Growth performance, nutrient digestibility, blood parameters, and carcass characteristics by lambs fed an oregano and cobalt blend.

Shifting ruminal fermentation via feeding a blend of oregano (Organum vulgare L.) essential oils and Co-lactate (EOC; Rum-A-Fresh, Ralco, Inc. Marshall, MN) could improve lamb growth and carcass performance. Eighteen Suffolk × Little Han Tail F1 male lambs (20.3 ± 0.23 kg BW and approximately 3 months old) were randomly assigned using a completely random design to one of three treatments. Treatments were (1) EOC0: basal ration without EOC, (2) EOC4: basal ration plus 4 g/d EOC, and (3) EOC7: basal ration plus 7 g/d EOC. Initial and 24 d BW was similar (P > 0.10), but at 48 and 72 d, lambs fed EOC7 demonstrated greater (P = 0.01) BW compared with EOC0 fed lambs, while lambs fed EOC4 were intermediate and similar (P > 0.05). Average daily gains (ADGs) for 0-24 and 0-72 d were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while DM intake was similar (P > 0.10). Feed conversions for 0-24 d were improved (P < 0.02) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. However, 0-72-d feed conversions were greater (P < 0.01) for lambs fed EOC7 compared to lambs fed EOC0, with lambs fed EOC4 being intermediate and similar (P > 0.05). DM, NDF, and ADF digestibilities were similar (P > 0.10) among treatments, while CP digestibility was greater (P < 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Carcass weight and dressing percentages were improved (P < 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4. Head width was greater (P > 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4, while rump width was greater (P > 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Plasma triglyceride and cholesterol concentrations were lower (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while albumin, total serum protein, and glucose concentrations were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Feeding an EOC blend as an alternative antibiotic growth promoter at 4 and 7 g/d linearly improved lamb growth performance, feed conversions, frame growth, carcass weights, dressing percentages, and immunity.

Performance of dairy cows fed diets formulated at 2 starch concentrations with either canola meal or soybean meal as the protein supplement.

This study was designed to evaluate the effects of substituting corn grain with nonforage fiber sources in diets containing soybean meal (SBM) or canola meal (CM) as the primary protein source. Sixteen Holstein cows were assigned to a replicated 4 × 4 Latin square design with 4 periods of 28 d each. Treatments were arranged as a 2 × 2 factorial with 2 protein sources (SBM and CM) and 2 dietary starch concentrations (21 and 27% dry matter, DM). Diets were formulated to contain 16.5% CP, and the 21% starch diets were obtained by replacing corn grain with soybean hulls and beet pulp. Protein source × starch interactions were observed for DM intake (DMI), milk fat and protein concentrations, milk protein yield, milk urea nitrogen, and feed efficiency. Cows fed CM diets had a higher DMI when dietary starch concentration was 27% compared with 21%, but those cows had DMI similar to that of cows on SBM diets regardless of the starch concentration. Milk fat percentage was decreased in cows fed CM with 27% starch compared with cows fed CM with 21% starch and cows fed SBM with 27% starch. Milk protein percentage and yield and milk lactose percentage were least in cows fed CM with 21% starch compared with the other 3 diets, but feed efficiency was greater for cows fed CM with 21% starch. Milk urea nitrogen was least in cows fed CM with 27% starch compared with the other 3 diets. Cows fed diets with 27% starch produced 2.5 kg/d more milk and 1.9 kg/d more energy-corrected milk compared with cows fed 21% starch. Digestibility of DM and organic matter was higher in cows fed SBM diets than in cows on CM diets, and cows fed 27% starch showed greater DM and organic matter digestibility than cows on 21% starch. Digestibility of neutral detergent fiber and acid detergent fiber was greater in diets with SBM than in those with CM. Molar proportion of acetate was the lowest for cows fed CM with 21% starch compared with cows fed SBM with 21% starch, with the remaining cows fed being intermediate and similar. However, propionate was highest for cows fed CM with 21% starch than for cows fed SBM with 21% starch, but the remaining treatments were intermediate and similar. Isobutyrate was greater for cows fed CM with 21% starch, which resulted in the lowest acetate:propionate ratio compared with cows fed the remaining treatments. Overall, we confirmed that the interaction of protein with starch in CM diets can sustain similar cow performance as with the SBM diets. Those making decisions about starch concentration and protein source should consider feed price when SBM or CM and different starch levels are being formulated in diets for lactating dairy cows.

Short communication: Feeding a rumen-degradable amino acid affects plasma thyroxine and triiodothyronine concentrations.

