Altered rumen fermentation patterns in lactating dairy cows supplemented with phytochemicals improve milk production and efficiency.

Tannins and other phytochemicals are known to improve RUP in the diet by binding protein and then limiting ruminal degradation, which may improve milk yield and milk protein synthesis. The objective of this study was to evaluate the effects of dietary phytochemicals (tannins and Capsicum species) as rumen modifiers on production parameters and milk efficiency in dairy cows. Twenty-four multiparous Holstein cows (96 ± 16 d in milk; mean ± standard deviation) were used in a replicated 3 × 3 Latin square design balanced to measure carryover effects. Cows were blocked according to days in milk, milk production, and body weight and randomly assigned to 1 of 3 groups (n = 8/group). Each group was assigned to a unique treatment sequence across the 3 periods in the Latin square. The experiment consisted of a 14-d covariate period and three 30-d treatment periods. Cows received a basal diet supplemented with soybean meal pellets (SB) as the control diet, phytochemicals (RUM; Rumiviv, CCPA, Janzé, France) pelleted with soybean meal, or expeller soybean meal (ESBM; SoyPlus, West Central Soy, Ralston, IA). Milk production and dry matter intake during the last 4 d of each period were used for statistical analysis. Blood and rumen fluid samples were collected on d 27 of each period. Rumen fluid was analyzed for ammonia N and volatile fatty acids as well as ruminal bacteria via quantitative PCR amplification of 16S ribosomal DNA genes. Greater milk yield (37.9 vs. 36 kg/d), energy-corrected milk (39.7 vs 37.1 kg/d), and protein yield (1.15 vs. 1.08 kg/d) were observed in RUM compared with SB, but these parameters were similar between RUM and ESBM. Concentrations of total volatile fatty acids (118.1 vs. 101.5 mM) were greater in RUM in comparison to SB and ESBM diets. Cows fed RUM had greater ß-hydroxybutyrate (0.49 vs. 0.42 mmol/L) than SB and ESBM. Selenomonas ruminantium, Succinimonas amylolytica, and Streptococcus bovis in rumen fluid were lower in RUM fed cows in comparison to SB and ESBM. Increased total volatile fatty acids and lower ruminal abundance of bacteria associated with low feed efficiency in RUM cows can partially explain the improvements observed in milk yield and milk efficiency. Overall, these data suggest that feeding a combination of tannin mixture and Capsicum can significantly affect rumen fermentation characteristics via partial manipulation of rumen microbiota, and these effects were reflected in improved milk production and efficiency.

Technical note: A novel approach to estimate dry matter intake of lactating dairy cows through multiple on-cow accelerometers.

The objective of this study was to evaluate the feasibility of using multiple 3-dimensional accelerometers to estimated individual dry matter intake (DMI) of lactating dairy cows. Twenty-four Holstein cows in late lactation were assigned into 2 groups, a calibration group (n = 12) and a validation group (n = 12). All cows were fitted with 3 sensors that recorded 3-dimensional acceleration (i.e., x, y, and z) at 10-s intervals, 1 on the lateral side of the left hind leg and 2 attached directly to a halter over the nose and jaw area on the left side. Then, 3 accelerations were generated from each accelerometer (e.g., Leg-X, Leg-Y, and Leg-Z). Six new variables were created based on the change in acceleration in the nose and jaw accelerometers between 2 consecutive time points (e.g., LagJaw-X). For both groups (i.e., calibration and validation), cows were continuously video recorded while data on acceleration and intake of total mixed ration were collected for 10 consecutive days. Cows were fed once daily using an individual gate system, and individual refusals were recorded next day before morning feeding. Cows were fed a common lactating cow diet (17.9% crude protein; 1.70 Mcal/kg of dry matter). In the calibration group, individual eating bouts were obtained based on video recordings and merged with the corresponding accelerometer data. Then, a stepwise regression analysis was conducted using the REG procedure of SAS (SAS Institute, Cary, NC) to determine the ranges in acceleration that accounted for the highest variation in DMI (highest R2) in each acceleration variable. All 32,767 potential acceleration combinations were tested in the validation group using the acceleration ranges predetermined in the calibration group. The CORR procedure of SAS was used to test the Pearson correlation coefficient (r) between the type of DMI [i.e., based on accelerations (DMIaccel) or actual DMI (DMIactual)]. The MIXED procedure of SAS was used to perform a repeated-measures analysis with type (DMIaccel vs. DMIactual), day, and their interaction (T × D) in the model. From this analysis, 8 candidate acceleration models were selected based on high r and similarity (P > 0.15) in terms of T and T × D between DMIaccel and DMIactual. A simulated effect on DMIactual was artificially created in the validation group by dividing this group (n = 12) into high and low intake cows (n = 6/group; DMI of 24.1 vs. 18.7 kg/d), and the candidate models were tested to determine whether they were sensitive enough to detect this effect. From these candidate models, AEN (Leg-X + Jaw-Z + LagJaw-Z) showed a weak correlation (r = 0.36) between DMIaccel and DMIactual, but DMIaccel and DMIactual were highly similar (21.2 vs. 21.4 kg/d of DMI). In addition, this was the only model that could detect the simulated effect on DMIactual (22.1 vs. 20.3 kg/d of DMI) in the validation group. The fact that the simulated effect on DMIactual was detected based only on accelerations is highly significant, and models such as AEN could be substantially improved if they were derived from a greater sample size and included different physiological stages in dairy cows.

Limits of grape byproduct inclusion in diets for lambs: Zinc supplementation to prevent copper poisoning.

The aims of the current study were to assess the inclusion levels of grape byproduct replacing jiggs hay in lambs diets and to evaluate signs of copper poisoning. Thirty-four Texel and Corriedale crossbred female lambs were used in a randomized block experimental design. The treatments comprised four levels of grape byproduct (0; 100; 200 and 300 g/kg DM) in replacement of jiggs hay. The diets were adjusted to the same ZnCu ratio (6:1) of the basal diet. Grape byproduct consumption at up to 30%, led to similar weight gain in the different treatments (P = .92), which was suitable for growing lambs. Grape byproduct in the diet had linear effect on GGT (P < .001) and AST (P < .0001) enzymes as well as on total bilirubin (P = .05). In addition, the highest grape byproduct addition showed the highest consumption of hay (P < .01). Hay replacement by grape byproduct at up to 300 g/kg in the DM was satisfactory to weight gain and did not negatively affect feed intake and weight gain of growing lambs. Maintaining zinc:copper ratio in sheep diets is not effective in preventing liver damage caused by increased dietary copper concentrations over a period of 70 days.