Age Intake Research Articles

PSX-23 Predicting feedstuff associative effects in goats

Abstract The objective was to develop means of predicting effects of supplementation on forage and total ME intake in goats. A database of treatment mean observations from the literature currently has 529 individual animal observations with ad libitum intake from 24 studies. Essential data were supplement and forage OM digestibility without supplementation or sufficient information for estimation, total diet OM digestibility, forage and supplement CP concentration and OM intake, and BW. Intake of ME was assumed 15.104 MJ/kg digested OM. For observations with supplementation, forage ME intake was the difference between total and supplement ME intake. The original database had 134 observations, although 24 were omitted because of questionable values and(or) unlikely estimates. Forage averaged 9.4 MJ/kg DM of ME (SD=1.77, 4.6–12.6), 59.1% OM digestibility without supplementation (SD=8.67, 42.9–77.1; AOMDIGFOR), and 8.1% CP (SD=3.72, 2.1–17.1) (PTCPFOR), and supplement was 12.3 MJ/kg ME (SD=1.38, 7.1–15.1) and 28.4% CP (SD=41.5, 0–288). Forage ME intake (MEIMBWFOR, kJ/kg BW0.75) was regressed against supplement ME intake (MEIMBWSUP, kJ/kg BW0.75), with inclusion of other variables tested. The equation explaining most variation (R2=0.77) was 155.9 ± 135.75 – (0.5403±0.04381 × MEIMBWSUP) – (41.0063±20.71841 × PTCPFOR) + (5.3497±2.31608 × AOMDIGFOR) + (0.74056±0.345002 × PTCPFOR × AOMDIGFOR), with P values of 0.253, < 0.001, 0.050, 0.023, and 0.034, respectively. The mean difference between observed and predicted MEIMBWFOR (379±15.0 and 382±12.8, respectively) was -3±7.4, with minimum and maximum values of -181 and 167, respectively. The equation for the regression of residual MEIMBWFOR (observed – predicted) against predicted values was -10±22.3 + (0.018±0.0553 × predicted MEIMBWFOR), with the intercept and slope not different from 0 (P = 0.670 and 0.739, respectively). Equations describing associative effects can be used to predict the quantity of a particular supplement with a given forage necessary to meet nutrient requirements of goats in specific production settings.

163 The effects of energy and lasalocid supplementation on forage intake and energetics of cattle grazing wheat pasture

Abstract Cattle grazing wheat have the potential to gain BW exceptionally well, but excessive nitrogen intake results in increased excretion and increased greenhouse gas (GHG) emissions. Supplemental grain with the addition of an ionophore given to ruminants grazing wheat is a potential practice for producers to increase nitrogen efficiency while decreasing GHG emissions. Therefore, the objective of this experiment was to quantify the effects of energy and lasalocid supplementation on nutrient intake, respiratory gas fluxes, and performance of grazing cattle. Heifers (n = 18) were used in a 49-d experiment that consisted of two 21-d blocks with 7 d between them (initial BW=311±17.3 kg and 339±16.7 kg, Block 1 and 2, respectively). Heifers were assigned randomly to 1 of 3 treatments; no supplement (Control, n = 6), 2.95 kg control feed/d (Energy, n = 6), or 2.95 kg feed with lasalocid/d (Lasalocid, n = 6). Cattle grazed an 8.1-ha paddock of winter wheat and had access to a GreenFeed system used to quantify the respiratory gas fluxes (CH4, CO2, and O2). Cattle were weighed on d 0 and 21 of each block, on d 15 to 21 cattle were gathered every 12 h and fecal samples were collected. Data were analyzed using the PROC MIXED in SAS. Methane emissions were not affected (P = 0.58) by treatment, but supplemented cattle had greater (P = 0.04) CO2 emissions and O2 consumption (P = 0.03). Hence, ADG tended to be greater for supplemented cattle (P = 0.09) compared with Control (1.22 and 1.00 kg, respectively), but no effect (P = 0.88) was observed for the Lasalocid. Fecal output was greater for supplemented cattle (P < 0.01), but forage intake was lower (P < 0.01) and nutrient intake was higher (P < 0.01) for supplemented cattle compared to Control. Supplemented cattle had lower forage intake with greater CO2 emissions and O2 consumption, but the Lasalocid did not affect any parameter.