Our previous published work demonstrated that feeding rumen-degradable valine to late-lactation dairy cows increased milk production compared with control-fed cows, with a response that was equivalent to that of recombinant bovine somatotropin. To further elucidate the response mechanism, we hypothesized that thyroxine (T4) and triiodothyronine (T3), which are important regulators of basal metabolism, may be involved. Previous short-term studies have demonstrated increased milk production when feeding iodinated casein. Eight multiparous Holstein dairy cows (255 ± 26.4 d in milk) were blocked by milk yield (34.1 ± 8.25 kg/d) and randomly assigned to 1 of 4 treatments using a replicated 4 × 4 Latin square design with 21-d periods (7 d for dietary adaptation and 14 d for data collection). Treatments were control (CON), a single injection of recombinant bovine somatotropin (rbST), and synthetic valine fed at 40 (V40) or 80 (V80) g/cow per day. Cows were fed a total mixed ration with a distillers dried grains carrier fed at 113.4 g/d containing no valine or added valine. Blood samples were collected twice during wk 2 and 3 of each period for T3 and T4 analysis. Concentrations of T4 (3.28, 3.90, 3.98, and 3.87 µg/dL for CON, rbST, V40, and V80, respectively) were increased for cows receiving rbST, V40, and V80 compared with CON cows. Concentrations of T3 (125.7, 140.7, 148.8, and 139.7 ng/dL) were increased for cows receiving rbST, V40, and V80 compared with CON cows, with cows receiving V40 having the highest T3 concentrations. In conclusion, feeding rumen-degradable valine increases plasma T4 and T3 concentrations, which would explain the mechanism leading to increased milk production.

Multi-criteria evaluation of dairy cattle feed resources and animal characteristics for nutritive and environmental impacts.

On-farm nutrition and management interventions to reduce enteric CH4 (eCH4) emission, the most abundant greenhouse gas from cattle, may also affect volatile solids and N excretion. The objective was to jointly quantify eCH4 emissions, digestible volatile solids (dVS) excretion and N excretion from dairy cattle, based on dietary variables and animal characteristics, and to evaluate relationships between these emissions and excreta. Univariate and Bayesian multivariate mixed-effects models fitted to 520 individual North American dairy cow records indicated dry matter (DM) intake and dietary ADF and CP to be the main predictors for production of eCH4 emissions and dVS and N excreta (g/day). Yields (g/kg DM intake) of eCH4 emissions and dVS and N excreta were best predicted by dietary ADF, dietary CP, milk yield and milk fat content. Intensities (g/kg fat- and protein-corrected milk) of eCH4, dVS and N excreta were best predicted by dietary ADF, dietary CP, days in milk and BW. A K-fold cross-validation indicated that eCH4 and urinary N variables had larger root mean square prediction error (RMSPE; % of observed mean) than dVS, fecal N and total N production (on average 24.3% and 26.5% v. 16.7%, 15.5% and 16.2%, respectively), whereas intensity variables had larger RMSPE than production and yields (29.4%, 14.7% and 14.6%, respectively). Univariate and multivariate equations performed relatively similar (18.8% v. 19.3% RMSPE). Mutual correlations indicated a trade-off for eCH4 v. dVS yield. The multivariate model indicated a trade-off between eCH4 and dVS v. total N production, yield and intensity induced by dietary CP content.

Symposium review: Uncertainties in enteric methane inventories, measurement techniques, and prediction models.

Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emission factors. There is also significant uncertainty associated with enteric CH4 measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF6) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH4 emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH4 emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH4 prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH4 emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH4 prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH4 emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.

Characterization of linoleic acid (C18:2) concentration in commercial corn silage and grain hybrids.

Corn silage and high-moisture corn grain are commonly recognized as risk factors for biohydrogenation-induced milk fat depression and may be due to the high concentration of linoleic acid (C18:2) in corn. Corn silage and corn grain have a low concentration of fatty acids (FA), but due to their high inclusion rate in diets they contribute substantially to unsaturated FA intake. The first objective of this study was to characterize the contribution of individual plant parts to total FA in whole-plant chopped corn. The second objective was to characterize the variation in FA profile in commercial silage and grain hybrids and evaluate the relationship between FA profile and other nutrients. To determine the location of FA in the corn plant, 4 stalks from 4 different commercial hybrids were separated into stalk, husk and shank, leaves, cob, and kernels. On a dry matter basis, 80.5% of total FA were in the kernels, 11.8% in the leaves, 5.1% in the stalk, 1.7% in the cob, and 1.0% in the husk and shank. More than 96% of the oleic acid (C18:1) and 92.5% of the C18:2 was in the kernels, whereas 71.0% of the linolenic acid (C18:3) was in the leaves. Next, the FA composition of fresh whole-plant chopped corn from 124 silage hybrids and grain from 72 grain hybrids was determined over 2 yr from test plots in Pennsylvania. Last, to extend the characterization, FA composition of whole-plant corn silage from 45 hybrids grown in test plots in South Dakota were characterized. In the fresh whole-plant chopped corn from PA test plots, C18:2 as a percentage of total FA averaged from 48.7% in 2013 (percentiles: 10th = 45.2, 90th = 52.2) and 48.0% in 2014 (percentiles: 10th = 44.1, 90th = 49.4). Concentration of C18:2 in corn grain averaged 57.5% in the 2013 (percentiles: 10th = 53.4, 90th = 60.8) and 56.1% in 2014 (percentiles: 10th = 53.5, 90th = 59.4). In the corn silage from South Dakota, the concentration of C18:2 as percentage of total FA averaged 45.4% (percentiles: 10th = 39.4, 90th = 50.2) and C18:2 concentration as a percent of dry matter averaged 1.1% (percentiles: 10th = 0.76, 90th = 1.41). An increase in the concentration of C18:2 was associated with a decrease in C18:3 in fresh whole-plant chopped corn and with a decrease in C18:1 in corn grain. Total FA and C18:2 (as a percentage of dry matter) were positively correlated with starch and negatively correlated with neutral detergent fiber in both fresh whole-plant chopped corn and corn silage samples, whereas no correlation with these traits was observed for C18:2 as a percentage of total FA. In conclusion, FA concentration and profile of corn silage reflects to a great extent the FA composition of kernels and the proportion of grain in the silage. The variation in C18:2 across hybrids provides the opportunity to develop selection programs to decrease C18:2 in corn silage and grain. Selection based on C18:2 concentration as a percent of total FA is preferred as this trait did not correlate with other nutritional properties.

