The Effects of Long-term Molybdenum Exposure in Drinking Water on Molybdenum Metabolism and Production Performance of Beef Cattle Consuming a High Forage Diet

Fifty-four multiparous beef cows with calves were used to evaluate the effects of Mo source (feed or water) on reproduction, mineral status, and performance over two cow-calf production cycles (553 days). Cows were stratified by age, body weight, liver Cu, and Mo status and were then randomly assigned to one of six treatment groups. Treatments were (1) negative control (NC; basal diet with no supplemental Mo or Cu), (2) positive control (NC + Cu; 3 mg of supplemental Cu/kg DM), (3) NC + 500 µg Mo/L from Na2MoO4·2H2O supplied in drinking water, (4) NC + 1000 µg Mo/L of Na2MoO4·2H2O supplied in drinking water, (5) NC + Mo 1000-water + 3 mg of supplemental Cu/kg DM, and (6) NC + 3.0 mg of supplemental Mo/kg diet DM from Na2MoO4·2H2O. Animals were allowed ad libitum access to both harvested grass hay (DM basis: 6.6% crude protein; 0.15% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg) and water throughout the experiment. Calves were weaned at approximately 6 months of age each year. Dietary Cu concentration below 10.0 mg Cu/kg DM total diet reduced liver and plasma Cu concentrations to values indicative of a marginal Cu deficiency in beef cows. However, no production parameters measured in this experiment were affected by treatment. Results suggest that Mo supplemented in water or feed at the concentrations used in this experiment had minimal impact on Cu status and overall performance.

PSIV-10 Effects of chronic molybdenum exposure in drinking water or feed on molybdenum and copper status and production performance of gestating and lactating beef cattle consuming a low-quality forage diet

The objective of this experiment was to evaluate the effects of Mo source (feed or water) on performance and mineral status of cows and calves fed a forage-based diet for two years (DM basis: 6.6% CP; 0.14% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg). Fifty-four cow-calf pairs were stratified by cow age, BW, and liver Cu and Mo status, and randomly assigned to one of six treatments. Treatments consisted of: 1) Negative control (NC; no supplemental Mo or Cu); 2) Positive control [PC: NC + Cu (3 mg Cu/kg diet DM from CuSO4·5H2O)]; 3) NC + 500 µg Mo/L from MoNa2O4·2H2O in drinking water (Mo 500-water); 4) NC + 1000 µg Mo/L of MoNa2O4·2H2O in drinking water (Mo 1000-water); 5) Mo 1000-water + 3 mg Cu/kg diet DM from CuSO4·5H2O (Mo 1000-water+Cu); and 6) NC + 3 mg Mo/kg diet DM from MoNa2O4·2H2O (3.0 Mo-diet). Cattle were allowed ad-libitum access to feed, water, and a protein supplement throughout the experiment. During the winter months animals were housed in three replicate pens per treatment and during the summer months animals were housed in separate pastures by treatment where cow and calf feed and water intake could be measured separately. Data were analyzed as a completely randomized block design. Throughout the experiment no signs of molybdenosis were observed. There was a treatment x time (P < 0.01) interaction for cow liver Cu concentrations. Cows not receiving supplemental Cu had lower (P < 0.01) liver Cu concentrations than cows receiving supplemental Cu. Cow and calf performance, calf mineral status, cow liver Mo, and plasma and milk Mo and Cu concentrations were similar across treatments. These data indicate that Mo supplemented in water or feed at concentrations used in this experiment had minimal impact on Cu status and overall animal performance.

Molybdenum Exposure in Drinking Water Vs Feed Impacts Apparent Absorption of Copper Differently in Beef Cattle Consuming a High-Forage Diet

Twelve Angus steers were utilized to investigate the influence of molybdenum (Mo) in drinking water or feed on apparent absorption and retention of copper (Cu) and Mo. Steers were fed a low-quality grass hay diet for 14 days. Steers were then housed in individual metabolism stalls and blocked by body weight and dry matter intake (DMI) and randomly assigned within block to one of three treatments. Treatments consisted of (1) control (no supplemental Mo), (2) 5.0 mg Mo/kg DM from sodium molybdate dihydrate (Mo-diet), and (3) 1.5 mg Mo/L from sodium molybdate dihydrate delivered in the drinking water (Mo-water). Total fecal and urine output were then collected for 5 days. Dry matter, Cu and water intake, and DM digestibility were similar across treatments. Molybdenum intake was greater (P < 0.05) in Mo-water and Mo-diet steers when compared to controls but similar between Mo-water and Mo-diet steers. Apparent absorption and retention of Cu were greater (P < 0.05) in controls when compared to Mo-diet supplemented steers. Apparent absorption and retention of Cu in steers in the Mo-water treatment did not differ from controls or those receiving the Mo-diet. Molybdenum-diet and Mo-water supplemented steers had similar apparent absorption and retention of Cu. Apparent absorption and retention of Mo (% of Mo intake) was greater in controls when compared to Mo-supplemented steers. These data indicate that Mo consumed in water may impact Cu absorption and retention to a lesser extent than Mo supplemented in the diet.