164 The effects of energy and lasalocid supplementation on forage intake and energetics of cattle grazing wheat pasture

Abstract Cattle grazing wheat have the potential to gain BW exceptionally well, but excessive nitrogen intake results in increased excretion and increased greenhouse gas (GHG) emissions. Supplemental grain with the addition of an ionophore given to ruminants grazing wheat is a potential practice for producers to increase nitrogen efficiency while decreasing GHG emissions. Therefore, the objective of this experiment was to quantify the effects of energy and lasalocid supplementation on nutrient intake, respiratory gas fluxes, and performance of grazing cattle. Heifers (n = 18) were used in a 49-d experiment that consisted of two 21-d blocks with 7 d between them (initial BW=311±17.3 kg and 339±16.7 kg, Block 1 and 2, respectively). Heifers were assigned randomly to 1 of 3 treatments; no supplement (Control, n = 6), 2.95 kg control feed/d (Energy, n = 6), or 2.95 kg feed with lasalocid/d (Lasalocid, n = 6). Cattle grazed an 8.1-ha paddock of winter wheat and had access to a GreenFeed system used to quantify the respiratory gas fluxes (CH4, CO2, and O2). Cattle were weighed on d 0 and 21 of each block, on d 15 to 21 cattle were gathered every 12 h and fecal samples were collected. Data were analyzed using the PROC MIXED in SAS. Methane emissions were not affected (P = 0.58) by treatment, but supplemented cattle had greater (P = 0.04) CO2 emissions and O2 consumption (P = 0.03). Hence, ADG tended to be greater for supplemented cattle (P= 0.09) compared to Control (1.22 and 1.00 kg, respectively); but no effect (P = 0.88) was observed for the Lasalocid. Fecal output was greater for supplemented cattle (P < 0.01), but forage intake was lower (P < 0.01) and nutrient intake was higher (P < 0.01) for supplemented cattle compared to Control. Supplemented cattle had lower forage intake with greater CO2 emissions and O2 consumption, but the Lasalocid did not affect any parameter.

197 Supplemental feeding, forage intake and animal performance – perspectives from research and the industry

Journal Article 197 Supplemental feeding, forage intake and animal performance – perspectives from research and the industry Get access Matthew Cravey Matthew Cravey Phileo Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 98, Issue Supplement_2, November 2020, Page 68, https://doi.org/10.1093/jas/skz397.159 Published: 28 November 2020

188 Voluntary individual intake and performance of mature cows compared to primiparous heifers consuming a low quality forage

Abstract This study investigated production and efficiency of Angus first-calf heifers and mature cows. During late lactation (January through April), cow/calf pairs were provided abundant bermudagrass hay and 2.5 kg of dried distiller’s grains with solubles daily. Milk yield and composition was determined monthly using a milking machine. After weaning, forty-three Angus 2-yr-old heifers (n = 22) and cows (n = 21) were assigned to one of five pens according to their dry matter intake EPD. Each pen was equipped with two SmartFeed individual intake units adapted with a hay basket. Cows had ad libitum access to long stem prairie hay (CP = 5.7%, NDF = 66.4, TDN = 54%). Cows were provided 1 kg corn and 1 kg cotton seed meal daily. Performance variables were analyzed with a mixed model including pen as a random variable and age the fixed variable. Following a 14-day adaptation period, individual cow forage intake was measured for 45 days. There was a positive phenotypic correlation (r = 0.40, P < .01) between residual average daily gain EPD and average study-period BCS on trial. Mature cows consumed 1.9 kg more forage daily (P = 0.05) than heifers although there was no difference when expressed as a percent of BW (2.0%; P > .78). There was no difference in the amount of time spent in feeders between heifers and cows (4.6 hrs, P > 0.59) nor average body condition score (5.1, P > .86). Cows produced more milk per unit of body weight (P < .01) and had greater residual feed intake and calf weaning weight (kg) compared to heifers (0.63 and 211.6 vs -0.45 and 189.3; P < 0.04). Heifers consumed similar amount of forage per unit of BW, spent the same amount of time in feeders and were more efficient in weight gain while consuming low quality forage.