Predicting manure volatile solid output of lactating dairy cows.

Organic matter (OM) in livestock manure consisting of biodegradable and nonbiodegradable fractions is known as volatile solids (VS). According to the Intergovernmental Panel on Climate Change (IPCC) Tier 2 guidelines, methane produced by stored manure is determined based on VS. However, only biodegradable OM generates methane production. Therefore, estimates of biodegradable VS (dVS; dVS = VS - lignin) would yield better estimates of methane emissions from manure. The objective of the study was to develop mathematical models for estimating VS and dVS outputs of lactating dairy cows. Dry matter intake, dietary nutrient contents, milk yield and composition, body weight, and days in milk were used as potential predictor variables. Multicollinearity, model simplicity, and random study effects were taken into account during model development that used 857 VS and dVS measurements made on individual cows (kg/cow per day) from 43 metabolic trials conducted at the USDA Energy and Metabolism laboratory in Beltsville, Maryland. The new models and the IPCC Tier 2 model were evaluated with an independent data set including 209 VS and dVS measurements (kg/cow per day) from 2 metabolic trials conducted at the University of California, Davis. Organic matter intake (kg/d) and dietary crude protein and neutral detergent fiber contents (% of dry matter) were significantly associated with VS. A new model including these variables fitted best to data. When evaluated with independent data, the new model had a root mean squared prediction error as a percentage of average observed value (RMSPE) of 12.5%. Mean and slope biases were negligible at <1% of total prediction bias. When energy digestibility of the diet was assumed to be 67%, the IPCC Tier 2 model had a RMSPE of 13.7% and a notable mean bias for VS to be overpredicted by 0.4 kg/cow per day. A separate model including OM intake as well as dietary crude protein and neutral detergent fiber contents as predictor variables fitted best to dVS data and performed well on independent data (RMSPE = 12.7%). The Cornell Net Carbohydrate and Protein System model relying on fat-corrected milk yield and body weight more successfully predicted dry matter intake (DMI; RMSPE = 14.1%) than the simplified (RMSPE = 16.9%) and comprehensive (RMSPE = 23.4%) models to predict DMI in IPCC Tier 2 methodology. New models and the IPCC Tier 2 model using DMI from the Cornell Net Carbohydrate and Protein System model predicted VS (RMSPE = 17.7-19.4%) and dVS (RMSPE = 20%) well with small systematic bias (<10% of total bias). The present study offers empirical models that can accurately predict VS and dVS of dairy cows using routinely available data in dairy farms and thereby assist in efficiently determining methane emissions from stored manure.

The effect of energy restriction on fatty acid profiles of longissimus dorsi and tissue adipose depots in sheep.