PSXII-12 The influence of long-term molybdenum supplementation (in drinking water or feed) on beef calf performance through weaning

Fifty-four multiparous beef cows were used to examine the effect of molybdenum (Mo) supplemented in drinking water or feed on offspring performance. Cows were blocked by body weight (BW) and age into one of 6 groups. Group were then randomly assigned to treatment. Treatments consisted of: 1) Control (no supplemental Mo or Cu), 2) Control+Cu (3 mg Cu/kg DM from CuSO4·5H2O added to the basal diet), 3) Control + 500 µg Mo/L from MoNa2O4·2H2O in drinking water (Mo 500-water), 4) Control + 1000 µg Mo/L of MoNa2O4·2H2O in drinking water (Mo 1000-water), 5) Mo 1000-water plus 3 mg Cu/kg DM from CuSO4·5H2O added to the basal diet (Mo 1000-water+Cu, and 6) Control plus 3 mg Mo/kg DM from MoNa2O4·2H2O added to the basal diet (3.0 Mo-diet). Cows were housed in dry lot pens (n = 3 cows/pen; 3 pens/treatment) and fed a low-quality grass hay diet (DM basis: 6.6% CP; 0.14% S, 6.2 mg Cu/kg, 2.3 mg Mo/kg) and a protein supplement (30% CP). Cows received their respective treatments beginning 60 d prior to breeding and remained on treatments until all calves were weaned at approximately 7 mo. of age. Calf birth weights were collected on the day of birth and all calves were weaned on the same day. Data were analyzed using a mixed effects model for a completely randomized block design. Birthweight, ADG, and 205d adjusted weaning weights were similar (P &gt; 0.05) across treatments. These data indicate that Mo supplemented in the drinking water or the diet regardless of the inclusion of additional Cu did not impact calf performance through weaning.

PSXI-34 Supplementation of grazing Nellore beef heifers during mid-to-late gestation as a strategy to improve skeletal muscle development of the offspring

The aim of this study was to evaluate supplementation effects of grazing heifers during mid-to-late of gestation on skeletal muscle development and performance of the progeny until weaning. One hundred and eighty Nellore beef heifers confirmed pregnant (timed AI) to a single sire were allotted to a completely randomized design with 2 treatments. Ninety heifers were fed only mineral (control) and the other 90 were fed a protein supplement (44.5% CP, 0.15% BW) from 90 to 274 days of gestation. Cows were grazed on Urochloa brizantha cv. Marandu pastures (5% CP and 64% NDF). At calving, cow–calf pairs were commingled and grazed on the same pasture until weaning. At 30 days after birth, a biopsy was performed to obtain samples of skeletal muscle tissue (Semitendinosus) from calves to determine the number and size of muscle fibre. Least squares mean for all data were computed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC). Calves from heifers supplemented with protein had greater birth BW (P &lt; 0.001), ADG (P = 0.0147) and BW at 155 d (P = 0.0016) compared with calves from heifers not supplemented. However, calf BW at weaning (P = 0.1508) and gain from birth to weaning (P = 0.1446) did not differ. On the other hand, calves born from dams supplemented with protein had greater muscle fibre number (P = 0.0262), larger diameter of the fiber (P &lt; 0.001), and smaller diameter of the fiber (P &lt; 0.001) compared with calves from heifers not supplemented, although did not differ for mean fiber diameter (P = 0.8079). Fiber volume, fiber perimeter, and volume/area ratio were also affected (P &lt; 0.001) by prepartum supplementation, and were greater on calves whose dams were fed with protein. In conclusion, supplementation of pregnant Nellore heifers with protein during the dry season improves calf birth BW, and promotes hyperplasia and hypertrophy in the skeletal muscle of the offspring.

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Free gossypol supplementation frequency and reproductive toxicity in young bulls

