Effects of dietary supplementation of peanut skins (Arachis hypogaea) on performance, digestibility, and rumen fermentation of cattle: a meta-analysis.

This study aimed to estimate the magnitude of the effects of dietary inclusion of peanut skins (PS) byproduct (Arachis hypogea L.) on intake, total-tract digestibility, and rumen fermentation of cattle via meta-analysis. Data were collected following the PRISMA methodology. Nine manuscripts and a graduate thesis met the inclusion criteria from 1983 to 2010. The effect size was estimated by calculating the weighted raw mean differences (RMD) between PS vs. control diets. The RMD was compared with a robust variance estimation method followed by a meta-regression and a dose-response analysis fitting the diet characteristics like crude protein content (CP), NDF content, ether extract content (EE), tannin content, and PS level in diet (0 to 40%) as covariates. Dietary PS decreased (P < 0.01) total-tract CP digestibility (52.0 vs. 64.3%), final body weight (371.5 vs. 397.9 kg), and average daily gain (1.14 vs. 1.44 kg/day) among treatment comparisons. Likewise, PS decreased total VFA (92.6 vs. 107.6 mmol/L) and NH3-N (8.22 vs. 12.1 mg/dL), but no effects were observed on rumen pH (6.47 vs. 6.14) and VFA molar proportions. Despite the between-cluster variance, dietary PS increased the ether extract digestibility (77.5 vs. 70.2%) among treatment comparisons. The subset and dose-response analysis revealed that PS should not exceed 8% (DM basis) in the diet to prevent negative effects on CP digestibility and animal performance. In conclusion, the results of this meta-analysis do not support the dietary inclusion of PS in cattle diets beyond 8%.

Effects of a xylanase-rich enzyme on intake, milk production, and digestibility of dairy cows fed a diet containing a high proportion of bermudagrass silage.

We previously reported that milk production in dairy cows was increased by adding a specific xylanase-rich exogenous fibrolytic enzyme (XYL) to a total mixed ration (TMR) containing 10% bermudagrass silage (BMD). Two follow-up experiments were conducted to examine whether adding XYL would increase the performance of dairy cows consuming a TMR containing a higher (20%) proportion of BMD (Experiment 1) and to evaluate the effects of XYL on in vitro fermentation and degradability of the corn silage, BMD, and TMR (Experiment 2). In Experiment 1, 40 lactating Holstein cows in early lactation (16 multiparous and 24 primiparous; 21 ± 3 d in milk; 589 ± 73 kg of body weight) were blocked by milk yield and parity and randomly assigned to the Control and XYL treatments. The TMR contained 20% BMD, 25% corn silage, 8% wet brewer's grain, and 47% concentrate mixture in the dry matter (DM). Cows were fed the XYL-treated or untreated experimental TMR twice per day for 10 wk after a 9-d covariate period. In Experiment 2, ruminal fluid was collected from 3 cannulated lactating Holstein cows fed a diet containing 20% bermudagrass haylage, 25% corn silage and 55% concentrate. In Experiment 1, compared with Control, application of XYL did not affect DM intake (24.0 vs. 23.7 kg/d), milk yield (35.1 vs. 36.2 kg/d), fat-corrected milk yield (36.1 vs. 36.9 kg/d), or yields of milk fat (1.29 vs. 1.31 kg/d) or protein (1.07 vs. 1.08 kg/d). However, intake of neutral detergent fiber (4.67 vs. 4.41 kg/d) tended to increase with XYL; consequently, milk protein concentration was increased by XYL (3.02 vs. 2.95%). Feed efficiency tended to be lower in cows fed XYL (1.57 vs. 1.52 kg of fat-corrected milk/kg of DM intake) compared with Control. In Experiment 2, XYL tended to increase the rate of gas production in the TMR, the molar proportion of propionate for corn silage, and that of valerate for the TMR. In addition, XYL increased in vitro DM, neutral detergent fiber, and acid detergent fiber degradability of BMD and corn silage. Application of XYL to a diet with a relatively high proportion of BMD tended to increase digestible neutral detergent fiber intake, increased milk protein concentration, and in vitro degradability of DM, neutral detergent fiber, and acid detergent fiber. However, XYL did not affect milk production and tended to decrease feed efficiency in early lactation cows.

Effect of Ovar-DRA and Ovar-DRB1 genotype in small ruminants with haemonchosis.

The effect of Ovar-DRA and Ovar-DRB1 genotypes on faecal egg count (FEC) was determined in sheep and goats infected with Haemonchus contortus. One hundred and forty-three sheep from 3 different breeds (St. Croix, Katahdin and Dorper) and 150 goats from three different breeds (Spanish, Boer and Kiko) were used. Parasitological (FEC), haematological (packed cell volume) and immunological (IgA, IgG and IgM) parameters were measured. Sheep populations showed a higher FEC and humoural response than goat breeds. Genotypes were determined by high-resolution melting assays and by conventional PCR. For Ovar-DRA, sheep and goats carrying the AA genotype showed significant lower FEC than AG and GG genotypes. The additive effect was found to be 115.35 less eggs per gram of faeces for the A allele for goats. For Ovar-DRB1, only in sheep, the GC genotype was associated with low FEC. The additive effect was 316.48 less eggs per gram of faeces for the G allele, and the dominance effect was 538.70 less eggs per gram of faeces. The results indicate that single nucleotide polymorphisms within Ovar-DRA and Ovar-DRB1 could be potential markers to be used in selection programmes for improving resistance to Haemonchus contortus infection.

Relative expression analysis of IL-5 and IL-6 genes in tropical sheep breed Pelibuey infected with Haemonchus contortus.

Haemonchus contortus is a parasitic nematode of Pelibuey sheep, a meat breed used in tropical regions. Due to anthelmintic problems, the identification of hosts resistant to H. contortus is another option of control. The aim of this study was to analyse the relative expression of IL-5 and IL-6 genes in Pelibuey sheep after H. contortus infection. Nineteen lambs infected with H. contortus and three more lambs without infection were studied. The haemonchosis was determined by the number of eggs per gram of faeces (epg) and by the estimation of the percentage of the packed cell volume (%pcv). Peripheral blood mononuclear cells (PBMCs) were obtained to extract RNA at 0, 1, 2, 7, 14, 21 and 28 days after infection to quantify the relative expression of IL-5, IL-6 and GAPDH by real-time PCR. Five lambs were classified as low responders (lr) to haemonchosis with averages of 1519 ± 315·3 epg and 31·49 ± 5·13%pcv, and 14 lambs were identified as high responders (hr) with averages of 530 ± 132 epg and 34·88 ± 3·75%pcv. The expression ratio of IL-5 was significantly different compared with control lambs at 2, 7 and 14 days post-infection (PI), and IL-6 was significantly different after 14 days. The highest level of relative expression for IL-5 and IL-6 genes was 9·9-fold and 12-fold after 2 and 14 days for hr hosts (P < 0·05) compared with control group, respectively. In conclusion, the Pelibuey breed in grazing areas exhibited different expression of IL-5 and IL-6 obtained from PBMCs against H. contortus, suggesting the importance of these cytokines in regulating the nematode infection.