Sheep production systems in northwest China depend mostly on natural grasslands. Seasonal growth and maturity fluctuations can cause periodical restrictions in food quality and quantity. These fluctuations, in turn, result in variability in fat deposition and fatty acid profiles in different fat depots. Consequently, the study objective was to compare fat deposition, intramuscular fat (IMF) percentage and fatty acid profiles of the longissimus dorsi (LD), kidney fat (KF), tail fat (TF), and subcutaneous fat (SF) in lambs under ME restrictions similar to seasonal changes observed in the natural grasslands of northwest China. Nineteen male Dorper × Small Tailed Han lambs were assigned to 2 treatments, a control (CON) fed at 1.0 MJ / W × d and restricted (RES) by restricting ME sequentially every 30 d (0.56 MJ / W × d, 0.84 / W × d, 1.0 MJ / W × d, 0.84 MJ / W × d, 0.56 MJ / W × d, 0.28 MJ / W × d). All lambs were harvested at the end of the 180 d experimental period. Compared to CON fed lambs, restricting ME resulted in lesser IMF, fat deposition indexes ( < 0.05) except testicular and heart fat and greater ( < 0.05) SFA in LD, KF, and TF depots. The RES fed lambs had greater ( < 0.05) -3 PUFA, eicosatrienoic acid (C20:3n3), eicosapentaenoic acid (C20:5n3, EPA), and trans-linolelaidic acid (C18:2n6t) in LD muscle. The conjugated linoleic acids (CLA) content was greater in the SF depots of the CON fed lambs compared to the RES fed lambs. Fatty acid ratios (unsaturated fatty acid; USFA:SFA, MUFA:SFA, PUFA:SFA), and percentage USFA in RES fed lambs were lesser in muscle and adipose tissue compared to CON fed lambs ( < 0.05), except SF depots. In RES fed lambs, EFA were less ( < 0.05) in LD and KF depots and the ratios of functional fatty acids were lesser in LD and some adipose tissues ( < 0.05), including lesser n-6:n-3 in KF and SF ( < 0.05) depots, lesser USFA, SFA, MUFA, SFA in LD, KF, and TF ( < 0.05) depots, and lesser PUFA and SFA in LD and TF ( < 0.05) depots. Results from this research demonstrate that sequential energy restriction, as might be experience during seasonal forage quality and quantity changes in natural grasslands, result in lesser intramuscular fat with associated lesser quality, as well as, changes in fatty acid composition in different fat depots, which has implications for both meat quality and animal physiological functions.

Development of small intestinal enzyme activities and their relationship with some gut regulatory peptides in grazing sheep.

Growth depends on an animal's capacity to digest and assimilate ingested nutrients, and insufficient supply and impairment will constrain lamb growth. Eight groups of Alpine Finewool lambs were harvested on 0, 3, 7, 14, 21, 28, 42, and 56 d to measure pH and enzymatic activities in the duodenum, proximal jejunum, middle jejunum, distal jejunum, and ileum mucosa or digesta. From the duodenum to the ileum the pH of intestinal mucosa and digesta increased, whereas pH changed very little with age. The trypsin, chymotrypsin, lipase, lactase, and α-amylase activities observed at birth decreased by d 3, followed by a nonuniform enzymatic response in the small intestine. The trypsin activity increased from d 3 to peak, at d 21, followed by a decline. Chymotrypsin activity followed the same general trend but with smaller responses in activities. Trypsin demonstrated greater enzymatic activity than chymotrypsin at the same age. The lipase activity of small intestinal mucosa and digesta changed little with age. The lactase activity was high at birth, decreased by d 3, and then increased, followed by a decrease as lambs approached weaning. α-Amylase activity was similar in the small intestinal mucosa and digesta at birth but increased with age for the duodenum and proximal jejunum. Plasma concentrations of cholecystokinin (CCK), secretin, and gastrin were positively correlated ( < 0.05) with ileal mucosa lipase activity. Plasma concentration of CCK, secretin, gastrin, and gastric inhibitory polypeptide (GIP) were positively correlated ( < 0.05) with ileal mucosa lactase activity. Plasma concentration of pancreatic polypeptide (PP) was negatively correlated ( < 0.05) with lactase activity in the middle jejunum and ileal mucosa. Plasma concentrations of CCK, secretin, gastrin, and GIP were positively correlated ( < 0.05) with α-amylase activity in the ileal mucosa but negatively correlated ( < 0.05) with duodenum, prejejunum, and middle jejunum. Plasma PP concentrations were positively correlated ( < 0.01) with α-amylase activity of duodenum, middle jejunum, and postjejunum mucosa but not with the enzyme activity of postjejunum and ileal mucosa ( > 0.05). Small intestinal enzymatic activities exist and may be sufficient to enhance lamb growth via appropriate nutrient supplementation.

Evaluation of essential oils and prebiotics for newborn dairy calves.

