs. MOL-W and MOL-Y cows. Calving date, percentage of pregnant cows on d 360, and calf birth BW, pre-weaning ADG, and BW at weaning did not differ (P ≥ 0.14) among treatments. Therefore, year-round supplementation of liquid molasses/urea and range cubes enhanced cow BCS at calving and start of breeding season but did not impact subsequent reproductive performance of cows and calf weaning weights than conventional winter molasses/urea supplementation of cows