Application of fecal near-infrared reflectance spectroscopy profiling for the prediction of diet nutritional characteristics and voluntary intake in beef cattle

The objective of this study was to evaluate the use of fecal near-infrared reflectance spectroscopy (NIRS) profiling to predict diet nutritional characteristics and voluntary DMI in beef cattle. Fecal samples were collected for growing cattle across 11 experiments in which individual animal performance and DMI was measured. Dried and ground fecal composite samples collected from each animal were subjected to fecal NIRS analysis by a Foss NIRS 6500 scanning monochromator (Foss, Eden Prairie, MN) at the Grazingland Animal Nutrition Laboratory (Temple, TX). Fecal spectra were then used to develop equations to predict diet composition (trials 1 to 11; = 408), digestibility (trials 1 to 5; = 155), and DMI (trials 1 to 11; = 408). Coefficients of determination for calibration () and cross-validation () for prediction of diet nutritional characteristics were lower for NDF ( = 0.85; = 0.82) than for CP ( = 0.90; = 0.88). For the prediction of DMI, and ranged from 0.69 and 0.67 for the prediction of trial-average DMI to 0.76 and 0.73 for the prediction of fecal-collection-period DMI. While the and obtained for the prediction of DMI were lower than those obtained for the prediction of diet composition or digestibility, fecal NIRS prediction equations for DMI were successful in predicting the mean DMI of groups, as no differences were found for the prediction of fecal-collection-period DMI (Diff. = 1.10; = 0.72) or trial DMI (Diff. = -0.47; = 0.86).

Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers

Manafiazar, G., Basarab, J. A., Baron, V. S., McKeown, L., Doce, R. R., Swift, M., Undi, M., Wittenberg, K. and Ominski, K. 2015. Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers. Can. J. Anim. Sci. 95: 369–381. There is limited knowledge of how cattle tested for feed efficiency under drylot conditions perform when they graze on summer pasture. Residual feed intake adjusted for end of test backfat thickness (RFIfat) was determined on 171 beef crossbred heifers under drylot conditions over 2 yr using an automated system. Upon completion of the test, the 10 lowest and 10 highest RFIfat (–0.54±0.17 vs. 0.58±0.15 kg DM d−1) heifers in 2012, and the 14 lowest and 14 highest RFIfat (−0.47±0.16 vs. 0.53±0.19 kg DM d−1) heifers in 2013 were selected and placed on meadow bromegrass pasture to investigate the effect of RFIfat ranking on their grass intake and performance on the pasture. The pasture adaptation period (8 d in 2012 and 19 d in 2013) was followed by a pasture feed intake experiment during which heifers were dosed twice daily (0815 and 1415) with 500 g of C32-labeled feed pellet for 13 d (day 0 to 12) and fecal sampled twice daily (0815 and 1415) from day 8 to 12. Forage DM intake on pasture for each heifer was determined using the double alkane (C31/C32) methodology. High and low RFIfat heifers were similar in body weight (BW), backfat and rump fat thickness, and average daily gain (ADG) during the grazing trial period, except backfat thickness at the end of test period. However, low RFIfat heifers consumed 5.3% less forage when expressed as kg DM d−1 (8.20±0.08 vs. 8.66±0.09, P<0.001) and 5.1% less when expressed as a percentage of body weight (1.86±0.02 vs. 1.96±0.02% of BW, P<0.001) compared with high RFIfat heifers. RFIfat measured under drylot conditions in growing heifers was positively correlated to grazed RFIfat determined in pregnant heifers (rp=0.30, P=0.04). These results suggest that beef heifers classified as low RFIfat during the post-weaning drylot period had lower dry matter intake as heifers in their first pregnancy grazing tame pasture, with no negative impact on their body weight, back-fat thickness, and ADG compared with their high RFIfat herdmates.