A blend of essential oils (EO; carvacrol, caryophyllene, -cymene, cineole, terpinene, and thymol) and prebiotics (arabinogalactans; Stay Strong; Ralco, Inc., Marshall, MN) was designed to promote immunity and stimulate appetite to diminish health challenges and stresses experienced by newborn calves. It was hypothesized that calves supplemented with the medium dose (2.5 g/feeding) of the commercial EO would demonstrate the optimal response. The study objective was to determine the optimal feeding rate of EO when added to a milk replacer (MR) compared with feeding a control or a yeast cell wall additive (YCW). One hundred Holstein calves from a commercial dairy farm were blocked by birth date and randomly assigned to 1 of 5 treatments. Treatments were a control (CON), a 24:20% CP:fat (as-fed basis) MR (24:20 MR) without EO; EO mixed into the 24:20 MR at a rate of 1.25 g/feeding (EO-0.5), EO mixed into the 24:20 MR at a rate of 2.5 g/feeding (EO-1.0), or EO mixed into the 24:20 MR at a rate of 3.75 g/feeding (EO-1.5); or 24:20 MR with YCW mixed in at a rate of 2 g/calf at each feeding. The 24:20 MR was fed in a bucket 2 times/d at a rate of 0.28 kg/calf daily for 14 d, which was increased to 0.43 kg/calf at 2 times/d until d 35 and then reduced to 1 time/d at d 36 to facilitate weaning at d 42. Decoquinate was added to the MR at 41.6 mg/kg for coccidiosis control. Calves were housed in individual hutches bedded with straw with ad libitum access to a 20% CP pelleted calf starter and water. All data were analyzed using PROC MIXED as a completely random design. Calves fed EO-0.5 demonstrated greater ( < 0.05) ADG (0.65, 0.71, 0.64, 0.64, and 0.63 kg/d for the CON, EO-0.5, EO-1.0, EO-1.5, and YCW, respectively) through d 56 compared with calves fed EO-1.0 and YCW and tended ( < 0.10) to have greater ADG than calves fed the CON and EO-1.5. Total BW gains were greater ( < 0.05) for calves fed EO-0.5 compared with calves fed EO-1.0 and YCW, with calves fed the CON and EO-1.5 being intermediate and similar. Body length and wither height gains (final - initial) were greater ( < 0.05) for calves fed EO-0.5 compared with calves fed the other treatments. Hip width gains were similar ( < 0.10) among treatments. Hip height gains were increased ( < 0.05) for calves fed EO-0.5 compared with calves fed the CON, EO-1.0, EO-1.5, and YCW. These results demonstrate that supplementing EO-0.5 (1.25 g/calf daily) in a 24:20 MR may be the optimal feeding rate to enhance growth rates compared with feeding a 24:20 MR and a 24:20 MR containing YCW or other inclusion rates of EO.

Estimating the energetic cost of feeding excess dietary nitrogen to dairy cows.

Feeding N in excess of requirement could require the use of additional energy to metabolize excess protein, and to synthesize and excrete urea; however, the amount and fate of this energy is unknown. Little progress has been made on this topic in recent decades, so an extension of work published in 1970 was conducted to quantify the effect of excess N on ruminant energetics. In part 1 of this study, the results of previous work were replicated using a simple linear regression to estimate the effect of excess N on energy balance. In part 2, mixed model methodology and a larger data set were used to improve upon the previously reported linear regression methods. In part 3, heat production, retained energy, and milk energy replaced the composite energy balance variable previously proposed as the dependent variable to narrow the effect of excess N. In addition, rumen degradable and undegradable protein intakes were estimated using table values and included as covariates in part 3. Excess N had opposite and approximately equal effects on heat production (+4.1 to +7.6 kcal/g of excess N) and retained energy (-4.2 to -6.6 kcal/g of excess N) but had a larger negative effect on milk gross energy (-52 to -68 kcal/g of excess N). The results suggest that feeding excess N increases heat production, but more investigation is required to determine why excess N has such a large effect on milk gross energy production.

Evaluation of a high forage total mixed ration on the lactational performance of late lactation dairy cows.

Dairy producers continuously ask questions challenging the paradigm of how much forage can be included in the ration to meet the nutrient requirements of lactating dairy cows to support milk production. The production and feeding of forages having both high dry matter digestibility (DMD) and neutral detergent fiber digestibility (NDFd) are needed to increase nutrient supply. Mid- to late-lactation lactating Holstein dairy cows were blocked by parity (10 primiparous and 10 multiparous), milk production (range 33.9 to 56.6; µ = 41.5 kg/d), and days in milk (DIM) (range 140 to 287; µ = 225 d) and randomly assigned within blocks to 1 of 2 rations based on medium forage (MF) or high forage (HF) inclusion rates. A forage blend consisting of 60% second cutting (2012) alfalfa haylage and 40% (2012) corn silage blended on a DM basis and then fed at either 60% (MF) or 80% (HF) of the ration DM. The alfalfa haylage DM (DMD = 75.7%) and NDF (NDFd = 55.7%) digestibility was above average, but corn silage (DMD = 72.9, NDFd = 52.3%, and starch = 32.1%) was average. The experimental design was a randomized completed block design with 4 continuous weeks for data collection preceded by a 1 wk covariate data collection period in which all cows were fed the MF ration. Cows were milked 3 times/d and milk weights recorded at each milking and milk samples were collected at each milking once weekly for analysis of milk composition. Rations were similar in crude protein (CP; 16.4%), starch (20.1%), acid detergent fiber (ADF; 21.8%), and NDF (34.1%) concentrations. Covariately adjusted milk production (28.1 and 24.1 kg/d for MF and HF, respectively) and 4% fat-corrected milk (FCM; 27.6 and 24.1 kg/d) were significantly reduced by feeding the HF ration compared with cows fed the MF ration, while milk fat (3.98 and 4.0%), milk protein (3.11 and 3.17%), milk lactose (4.81 and 4.77%), and milk solids-not-fat (8.87 and 8.77%) percentages were similar for cows fed both rations. Cows on the HF ration demonstrated a significant reduction in DMI and a trend for decreased body weight (BW) when compared with cows fed the MF ration. The forage nutrient digestibility was not adequate to support the milk production of mid- to late-lactation dairy cows when fed at 80% of the DM. The forage nutrient digestibility when fed at very high inclusion rate (80%) could not meet the nutrient requirements of mid- to late-lactation dairy cows.