127 Predicting Dry Matter Intake of Gestating and Lactating Beef Cows

Abstract In 1996, the NASEM beef cattle committee developed and published an equation to estimate cow feed intake using results from studies conducted or published between 1979 and 1993 (Nutrient Requirements of Beef Cattle). The same equation was recommended for use in the most recent version of this publication (2016). The equation is sensitive to cow weight, diet digestibility and milk yield. Our objective was to validate the accuracy of this equation using more recent published and unpublished data. Criteria for inclusion in the validation data set included projects conducted or published within the last ten years, direct measurement of forage intake, adequate protein supply, and pen feeding (no tie stall or metabolism crate data). The validation data set included 29 treatment means for gestating cows and 26 treatment means for lactating cows. Means for the gestating cow data set was 11.4 ± 1.9 kg DMI, 599 ± 77 kg BW, 1.24 ± 0.14 Mcal/kg NEm per kg of feed and lactating cow data set was 14.5 ± 2.0 kg DMI, 532 ± 116.3 kg BW, and 1.26 ± 0.24 Mcal NEm per kg feed, respectively. Non intercept models were used to determine equation accuracy in predicting validation data set DMI. The slope for linear bias in the NASEM gestation equation did not differ from 1 (P = 0.07) with a 3.5% positive bias. However, when the NASEM equation was used to predict DMI in lactating cows, the slope for linear bias significantly differed from 1 (P < 0.001) with a downward bias of 13.7%. Therefore, a new multiple regression equation was developed from the validation data set: DMI= (-4.336 + (0.086427 (BW^.75) + 0.3 (Milk yield)+6.005785(NEm)), (R-squared=0.84). The NASEM equation for gestating beef cows was reasonably accurate while the lactation equation underestimated feed intake.

52 Effects of an energy or protein supplement on forage dry matter intake for steers grazing summer native range

Abstract The objective of this study was to determine the effects of supplementation level and type on forage intake of steers grazing a high-quality native range. This study was conducted in late May through the end of June. On d 0, steers (n=16, initial BW = 193.7 kg ± 14.3 kg) were randomly assigned to one of 5 dietary treatments, fed once daily in individual stalls for 28 d. Treatments were control (no supplement, n=4), or supplemented with either cottonseed meal or dry rolled corn, each at either 0.45 kg or 1.81 kg as-fed/d (n=3 for each combination). Beginning on d 7, steers were orally administered titanium dioxide boluses (10 g/steer) once daily for 21 d. Fecal samples were collected from the rectum once daily for 14 d, analyzed for Ti concentration via a handheld X-ray fluorescence analyzer, and total fecal output was estimated. Diet digestibility was estimated after a 288-h in situ incubation of forage and fecal samples to determine indigestible NDF. Some steers had orts, therefore actual mean supplement intake was used in analysis. Results were analyzed with regression, with animal as the experimental unit. Mean estimated forage DMI of unsupplemented animals was 1.6% BW. Contrary to expectation, corn supplemented steers exhibited greater forage DMI as a percentage of BW than cottonseed meal supplemented steers (P = 0.01; 1.5 vs. 1.1, respectively).

Goat performance on pure Andropogon gayanus pastures or associated with legumes.

The objective of this study was to evaluate the grazing of goats in a grass monoculture system and in intercropping systems of grass + legumes. A randomized block design was adopted, with the treatments arranged in a split-plots scheme. The plots consisted of three cropping systems: monoculture-Andropogon gayanus cv. Planaltina; mixture I-A. gayanus cv. Planaltina+ Stylosanthes cv. Campo Grande; and mixture II-A. gayanus cv. Planaltina+ Calopogonium mucunoides. The subplots consisted of two grazing cycles. The highest (P = 0.04) total forage mass (TFM) was recorded in the mixture I (A. gayanus cv. Planaltina + Stylosanthes. cv. Campo Grande), which was 2.6 ± 0.1 tons DM/ha. The crude protein (CP) was lower in the monoculture which also showed the highest content of neutral detergent fiber (NDF). The grazing time in the monoculture was the longest (8.23 ± 1.14h). The goats used a longer time for rumination (P < 0.01) in the mixture I. The lowest (P < 0.01) bite rate was found in mixture II in comparison to the other cropping systems. The bite rate was higher (P < 0.01) in grazing cycle II than in all the other cropping systems. In mixture I, the Stylosanthes cv. Campo Grande, and in mixture II, the C. mucunoides presented the lowest (P < 0.01) δ13C value in the forage. The highest forage intake occurred in the mixture systems (P < 0.01) in comparison to the monoculture. The mixture pastures presented better results for forage mass, nutritive value, and intake in comparison to the monoculture.