Impact of prolonged cold exposure on dry matter intake and enteric methane emissions of beef cows overwintered on low-quality forage diets with and without supplemented wheat and corn dried distillers’ grain with solubles

Bernier, J. N., Undi, M., Plaizier, J. C., Wittenberg, K. M., Donohoe, G. R. and Ominski, K. H. 2012. Impact of prolonged cold exposure on dry matter intake and enteric methane emissions of beef cows overwintered on low-quality forage diets with and without supplemented wheat and corn dried distillers’ grain with solubles. Can. J. Anim. Sci. 92: 493–500. This study was conducted to determine the impact of prolonged cold exposure on dry matter intake (DMI) and enteric methane (CH4) emissions of overwintering beef cows consuming low-quality forage with and without supplemented protein in the form of dried distillers’ grain with solubles (DDGS). The study was carried out with 30 mature, dry, open beef cows (663±52.9 kg) that were fed a low-quality (deficient CP, 6.0% CP) forage (control), low-quality forage supplemented with 10% DDGS (sufficient CP, 8.7% CP; DDGS10) or 20% DDGS (excess CP, 11.6% CP; DDGS20). Carrying out the study from October through February allowed assessment under thermal neutral and prolonged cold conditions typical of the prairie region of Canada (Manitoba, Alberta and Saskatchewan). Average minimum and maximum daily temperatures were 2.7 and 13.8°C in the thermal neutral period, and –23.5 and −11.0°C in the prolonged cold period, respectively. When no protein supplements were offered, cows exposed to prolonged cold consumed less (P=0.01) forage than when exposed to thermal neutral conditions. Enteric CH4 emissions, when measured as litres per day, were not influenced (P>0.05) by dietary protein supplementation, averaging 285.6±11.71, 311.9±11.49 and 282.6±13.02 L d−1 for cows fed control, DDGS10, and DDGS20 diets, respectively. When expressed as a percentage of energy consumed, cows consuming low-quality forage supplemented with 20% DDGS produced 18.5% less (P=0.01) enteric CH4 relative to cows consuming the low-quality forage only, with emissions of 5.3±0.38 and 6.5±0.33% GEI, respectively. Mature beef cows maintained at the same physiological status and dietary regime produced 26.8% less (P=0.001) enteric CH4 (7.1±0.30 vs. 5.2±0.26% GEI) under prolonged cold as compared with thermal neutral conditions. Based on these results, enteric CH4 emissions for the Canadian cow herd that is overwintered outdoors may be overestimated using current International Panel on Climate Change (IPCC) methodology.

Pasture productivity, cattle productivity and metabolic status following fertilization of a grassland with liquid hog manure: A three-year study

Forage yield and quality, cattle and pasture productivity, and enteric methane (CH4) emissions were determined from grass pastures receiving liquid hog manure. Three treatments were evaluated: grass pastures receiving no manure (Control), grass pastures receiving liquid hog manure applied as a single application of 142 ± 20 kg available N ha-1 in the spring (Single) or a split application of 70 ± 6 kg available N ha-1 in both the spring and autumn (Split). Each treatment was represented by two paddocks. The study was carried out over three grazing seasons, from 2004 to 2006, with each grazing season divided into three, 28-d periods. Growing steers (338 ± 32 kg) were introduced into pastures in early summer (May-June) of each year. Standing biomass, measured using quadrats, averaged 1.2, 2.6, and 2.0 ± 0.44 t dry matter (DM) ha-1 for Control, Split and Single pastures, respectively, and was not influenced (P = 0.13) by liquid hog manure application. Liquid hog manure application caused a shift in pasture grasses resulting in a predominance of quackgrass [Elytrigia repens (L.) Nevski]. Nutrient profiles of forage samples collected by hand plucking showed no treatment response for forage gross energy (GE; P = 0.18) and neutral detergent fibre (NDF; P = 0.19), but forage crude protein (CP) (P = 0.027) as well as ash (P = 0.002), K (P = 0.001), P (P = 0.001), and Mg (P = 0.001) concentrations increased with manure application. Liquid hog manure application did not influence dry matter intake (DMI) (P = 0.56), GE intake (P = 0.58), and NDF intake (P = 0.79) of grass forages. Higher CP intake of steers on Split and Single pastures resulted in higher (P = 0.001) serum urea N (5.7 and 5.9 ± 0.42 mmol L-1, respectively) compared with steers grazing Control pastures, 2.5 ± 0.42 mmol L-1. Enteric CH4 emissions (L d-1) tended to be lower (P = 0.09) in cattle grazing the Split pasture treatment. Though application of liquid hog manure did not improve individual animal gains, pasture carrying capacity increased (P = 0.001) from 89 to 324 grazing days ha-1 and liveweight gain increased (P = 0.001) from 100 to 329 kg ha-1 in Control and manured pastures, respectively. Application of liquid hog manure to grasslands generated significant benefits through improved forage quality and pasture productivity measured as carrying capacity and liveweight gain. Split liquid hog manure application may have a further benefit in terms of improved carrying capacity and lower enteric CH4 emissions. Key words: Liquid hog manure, enteric methane, beef cattle, carrying capacity, serum urea nitrogen