Developmental changes in fatty acid-binding protein (H-FABP) mRNA expression and intramuscular fat (IMF) content in Oula sheep.

Increasing meat consumption by Chinese people has created a focus for improving meat quality for increasing quality of life. Twenty-five Male Oula sheep were selected at 2, 21, 56, 84, and 112 d to investigate the developmental changes associated with age on the intramuscular fat (IMF) content of heart fatty acid-binding protein (H-FABP) mRNA expression in muscle. Longissimus dorsal muscle and biceps femoris muscle were sampled to measure IMF concentrations and total mRNA was extracted to measure H-FABP mRNA expression using real-time polymerase chain reaction (PCR). Growing male Oula sheep demonstrated that the IMF concentrations continuously increased with age and significant differences (P < 0.05) were detected among the age groups; 2. The IMF concentrations among tissues were different; 3. The development changes in H-FABP mRNA expression in longissimus dorsal muscle and biceps femoris muscle were similar with a decrease from 2 to 21 d, followed by continuously increasing concentrations being significant different (P < 0.05) among age groups; 4. The H-FABP mRNA expression in the longissimus dorsal muscle tissue was significantly (P < 0.05) higher compared to the biceps femoris muscle; 5. The muscle H-FABP mRNA expression concentration was positively correlated with IMF concentrations from d 21 to 112; 6. The correlation coefficients were significantly (P < 0.01)different between H-FABP gene mRNA expression in the longissimus dorsal muscle and IMF concentration of 0.815 compared to the biceps femoris muscle and IMF concentration of 0.787,which indicated that the H-FABP gene may be affecting the IMF concentrations in the early developmental stages of Oula sheep. These results support the hypothesis that H-FABP gene and its expression in muscle tissue is related to the IMF concentration of meat.

Effects of Saccharomyces cerevisiae fermentation products on the lactational performance of mid-lactation dairy cows.

This study was to evaluate 1 current and 2 newly developed Saccharomyces cerevisiae fermentation products (SCFP, Diamond V Original XPC and 2 test products) on the production efficiency of mid-lactation dairy cows. Eighty mid-lactation (164.5 ± 67.5 d in milk: DIM) Holstein cows (56 multiparous and 24 primiparous) were blocked by parity, DIM, and milk production, and randomly assigned to 1 of 4 treatments. Treatments consisted of: 1) Control (CON): corn silage and haylage based ration; 2) XPC: CON ration with Original XPC added at 14 g/d; 3) Product 1 (P1): CON ration with Product 1 added at 5 g/d; and 4) Product 2 (P2): CON ration with Product 2 added at 19 g/d. Treatments were blended with dried distillers grains and then mixed into a total mixed ration at 454 g/d. The first 14 d of the study (d-14 to 0) was for training cows to use the Calan door feeding system and cows were fed the CON ration during this period followed by an 8 wk continuous experimental period. Dry matter intakes were similar (P > 0.10) when cows were fed all treatments (25.7, 26.1, 25.1, and 26.2 kg/d for CON, XPC, P1, and P2, respectively). Milk production (33.3, 34.4, 35.5, and 36.8 kg/d) was improved (P < 0.05) for cows fed P2 compared to cows fed CON, with cows fed other treatments being intermediate and similar (P > 0.10). Feed efficiency (milk yield/dry matter intake) was improved (P < 0.05) for cows fed P1 and P2, compared to cows fed CON and XPC (1.30, 1.34, 1.49 and 1.41 kg/kg). Milk fat content was reduced (P < 0.05) for cows fed P2 (4.17, 3.93, 4.08, and 3.85%) compared to cows fed CON, with cows fed other treatments being intermediate (P > 0.10). Milk protein and lactose percentages were similar (P > 0.10) among treatments. Cows fed P2 had reduced (P < 0.05) molar proportion of ruminal acetate (63.8, 64.0, 63.1, and 62.3%) and greater (P < 0.05) propionate (18.9, 19.3, 19.7, and 20.6%) than cows fed other treatments. Supplementing a dairy ration with SCFP, such as P2, can improve milk production and feed efficiency of mid-lactation cows.

Single-dose infusion of sodium butyrate, but not lactose, increases plasma ß-hydroxybutyrate and insulin in lactating dairy cows.