Effects of supplementary feeding level on digestion and energy utilization by sheep and goats grazing arid-area rangelands

An experiment was implemented to examine differences between sheep and goats in the utilization of open arid-area rangelands when provided with different concentrate supplement levels. Fifty-two non-lactating females (Abu-duleik sheep, n = 26 and Balady goats, n = 26) were employed in a 90-day experimental period. Animals of each species were allocated randomly into two treatments, according to a 2 × 2 factorial arrangement, with animal species (goats and sheep) and concentrate level (low and high) as main factors. They were grazing widely over the arid-area rangelands with a limited amount of a concentrate supplement, low (1 % BW) or high (2 % BW) (DM basis). Total energy expenditure was estimated by heart rate (HR) monitors for 48 h after its calibration by oxygen consumption with a face mask open-circuit respiratory system. However, the significant interaction between animal species and concentrate levels of supplement indicated that increasing the concentrate level had a negative effect (P < 0.05) on forage intake (22.8 vs. 17.0 ± 1.58 g/ kg BW, for goats supplemented with low or high concentrate level, respectively) and digestibility by grazing goats. The reduction in goat’s digestibility was mainly attributed to the reduction (P < 0.01) in fiber fraction digestibility (546 vs. 441 ± 24.0 g/ kg dry matter intake, respectively). The contrary was observed in sheep in which the greatest forage consumption and digestibility were observed in grazing sheep supplemented with a high concentrate level, including the fiber fraction digestibility. Total energy expenditure was similar between sheep and goats when supplemented with a low concentrate level (600 and 574 ± 24.6 kJ/ kgBW0.75, respectively), while it was significantly (P < 0.01) greater for sheep than for goats when supplemented with a high level (776 vs. 577 ± 24.6 kJ/ kg BW0.75, respectively). This was reflected in the energy balance (EB) that was negative and similar in sheep and goats at a low supplementation level (−55.2 and −64.3 ± 14.27 kJ/ kg BW0.75, respectively, while sheep reported positive (P < 0.05) and greater EB than that of goats with a high level (71.5 vs. 2.7 ± 14.27 kJ/ kg BW0.75, respectively). In conclusion, concentrate supplement is necessary to maintain animals without nutritional deterioration while grazing in the open arid-area rangelands, however, its effects on the ability to utilize a low quality forage differed between sheep and goats at a high supplementation level.

Nutritional Quality, Voluntary Intake and Enteric Methane Emissions of Diets Based on Novel Cayman Grass and Its Associations With Two Leucaena Shrub Legumes.

Methane (CH4) emissions from enteric fermentation in cattle are an important source of greenhouse gases, accounting for about 40% of all agricultural emissions. Diet quality plays a fundamental role in determining the magnitude of CH4 emissions. Specifically, the inclusion of feeds with high digestibility and nutritional value have been reported to be a viable option for reducing CH4 emissions and, simultaneously, increase animal productivity. The present study aimed to evaluate the effect of the nutritional composition and voluntary intake of diets based on tropical forages upon CH4 emissions from zebu steers. Five treatments (diets) were evaluated: Cay1: Urochloa hybrid cv. Cayman (harvested after 65 days of regrowth: low quality); Cay2: cv. Cayman harvested after 45 days of regrowth; CayLl: cv. Cayman + Leucaena leucocephala; CayLd: cv. Cayman + Leucaena diversifolia; Hay: Dichantium aristatum hay as a comparator of common naturalized pasture. For each diet representing different levels of intensification (naturalized pasture, improved pasture, and silvopastoral systems), CH4 emissions were measured using the polytunnel technique with four zebu steers housed in individual chambers. The CH4 accumulated was monitored using an infrared multigas analyzer, and the voluntary forage intake of each animal was calculated. Dry matter intake (DMI, % of body weight) ranged between 0.77 and 2.94 among diets offered. Emissions of CH4 per kg of DMI were significantly higher (P < 0.0001) in Cay1 (60.4 g), compared to other treatments. Diets that included Leucaena forage legumes had generally higher crude protein contents and higher DMI. Cay1 and Hay which had low protein content and digestibility had a higher CH4 emission intensity (per unit live weight gain) compared to Cay2, CayLl and CayLd. Our results suggest that grass consumed after a regrowth period of 45 days results in lower CH4 emissions intensities compared to those observed following a regrowth period of 65 days. Diets with Leucaena inclusion showed advantages in nutrient intake that are reflected in greater live weight gains of cattle. Consequently, the intensity of the emissions generated in the legume-based systems were lower suggesting that they are a good option for achieving the emission reduction goals of sustainable tropical cattle production.