Comparison of techniques for estimation offorage dry matter intake bygrazing beef cattle

Four techniques were compared for their ability to estimate forage dry matter intake (DMI) of grazing animals. In the Cage technique, 10 grazing cages were placed within each pasture, and forage inside and outside the cages was clipped from 0.25-m2 quadrats after 12 to 20 d of grazing. The difference between forage inside and outside the grazing cage represented forage consumed by grazing animals. The second technique used n-alkane controlled release capsules to measure DMI of individual grazing animals (N-alkane marker technique). The remaining two techniques were prediction equations; one utilized body weight (BW) and average daily gain (ADG) to estimate DMI (Minson equation) and the other related dietary net energy concentration and BW to DMI (Net Energy equation). The four methodologies were applied to a 3-yr study evaluating liquid hog manure on the productivity of grass pastures. The study utilized steers of a relatively uniform body size on six continuously grazed grass pastures. When individual animal intakes were compared, the Net Energy equation estimated lower (P < 0.05) DMI than the Minson equation, with the N-alkane marker technique being intermediate. Dry matter intake (mean ± SD, kg d-1) was 5.3 ± 0.76, 7.4 ± 1.86, and 6.5 ± 2.58 for the Net Energy equation, Minson equation, and N-alkane marker technique, respectively. The Cage technique estimated average DMI of animals in each pasture of 17.5 ± 11.61 kg d-1 and this was higher (P < 0.05) than estimates from the other techniques. Dry matter intake estimates from different techniques were ranked: Cage technique > Minson equation > N-alkane marker technique > Net Energy equation. The DMI estimates generated by the Cage technique were associated with the largest coefficient of variation, with extreme values representing a range from 0.3 to 15.2% BW. The N-alkane marker technique estimated DMI that ranged from 0.6 to 4.5% BW. The strongest correlation (r = 0.30; P = 0.001) in DMI estimates was between the Net Energy and Minson equations due to the inclusion of BW as a component in both equations. Results of this study suggest that prediction equations can be useful for rapid DMI estimation. The N-alkane marker technique may be the preferred technique when a wide range of pasture conditions is anticipated. Key words: Grazing cages, n-alkanes, prediction equations, dry matter intake, grazing animals

Estimation of carbon dioxide production and energy expenditure of grazing cattle by the sulphur hexafluoride (SF6) tracer gas technique

The purpose of the study was to explore the suitability of the sulphur hexafluoride (SF6) tracer gas technique to estimate CO2 production and energy expenditure (EE) for grazing animals on pastures typical of western Canada. During each year of a 3-yr study, CO2 emissions were collected from 60 yearling steers on grass pastures receiving one of three fertility treatments: no manure, liquid hog manure applied as a split application (74 kg available N ha-1) in the spring and fall, and a single application of liquid hog manure applied at a rate of 155 kg available N ha-1 each spring. The mean CO2 production estimate across all treatments was 5424 ± 2218 L d-1 (mean ± SD) with a range of 1099 to 11548 L d-1. When compared across three grazing periods in June, July and August, steers produced more (P < 0.05) CO2 in June than in either July or August. Metabolic body weight (BW0.75), average daily gain (ADG), standing forage biomass, and forage neutral detergent fibre (NDF) and crude protein (CP) contents explained 33% of the variation in CO2 production. Energy expenditure (EE) was estimated from CO2 production by adopting an energetic equivalent of 22 kJ L-1 CO2 and EE was calculated for animals that were not losing body weight at time of measurement. The average EE estimate was 1.2 ± 0.5 MJ kg-1 BW0.75 d-1 with a range of 0.2 to 2.8 MJ kg-1 BW0.75 d-1. Energy expenditure declined as ADG and forage biomass declined, but EE was not influenced (P > 0.05) by fertility treatment. The EE estimate was higher (P < 0.05) early in the grazing season (June) and declined as the grazing season progressed. The SF6 tracer gas technique was able to estimate EE of individual animals without interfering with herd dynamics. The technique was also able to show differences in EE in response to pasture conditions. The results of this study suggest that the SF6 tracer gas technique shows potential as a simple and non-invasive method of estimating CO2 production and EE for grazing animals. Further validation under different grazing conditions and with animals undertaking different degrees of activity is required. Comparisons with other field techniques of estimating EE are also important. Key words: Energy expenditure, carbon dioxide, sulphur hexafluoride, grazing animals