Several studies have identified beneficial effects of butyrate on rumen development and intestinal health in preruminants. These encouraging findings led to further investigations related to butyrate supplementation in the mature ruminant. However, the effects of elevated butyrate concentrations on rumen metabolism have not been investigated, and consequently the maximum tolerable dosage rate of butyrate has not been established. Therefore, the first objective of this work was to evaluate the effect of a short-term increase in rumen butyrate concentration on key metabolic indicators. The second objective was to evaluate the source of butyrate, either directly dosed in the rumen or indirectly supplied via lactose fermentation in the rumen. Jugular catheters were inserted into 4 ruminally fistulated Holstein cows in a 4×4 Latin square with 3-d periods. On d 1 of each period, 1h after feeding, cows were ruminally dosed with 1 of 4 treatments: (1) 2L of water (CON), (2) 3.5g/kg of body weight (BW) of lactose (LAC), (3) 1g/kg of BW of butyrate (1GB), or (4) 2g/kg of BW of butyrate (2GB). Sodium butyrate was the source of butyrate, and NaCl was added to CON (1.34g/kg of BW), LAC (1.34g/kg of BW), and 1GB (0.67g/kg of BW) to provide equal amounts of sodium as the 2GB treatment. Serial plasma and rumen fluid samples were collected during d 1 of each period. Rumen fluid pH was greater in cows given the 1GB and 2GB treatments compared with the cows given the LAC treatment. Cows administered the 1GB and 2GB treatments had greater rumen butyrate concentrations compared with LAC. Those cows also had greater plasma butyrate concentrations compared with cows given the LAC treatment. Plasma ß-hydroxybutyrate was greater and insulin tended to be greater for butyrate treatments compared with LAC. No difference in insulin was found between the 1GB and 2GB treatments. Based on plasma and rumen metabolites, singly infusing 3.5g/kg of BW of lactose into the rumen is not as effective at providing a source of butyrate as compared with singly infusing 1 or 2g/kg of BW of butyrate into the rumen. Additionally, rumen pH, rumen butyrate, plasma ß-hydroxybutyrate, glucose, and plasma butyrate were less affected in cows administered the 1GB treatment than in cows given the 2GB treatment. This finding suggests that singly dosing 1g/kg of BW of butyrate could serve as the maximum tolerable concentration for future research.

Modeling the trade-off between diet costs and methane emissions: A goal programming approach.

Enteric methane emission is a major greenhouse gas from livestock production systems worldwide. Dietary manipulation may be an effective emission-reduction tool; however, the associated costs may preclude its use as a mitigation strategy. Several studies have identified dietary manipulation strategies for the mitigation of emissions, but studies examining the costs of reducing methane by manipulating diets are scarce. Furthermore, the trade-off between increase in dietary costs and reduction in methane emissions has only been determined for a limited number of production scenarios. The objective of this study was to develop an optimization framework for the joint minimization of dietary costs and methane emissions based on the identification of a set of feasible solutions for various levels of trade-off between emissions and costs. Such a set of solutions was created by the specification of a systematic grid of goal programming weights, enabling the decision maker to choose the solution that achieves the desired trade-off level. Moreover, the model enables the calculation of emission-mitigation costs imputing a trading value for methane emissions. Emission imputed costs can be used in emission-unit trading schemes, such as cap-and-trade policy designs. An application of the model using data from lactating cows from dairies in the California Central Valley is presented to illustrate the use of model-generated results in the identification of optimal diets when reducing emissions. The optimization framework is flexible and can be adapted to jointly minimize diet costs and other potential environmental impacts (e.g., nitrogen excretion). It is also flexible so that dietary costs, feed nutrient composition, and animal nutrient requirements can be altered to accommodate various production systems.

Multivariate and univariate analysis of energy balance data from lactating dairy cows.

The objectives of the study were to develop a multivariate framework for analyzing energy balance data from lactating cows and investigate potential changes in maintenance requirements and partial efficiencies of energy utilization by lactating cows over the years. The proposed model accounted for the fact that metabolizable energy intake, milk energy output, and tissue energy balance are random variables that interact mutually. The model was specified through structural equations implemented in a Bayesian framework. The structural equations, along with a model traditionally used to estimate energetic parameters, were fitted to a large database of indirect calorimetry records from lactating cows. Maintenance requirements and partial efficiencies for both models were similar to values reported in the literature. In particular, the estimated parameters (with 95% credible interval in parentheses) for the proposed model were: net energy requirement for maintenance equal to 0.36 (0.34, 0.38) MJ/kg of metabolic body weight·day; the efficiency of utilizing dietary energy for milk production and tissue gain were 0.63 (0.61, 0.64) and 0.70 (0.68, 0.72), respectively; the efficiency of utilizing body stores for milk production was 0.89 (0.87, 0.91). Furthermore, additional analyses were conducted for which energetic parameters were allowed to depend on the decade in which studies were conducted. These models investigated potential changes in maintenance requirements and partial efficiencies over the years. Canonical correlation analysis was used to investigate the association between changes in energetic parameters with additional dietary and animal characteristics available in the database. For both models, net energy requirement for maintenance and the efficiency of utilizing dietary energy for milk production and tissue gain increased in the more recent decades, whereas the efficiency of utilizing body stores for milk production remained unchanged. The increase in maintenance requirements in modern milk production systems is consistent with the literature that describes increased fasting heat production in cows of higher genetic merit. The increase in utilization of dietary energy for milk production and tissue gain was partially attributed to the changes in dietary composition, in particular to the increase in dietary ether extract to levels closer to currently observed in modern milk production systems. Therefore, the estimated energetic parameters from this study can be used to update maintenance requirements and partial efficiencies of energy utilization in North American feeding systems for lactating cows.