The aim of the present study was to analyze seminal quality of young bulls subjected to different frequencies of gossypol supplementation. Forty-eight Nellore bulls, with 19 months of age and weighing 357.8 ± 7.2 kg, were used in this study. Animals were fed with 10.5 kg of standard supplement containing free-gossypol from whole cottonseed (WCS) at the following frequency: 3x/week (G3x), 5x/week (G5x) or 7x/week (G7x - Control). Additionally, a negative control was provided, and the treated animals received only mineral supplement (MM) ad libtum. The experiment lasted for 84 days and semen was collected at the beginning and at the end for analysis and cryopreservation. Fresh semen was used for initial analysis and plasma membrane integrity and sperm morphology were also determined. General motility using computer assisted sperm analysis (CASA), plasma and acrosomal membranes integrity, mitochondrial activity, and induced oxidative stress were assessed in post-thawed semen. The study design was completely randomized. Parametric data were analyzed by ANOVA and non-parametric data by the Wilcoxon test, using the statistical program SAS. Level of significance was set at 5%. Supplementation with WCS, regardless the frequency, increased total (P = .009) and head (P = .005) defects in comparison to animals receiving only forage and mineral supplement. Infrequent supplementation, particularly 5 times in the week (G5X), increased head (P = .026) and midpiece (P = .014) abnormalities. Sperm motility in fresh semen was lower in animals that received daily supplementation than those supplemented on alternate days (P = .021). Additionally, animals supplemented daily showed lower percentage of spermatozoa with intact acrosome compared to those supplemented on alternate days (P = .005). Thus, regardless the frequency of supplementation, free-gossypol supplementation affects sperm quality. Although the amount of free gossypol supplied weekly was the same among treatments, daily supplementation compromised sperm kinetics, differently from infrequent supplementation that led to sperm defects developed during spermatogenesis.

Performance, hepatic function and efficiency of nutrient utilisation of grazing dairy cows supplemented with alkaline-treated Jatropha curcas L. meal

Jatropha meal is an emergent source of protein for ruminant feed, but the presence mainly of phorbol esters limits its use. We hypothesised that alkaline treatment of Jatropha curcas L. meal will reduce phorbol esters and allow its use as a concentrate supplement for dairy cows. We evaluated the effects of four levels of Jatropha meal treated with 70 g of sodium hydroxide/kg [JMT; 0.145 mg phorbol ester g/kg dry matter (DM)] in a concentrate supplement (0, 100, 200 and 300 g/kg DM; 4 kg cow/day as fed) on performance and efficiency of nutrient utilisation in grazing dairy cows. The alkaline treatment reduced the phorbol esters content of the toxic Jatropha meal by 67.7%. The JMT level linearly reduced the supplement intake (P < 0.01), but it did not affect pasture intake (P = 0.73) or blood hepatic transaminase (P > 0.10). As a result, the JMT level linearly reduced apparent total-tract nutrient digestibility (P ≤ 0.05), ruminal microbial protein synthesis (P = 0.05) and milk yield (P < 0.01). However, it did not affect milk composition (P > 0.05) and nitrogen balance (P = 0.29). Alkaline treatment substantially reduces the phorbol ester in Jatropha meal by 67.7%, but its inclusion in supplements reduces diet digestibility and performance of dairy cows.

Suitable strategy to improve nitrogen utilization and reduce the environmental impact of Nellore bulls supplemented on tropical pasture

Expansion of the biodiesel industry has increased the crude glycerin (CG) supply. Crude glycerin has the potential of replacing corn in ruminant diets because the glycerol can be converted to glucose in the liver of ruminants, providing energy for cellular metabolism. The objective was to evaluate the effects of CG with urea, soybean meal, cottonseed meal, and corn gluten feed, respectively, on intake, digestibility, microbial protein yield, and efficiency of N utilization. Five Nellore bulls (initial BW of 448 kg [SD 14]) grazing tropical pasture were used in a 5 × 5 Latin square design. The supplements were control (no supplementation; only free-choice mineral mixture ad libitum), CG with urea (CG-Urea), CG with soybean meal, CG with cottonseed meal, and CG with corn gluten. Crude glycerin was used in all supplements to replace corn (15% of DM supplement). There were differences between CG-Urea and other supplements with regard to intake of DM (% of BW and total; < 0.01), OM ( < 0.01), CP ( < 0.01), and TDN ( < 0.01). The digestibility of CP was greater ( = 0.04) for animals supplemented with CG-Urea than for those fed other supplements. Animals supplemented with CG-Urea showed greater N intake ( < 0.01) and N ammonia ( = 0.04) than those supplemented with other treatments. Nitrogen retained (g/d) was not affected by protein source but was greater for cattle fed a protein supplement compared with cattle fed the control supplement ( < 0.01). Supplementing the animals with protein sources increased ( = 0.02) the daily production of rumen microbial nitrogen (g/d) compared with the control group. Microbial protein (g/d) was lesser for the control than for protein sources ( = 0.02). However, when expressed relative to TDN ( = 0.35) and CP ( = 0.82), there were no differences across treatments. Crude protein intake per digestible OM intake (g CP/kg digestible OM intake) was greater for animals fed protein sources compared with animals fed control supplements ( < 0.01). Based on nutrients intake and microbial protein yield, CG-Urea supplement has a greater feeding value compared with other protein sources. Crude glycerin, when used to replace corn in 15% of DM supplement, may be effective to improved N utilization and microbial protein yield in rumen of Nellore bulls grazing cv. Marandu.