Nutritive value of maize stover/pasture legume mixtures as dry season supplementation for sheep

Two experiments were carried out to determine the nutrient contents and relative preferences of maize stover and three legumes forages and their feeding on intake and digestibility of sheep. Maize stover was blended with three legumes, stylo (Stylosanthes guainensis), siratro (Macroptilium atropurpureum) and centro (Centrocema pubescens), to produce four treatments, namely, only maize stover (control), stover/stylo, stover/siratro and stover/centro mixtures. The first experiment evaluated the relative preference of the stover and the various stover/legume mixtures when offered to sheep. Six rams were offered pair combinations of the treatments in a 6x6 Latin square with a split plot arrangement such that each ram had access to two feeds at a time in each period of 6 days. The second experiment included measurements of intake and digestibility of the stover and stover/legume mixtures. Four intact and four castrated male sheep were used in two, 4x4 Latin squares with 21-day periods. The least (P<0.05) preferred feed was maize stover when it was offered as the sole feed. There were no significant differences in preference among the stover/legume mixtures. Dry matter intake (DMI) was highest (P<0.05) when sheep were offered the stover/centro mixture and lowest (P<0.05) when maize stover was fed as the sole feed. Dry matter digestibility did not differ significantly among treatments. Sheep that were offered maize stover only lost weight, those fed stover/centro gained weight and those that were fed either stover/siratro or stover/stylo maintained weight. However, these short-term weight changes may reflect changes in fill as much as changes in body tissue. Addition of legumes to maize stover improved the nutritive value, possibly by increasing the nitrogen content of the stover. The results suggest that maize stover, which is normally left to rot in the field, could be better utilised by intercropping with legumes and allowing animals access after grain harvest.

Occurrence of fungal species in stored alfalfa forage as influenced by moisture content at baling and temperature during storage

A study was conducted to evaluate the effect of moisture content at baling on fungal growth during storage of alfalfa forage. Alfalfa forage was baled at DM contents of 64.1–66.2% (Low), 71.9–73.2% (Medium) and 75.4–77.4% (High) and was sampled 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 21, 35 and 60 d after storage. For each sample, abundance of fungal and yeast species was assessed by plating on media. Total fungal counts, number of species, species diversity, and species dominance were subjected to analysis of variance, and variation in the fungal assemblages was characterized by ordination. Total fungal counts, number of species, species diversity, and species dominance were not influenced (P > 0.05) by moisture content in the early (days 1 to 8) storage phase. Moisture content at baling did influence (P < 0.05) total counts, number of species, and species dominance in the latter phase (days 9 to 60) of storage. Total fungal counts were highest in Low DM forage, and number of species highest in Medium DM forage. Species dominance was highest in High DM forage. Low DM forage was associated with Aspergillus fumigatus, Mucor spp., Absidia spp., Emericella nidulans, and thermotolerant hyphomycetes. Aspergillus repens, Absidia spp. and some yeasts were more predominant in Medium and High DM forages. Moisture content and temperature were related to species assemblages during storage but water-soluble carbohydrate concentration, crude protein concentration and total bacteria counts were not. "Field" fungi, Phoma, Alternaria, Cladosporium spp. and most yeasts were eliminated within 8 d of storage. Physical conditions created in the early stages of storage likely affected fungal growth in the later storage phase. Key words: Moisture content, temperature, storage, alfalfa hay, fungal species, diversity

Effect of dry matter content at baling on change in forage constituents during the storage of alfalfa hay