Predicting nitrogen excretion from cattle.

Manure nitrogen (N) from cattle production facilities can lead to negative environmental effects, such as contribution to greenhouse gas emissions, leaching and runoff to aqueous ecosystems leading to eutrophication, and acid rain. To mitigate these effects and to improve the efficiency of N use, accurate prediction of N excretion and secretions are required. A genetic algorithm was implemented to select models to predict fecal, urinary, and total manure N excretions, and milk N secretions from 3 classes of animals: lactating dairy cows, heifers and dry cows, and steers. Two tiers of model classes were developed for each category of animals based on model input requirements. A total of 6 models for heifers and dry cows and steers and an additional 2 models for lactating dairy cattle were developed. Evaluation of the models using K-fold cross validation based on all data and using the most recent 6 yr of data showed better prediction for total manure N and fecal N compared with urinary N excretion, which was the most variable response in the database. Compared with extant models from the literature, the models developed in this study resulted in a significant improvement in prediction error for fecal and urinary N excretions from lactating cows. For total manure production by lactating cows, extant and new models were comparable in their prediction ability. Both proposed and extant models performed better than the prediction methods used by the US Environmental Protection Agency for the national inventory of greenhouse gases. Therefore, the proposed models are recommended for use in estimation of manure N from various classes of animals.

Quantifying body water kinetics and fecal and urinary water output from lactating Holstein dairy cows.

Reliable estimates of fresh manure water output from dairy cows help to improve storage design, enhance efficiency of land application, quantify the water footprint, and predict nutrient transformations during manure storage. The objective of the study was to construct a mechanistic, dynamic, and deterministic mathematical model to quantify urinary and fecal water outputs (kg/d) from individual lactating dairy cows. The model contained 4 body water pools: reticulorumen (QRR), post-reticulorumen (QPR), extracellular (QEC), and intracellular (QIC). Dry matter (DM) intake, dietary forage, DM, crude protein, acid detergent fiber and ash contents, milk yield, and milk fat and protein contents, days in milk, and body weight were input variables to the model. A set of linear equations was constructed to determine drinking, feed, and saliva water inputs to QRR and fractional water passage from QRR to QPR. Water transfer via the rumen wall was subjected to changes in QEC and total water input to QRR. Post-reticulorumen water passage was adjusted for DM intake. Metabolic water production and respiratory cutaneous water losses were estimated with functions of heat production in the model. Water loss in urine was driven by absorbed N left after being removed via milk. Model parameters were estimated simultaneously using observed fecal and urinary water output data from lactating Holstein cows (n=670). The model was evaluated with data that were not used for model development and optimization (n=377). The observations in both data sets were related to thermoneutral conditions. The model predicted drinking water intake, fecal, urinary, and total fresh manure water output with root mean square prediction errors as a percentage of average values of 18.1, 15.6, 30.6, and 14.6%, respectively. In all cases, >97% of the prediction error was due to random variability of data. The model can also be used to determine saliva production, heat and metabolic water production, respiratory cutaneous water losses, and size of major body water pools in lactating Holstein cows under thermoneutral conditions.

Manure nutrient excretion by Jersey and Holstein cows.

The objective of this study was to evaluate feces, urine, and N excretion by Jersey and Holstein cows. Sixteen multiparous cows (n=8 per breed) were fed 2 experimental rations at calving in a switchback experimental design. Diets were 50% forage and based on corn meal (control) or whole cottonseed. Half the cows in each breed started on the control diet and half started on the whole cottonseed diet. Cows were switched to the other diet at 60 d in milk and switched back to their original diet at 165 d in milk. Pairs of cows were moved into open-circuit respiration chambers on d 49, 154, and 271 of lactation for 7-d measurement periods. While in the chambers, total collection of feed refusals, milk, recovered hair, feces, and urine was conducted. No effect of the interaction of diet and breed was observed for measures of nutrient digestibility and manure excretion. Total daily manure excretion was lower in Jersey cows than in Holstein cows, with reductions generally proportional to changes in feed intake. Jersey cows consumed 29% less feed and excreted 33% less wet feces and 28% less urine than Holstein cows. Intake, fecal, and urinary N were reduced by 29, 33, and 24%, respectively, in Jersey cows compared with Holstein cows. Equations from American Society of Agricultural and Biological Engineers underpredicted observed values for all manure measures evaluated (urine, manure solids, N, wet manure), and breed bias was observed in equations predicting excretion of urine, N, and wet manure. Although these equations include animal and dietary factors, intercepts of regression of observed values on predicted values differed between Holsteins and Jerseys for those 3 measures. No breed bias was observed in the prediction of manure solids excretion, however, making that equation equally appropriate for Jerseys and Holsteins. The effect of breed on manure and nutrient excretion has significant nutrient management implications.