Investigation on daily or every three days supplementation with protein or protein and starch of cattle fed tropical forage

Effects of daily or every three days supplementation with protein or protein and starch on intake, digestion, rumen dynamics, urinary excretion characteristics, nitrogen (N) balance and, liver function of cattle fed high-quality tropical forage were evaluated. Five Nellore heifers (299 ± 7.5 kg of body weight) fitted with ruminal and abomasal cannulas were used in a 5 × 5 Latin square design. Treatments included: control; 200 g of crude protein (CP) daily; 200 g of CP and 400 g of starch daily; 600 g of CP every three days; 600 g of CP and 1,200 g of starch every three days. Supplements enhanced (P < 0.02) CP and digested organic matter intake. Among supplemented animals, every three days (infrequent) supplementation decreased (P < 0.05) forage intake. Supplements enhanced (P < 0.01) total organic matter and CP digestibility. Ruminal N balance was also enhanced (P < 0.01) by supplements, changing from negative in control to positive in supplemented animals. On average, supplements enhanced (P < 0.01) rumen ammonia nitrogen (RAN) compared to the control. However, an interaction (P < 0.01) between treatments and days pointed out that RAN levels were constant over days for control and frequently supplemented animals, but for infrequent supplemented animals it was greater on supplementation day and then decreased in the two following days. Supplements improved (P < 0.01) N balance, but without (P ≥ 0.43) differences among them. On average, supplemented animals presented greater (P < 0.01) urinary-N excretion (UNE) than control. Supplements, on average, also enhanced (P < 0.01) serum urea-N (SUN). Among supplemented animals, addition of starch to supplements reduced (P < 0.04) UNE, but it did not result in greater N retention. There was (P < 0.01) an interaction between days and treatments for SUN and the urinary excretion characteristics. Non-supplemented and daily supplemented animals presented constant values for these variables along the three-day-supplementation cycle. However, in animals supplemented every three days changes in SUN levels resulted in an untypical decoupling between SUN and RAN throughout the supplementation cycle. While RAN peaked on supplementation day, SUN peaked a day latter, which seem to be supported by a greater urea-N salvage in kidneys on day after supplementation. The changes in SUN and urinary excretion pointed out that the day after supplementation seem to be important for N salvage in ruminants infrequently supplemented. In summary, supplemented animals have greater N balance. Starch addition to protein supplements does not enhance N balance.

Effect of essential and vegetable oil blend supplementation on animal performance, feed intake, rumen fermentation and rumen microbial populations of crossbred steers finished in a pasture system

Recent years have seen a general increase in consumer concern regarding the profile of additives in animal feed and food sources, prompting the industry to study essential oil blends that have been promoted to replace synthetic products. This study evaluated the effect of essential oil blends supplementation on animal performance, feed intake, rumen fermentation and rumen microbial populations in crossbred steers finished in a pasture system. A total of 40 steers (½ Bons Mara vs. ½ Nellore) with a mean age of 20 ± 2.0 months and a mean body weight of 416.9 ± 5.56 kg were distributed in a completely randomized design with five diets and eight replications per diet. The five experimental diets were: CONT – basal diet, and oil blend inclusion in dosages of 1500, 3000, 4500 or 6000 mg/animal/d. Animal performance was similar among diets. The forage intake, crude protein, neutral detergent fiber, ethereal extract, non-fibrous carbohydrates, and the digestibility of crude protein, neutral detergent fiber, and non-fibrous carbohydrates were greater when essential oil blends were fed to steers. There was an increase in the concentrations of rumen ammonia nitrogen, and propionic and isovaleric volatile fatty acids when essential oil blends were used. The microbiological population of the rumen was similar among the five diets. Our results suggest that the inclusion of doses above 1500 mg/animal/ is high for livestock grazing on temperate pasture, further studies are needed to identify a promising dose to replace antimicrobial additives.

One in the Hand Worth Two in the Bush? Reproductive Effort of Young Males Is Not Affected by the Presence of Adult Males

Reproduction is a costly endeavor, and most large, long-lived, and iteroparous mammals exhibit conservative life-history tactics wherein an individual may forego or abandon a reproduction event for the sake of survival. Nevertheless, risks and benefits associated with reproduction are not equal across males and females, nor across their life. Whereas expenditure for females is associated with rearing young (e.g., lactation), expenditure for males occurs with securing mating opportunities. Young males may be more successful when dominant males are lacking, but it is less clear whether—and at what cost—young males will expend effort when those opportunities arise. We designed an experiment to quantify reproductive effort (e.g., food intake, somatic loss [body mass and fat]) of male white-tailed deer (Odocoileus virginianus) to better understand the reproductive ecology of male ungulates, with an emphasis on determining how adult males (≥4.5-years old) affect timing and extent of reproductive effort expended by yearling males (1.5-years old). Food intake, hormone levels, body mass, and somatic loss during rut were similar between yearling males that interacted with adult males and those that did not. Somatic loss by all males was greatest during peak estrus of females, but forage intake relative to metabolic body mass for yearling males was nearly twice that of adult males. Testosterone levels were lower for yearling than adult males early in rut and were related negatively to forage intake. Whereas adult males lost 20% (23.5kg) of body mass and 31% (5.3 percentage points [ppt]) of body fat during the rut, yearling males lost 12% (9.3kg) of body mass and 22% (4.7ppt) of body fat. Reproductive effort by young males was not influenced by the presence of adult males, though young males expended less reproductive effort than adults. Instead, reproductive allocation occurred in a state-dependent manner, where pre-season levels of somatic reserves dictated reproductive effort, regardless of age. Like female ungulates, male deer displayed risk-sensitive reproductive allocation wherein current reproductive allocation occurred as a function of resources garnered during the prior season and were expended in a way that should have avoided over-investing and creating a tradeoff between reproduction and survival.