The purpose of this study was to evaluate the effect of DM content at baling on the pattern of forage constituent change and on DM and nutrient losses during storage. Alfalfa forage, baled at 64.1–66.2, 71.9–73.2 and 75.4–77.4% DM, was designated Low, Medium, and High DM treatments, respectively. Hay generated from each treatment was stored in a pole structure as two 74-bale stacks per treatment, using a bale wagon. Core samples were collected from bales on days 1, 4, 7, 14, 21, and 60 of storage. Bale temperature was monitored for eight bales per treatment daily for the first 35 d of storage and then on days 45, 50, and 60. Peak storage temperature reached was influenced (P < 0.05) by forage DM at baling; the highest peak temperature being associated with Low DM hay. DM losses also were higher (P < 0.05) in Low DM hay relative to either Medium or High DM hays, averaging 10.1, 4.5, and 3.0%, respectively. Dry matter (DM), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent insoluble nitrogen (ADIN), and glucosamine contents increased in all forage treatments during storage; the extent of increase was more (P < 0.05) in Low DM hay than in High DM hay. Cellulose, lignin and crude protein (CP) concentrations followed a similar pattern during storage for hay baled and stored at the three DM contents. Soluble carbohydrate content loss was higher (P < 0.05) in Low DM hay relative to High DM hay. Forage DM content at baling will influence stack temperatures and extent of nutrient change during storage. Most changes m constituents of low DM hay occurred within the first 14 d of storage, a period within which peak temperatures were recorded in all forages. The study also showed that alfalfa forage can be stored at a DM content of 76% with minimal nutrient change and loss, which is lower than normally recommended. Key words: Alfalfa hay, storage, nutrients, DM contents, temperature

Production responses by early lactation cows to whole sunflower seed or tallow supplementation of a diet based on barley

A 2-yr study to evaluate the effectiveness of whole sunflower seed as a source of fat was conducted with 18 primiparous and 31 multiparous Holstein cows. The three diets evaluated were a basal diet based on barley (control), a basal diet supplemented with 2.7% tallow, and a basal diet supplemented with 7.1% whole sunflower seeds. The DMI of lactating cows during the 16-wk test period was not influenced by supplementation with either sunflower seeds or tallow. Milk production was 34.4, 34.6, and 35.5 kg/d for cows fed the control diet or the diets supplemented with sunflower or tallow, respectively, and was not influenced by diet. The production and concentrations of milk protein, fat, and SNF also were not influenced by diet. The concentrations of C6:0 to C14:1 fatty acids were highest in the milk of cows fed the control diet. The concentrations of C10:0 to C16:1 were higher when cows were fed the diet with the tallow supplement than when they were fed the diet with the sunflower supplement. However, the concentrations of C18:0 to C18:2 and C20:0 were higher in the milk of cows that were fed the sunflower supplement than in the milk of cows that were fed the tallow supplement or the control diet. Concentrations of individual VFA and the ratio of acetate to propionate were not influenced by diet. Body weight, body condition score, and reproduction parameters were similar for all diets, suggesting that there were no effects on subsequent production. The performance of cows fed whole sunflower seeds as a source of energy appeared to be similar to the performance of cows fed traditional high energy diets based on barley. The fatty acid profile of the milk of cows fed diets supplemented with sunflower seeds was more favorable than that of the milk of cows fed diets supplemented with tallow.

Effect of fungal biomass in moldy alfalfa hay on preference by dairy calves with no previous exposure to moldy feeds

A study of 141-kg dairy calves evaluated their preference for alfalfa hay that contained different amounts of fungal biomass, which was estimated by the glucosamine assay. Alfalfa that was harvested at different maturities and stored at varying DM contents was chopped and blended to produce four forage treatments. The four forage treatments included hay that had 1) low NDF content and a low amount of fungal biomass, 2) high NDF and low fungal biomass, 3) high NDF and moderate fungal biomass, and 4) high NDF and high fungal biomass. Forage treatments were offered in pair combinations with two feeders per calf; treatments were switched from one feeder to the other on alternate days. The four forage treatments were offered in such a way that all six pair combinations were tested in each period. Each of the two trials was designed as a 6 x 6 Latin square. Preference data were collected for the 6-d periods and were analyzed as a split plot. Difference in intake of paired forage treatments was the response variable. Hay preference declined as either fiber content of hay or amount of fungal biomass in hay increased. Forage intake of each treatment relative to mean intake was 3.3, 0.8, -0.5 and -3.7 kg/6 d for forage treatments 1, 2, 3, and 4, respectively. Low preference for molded hay would probably result in greater feed sorting and lower intakes when calves have a choice of feedstuffs.