Balanced protein/energy supplementation plan for beef cattle on tropical pasture

The objective of this study was to evaluate the effects of the amount of balanced protein/energy supplement adjusted according to the protein content of the pasture on intake, digestibility, and performance of young bulls managed on tropical pasture. Thirty-six crossbred bulls (½ Angus × ½ Nellore) averaging 8 months of age and 217.2 ± 4 kg were distributed to eight 1-hectare paddocks with tropical grass. The treatments were based on the amounts of balanced protein/energy supplement (0, 2.8, 5.5 and 7.4 g/kg of body weight - BW). The amounts of supplement were chosen to achieve dietary protein levels of 110, 130 and 150 g/kg of dry matter (DM). The increase of supplementation had a positive linear pattern (P < 0.05) on intakes of DM, crude protein (CP), organic matter (OM), digestible organic matter (DOM) and CP:DOM ratio. However, the intakes of forage and neutral detergent fiber (NDF) did not change (P > 0.05) with supplementation. The apparent digestibility of DM, OM, CP and NDF were not affected (P > 0.05) by increasing supplement amounts. Conversely, the grazing time decreased linearly (P = 0.022) with increasing supplementation. Moreover, a linear increase in the final body weight (P = 0.002) and average daily gain (P = 0.002) and, a linear decrease in the efficiency of supplement use (P = 0.021) were observed with increasing supplementation. Increasing the amount of balanced protein/energy supplementation increases the DM intake, digestibility and animal performance with no substitution effect on forage intake.

Effects of supplementation strategies for beef cattle in tropical grassland conditions

This study was realized to evaluate the dry matter intake, nutrient digestibilities, and animal performance of crossbred steers grazing Brachiaria brizantha cv. Marandu, during the rainy season. Thirty-three crossbred steers with an average weight of 203.5 ± 39.5 kg were distributed in a completely randomized design with three treatments and eleven replications. The results were analyzed using an ANOVA and a Tukey test with a 5% probability of error. The three experimental diets were: MSA – mineral salt ad libitum; MSU - mineral salt + urea ad libitum and PSU - protein supplementation (0.1% of body weight). The dry matter intake of forage and total dry matter intake were similar (P &gt; 0.05) among treatments. The dry matter, organic matter, neutral detergent fiber, crude protein, ether extract, non-fibrous carbohydrates and total carbohydrates digestibilitities coefficients were influenced (P &lt; 0.05) by treatments. The final body weight, average daily gain, and feed efficiency were similar (P &gt; 0.05) among treatments. The supplementation strategies used during the rainy season resulted in a similar performance; therefore, the strategy adopted could be chosen according to the economical and regional conditions of the production.

Whole-lactation feed intake, milk yield, and energy balance of Holstein and Swedish Red dairy cows fed grass-clover silage and 2 levels of byproduct-based concentrate

Ruminants can produce meat and milk from fibrous feed and byproducts not suitable for human consumption. However, high-yielding dairy cows are generally fed a high proportion of cereal grain and pulses, which could be consumed directly by humans. If high production of dairy cows could be maintained with ingredients of low human interest, the sustainability of dairy production would improve. In the present study, 37 multiparous [Holstein (n = 13) and Swedish Red (n = 24)] dairy cows were followed over a whole lactation. A low-concentrate diet of up to 6 kg concentrate per day (6kgConc) was fed to 27 cows, whereas 10 cows were fed a high-concentrate diet of up to 12 kg concentrate per day (12kgConc). The concentrate was mainly based on byproducts (sugar beet pulp, wheat bran, rapeseed meal, distiller's grain). Grass-clover silage of high digestibility was offered ad libitum. Over the whole lactation, cows on the 6kgConc diet had lower dry matter intake and higher forage intake than cows on the 12kgConc diet. Milk yield and energy balance were not influenced by dietary treatment. However, the cows on the 6kgConc diet numerically produced 2.4 kg less energy-corrected milk than cows on 12kgConc diet. The study lacked the statistical power to identify treatment effects on daily yield below 2.8 kg of milk due to low number of animals per treatment. Feed efficiency (as energy-corrected milk yield/dry matter intake or residual feed intake), body weight change, body condition change, milk fatty acid concentration in total milk fatty acids, plasma nonesterified fatty acids, glucose, β-hydroxybutyrate, and fertility measurements were not affected by diet, supporting the energy balance results. However, higher plasma concentrations of insulin-like growth factor-1 and insulin were observed in cows fed the 12kgConc diet. These findings show that cows can adapt to a high-forage diet virtually without human-grade ingredients, without compromising feed efficiency or energy balance, thereby contributing to sustainable food production.

Milk Production, N Partitioning, and Methane Emissions in Dairy Cows Grazing Mixed or Spatially Separated Simple and Diverse Pastures.

Simple SummaryIt is possible to increase performance of grazing dairy cows while decreasing their environmental impact through incorporating high-quality pasture species that synthesize high bioactive compounds in diverse pastures. In this study, cows grazed combination of simple pastures containing perennial ryegrass and white clover or diverse pastures containing forbs known to contain bioactive compounds that can reduce methane emissions and nitrate leaching soils. The two types of pastures were grown either as mixed or spatially separated in adjacent strips. Our study indicated that spatial separation had little impact on cows’ performance, but pastures containing diverse plant species improved the production of protein and lactose in milk and reduced environmental impact, specifically by improving nitrogen utilization of cows and reducing the emission of methane per amount of feed eaten by the cows.Increasing pasture diversity and spatially separated sowing arrangements can potentially increase the dry matter intake of high-quality forages leading to improved animal production. This study investigated the effects of simple (two-species) and diverse (six-species) pastures planted either in mixed or spatially separated adjacent pasture strips on performance, N partitioning, and methane emission of dairy cows. Thirty-six mid-lactation Jersey cows grazed either (1) simple mixed, (2) simple spatially separated, (3) diverse mixed, or (4) diverse spatially separated pastures planted in a complete randomized block design with three replicates. Compared to simple pasture, diverse pasture had lower CP content but higher condensed tannins and total phenolic compounds with an overall positive effect on yield of milk solids, nitrogen utilization, including a reduction of N output from urine, and methane yields per dry matter eaten. The spatial separation increased legume and CP content in simple pasture but decreased NDF in both diverse and simple pastures. In conclusion, increasing diversity using pasture species with higher nutritive value and secondary compounds can help improving the production while decreasing the environmental effect of dairy farming, while spatial separation had a minor effect on feed intake and yield, possibly due to overall high-quality pastures in early spring.

Feeding various forages and live yeast culture on weaned dairy calf intake, growth, nutrient digestibility, and ruminal fermentation

The objective of this study was to determine effects of various forages and live yeast culture on intake, growth, nutrient digestibility, and ruminal fermentation of weaned dairy calves. Holstein calves (n = 45) were randomly assigned to 2 × 3 factorial treatments: live yeast culture or no yeast and alfalfa haylage (AH), corn silage (CS), or grass hay (GH). Calves were weaned at 6 wk of age, housed individually, and studied from 7 to 16 wk of age. Rations, consisting of an 18% crude protein texturized grower (yeast or no yeast) and assigned forage, were offered as separate components until 9 wk of age. After 9 wk, diets were offered as a total mixed ration (TMR). Concentrate intake was capped at 2.25 kg of dry matter (DM)/d, and forage was offered ad libitum. The TMR contained equal forage neutral detergent fiber (8 ± 0.5%) on a DM basis for each basal diet. Calves were fed TMR to limit concentrate intake, and additional forage was offered ad libitum after 8 h if the entire TMR allotment was consumed. Total fecal collection (12 calves) was conducted for 4 d at 11 and 15 wk of age. Feeds and feces were evaluated for DM, neutral detergent fiber, acid detergent fiber, and starch to calculate digestibility. On the last day of fecal collection, rumen samples were collected to evaluate pH and volatile fatty acid (VFA) profile. Metabolizable energy and DM intake was least for calves consuming GH compared with other forages. Forage intake (% of DM intake) increased as calves aged (AH = 20 to 44.4%, CS = 24.5 to 37.6%, GH = 11.3 to 32.3% at 10 and 16 wk of age, respectively). Calves on CS had the greatest average daily gain and empty body weight gain, and calves on GH had the least. Calves on GH tended to have the lowest final body weight. There were no differences in structural growth. Digestibility of DM decreased with age. Fiber digestibility was least for calves on CS, and starch digestibility was least for calves on AH. Mean and minimum rumen pH increased with age. Forage offered changed VFA profile and there was an interaction between yeast and forage on VFA profile. These results indicated that recently weaned calves perform well on AH, CS, or GH and have minimal benefit from yeast supplementation. Feeding GH reduced weight gain, but all calves achieved a level of gain to meet growth goals for breeding and freshening. Furthermore, the ability to consume large portions of the ration as forage allows for more economical diets to be fed.

Methane and carbon dioxide emissions and grazed forage intake from pregnant beef heifers previously classified for residual feed intake under drylot conditions

The objectives of this study were to quantify the effect of post-weaning residual feed intake (RFI) on subsequent grazed forage intake, methane (CH4), and carbon dioxide (CO2) emissions. Beef heifers classified for RFI adjusted for off-test backfat (RFIfat; 55 high and 56 low) at 9 mo of age were monitored 7 mo later for CH4 and CO2 emissions using the GreenFeed Emissions Monitoring system. About 56 of these heifers were also monitored as high and low RFIfat groups using open-path Fourier-transform infrared spectroscopy (OP-FTIR). Heifers were dosed with 1 kg of C32-labelled pellets once daily for 15 d, with twice daily fecal sampling the last 8 d to determine individual grazed forage intake using the n-alkane method. Low RFIfat pregnant heifers consumed less forage (10.25 vs. 10.81 kg dry matter d−1; P &lt; 0.001), and emitted less daily CH4 (238.7 vs. 250.7 g d−1; P = 0.009) and CO2 (7578 vs. 8041 g d−1; P &lt; 0.001) compared with high RFIfat animals. Results from the OP-FTIR further confirmed that low RFIfat heifers emitted 6.3% less (g d−1; P = 0.006) CH4 compared with their high RFIfat cohorts. Thus, selection for low RFIfat will decrease daily CH4 and CO2 emissions from beef cattle.

Influence of stocking rate and advancing season on forage intake, digestibility, and ruminal fermentation in steers supplemented with dried distillers grains with solubles while grazing northern Great Plains rangelands.

The objectives of this study were to evaluate the effects of stocking rate and advancing season on diet chemical composition, intake, digestibility, and ruminal fermentation in steers supplemented with distillers grains with solubles [0.3% of body weight (BW)] while grazing northern Great Plains rangelands. Angus cross beef steers (n = 188; 320 ± 30.3 kg initial BW) were used to establish targeted stocking rates, and 12 ruminal cannulated steers (272 ± 20.0 kg initial BW) were used for diet sampling while cograzing with the noncannulated animals on 12 pastures (n = 3 per treatment). Stocking rates were set to target 65%, 50%, 35%, and 20% of an average annual above-ground biomass remaining at the end of the grazing season (May–September). Five 10-d collection periods were conducted for May 13–22, June 10–19, July 8–17, August 5–14, and September 2–11. There was no difference in steer BWs or average daily gain during any of the collection periods or between stocking rate (P ≥ 0.10). Organic matter (OM), neutral detergent fiber, and acid detergent fiber of forage masticate samples were not affected (P ≥ 0.25) by stocking rate. Crude protein, and all N fractions of forage masticates also did not differ between stocking rate treatments (P ≥ 0.18). Forage OM intake (grams per kilogram of BW) increased cubically across the entire grazing season (P = 0.05). Organic matter digestibility decreased quadratically (P < 0.01) from May to September. Neutral detergent fiber digestibility showed a cubic effect (P < 0.01) across the grazing season, increasing from May to June, then decreasing till September. Crude protein digestibility decreased linearly (P < 0.01) as the season advanced. Ruminal ammonia and volatile fatty acid (VFA) concentrations were affected by stocking rate × period interactions (P ≤ 0.02). Ruminal pH, ammonia, and VFA concentrations were not affected by the stocking rate (P > 0.13) but were impacted by the advancing season (P < 0.01). Ruminal pH increased quadratically (P ≤ 0.01) with advancing season (6.3 to 6.6 ± 0.05 from May to September, respectively). The results of this study demonstrate that intake, fermentation, and digestibility of northern Great Plains forages were influenced more by seasonal factors associated with forage maturity than stocking rate under the conditions of this study.