Benzoic acid supplementation improves the growth performance, nutrient digestibility and nitrogen metabolism of weaned lambs

Nitrogen is one of the essential components of proteins and nucleic acids and plays a crucial role in the growth and development of ruminants. However, the nitrogen utilization rate of ruminants is lower than that of monogastric animals, which not only reduces protein conversion and utilization, but also increases manure nitrogen discharge as well as causing environmental pollution. The lamb stage is an important period in the life of sheep, which can affect the production performance and meat quality of fattening sheep. The purpose of this experiment was to explore effects of benzoic acid supplementation on growth performance, nutrient digestibility, nitrogen metabolism and plasma parameters of weaned lambs. A total of 40 weaned male Hu sheep lambs with similar body weight were randomly divided into 4 groups: control with no benzoic acid (0 BA) and the lambs in other 3 groups were fed 0.5, 1, and 1.5% benzoic acid on the basis of experimental diet (0.5, 1, and 1.5 BA, respectively). The experiment lasted for 60 days. Results showed that the average daily gain of 1 BA group was significantly increased (p < 0.05) when compared to 0 and 1.5 BA groups, while an opposite tendency of dry matter intake to average daily gain ratio was observed. The dry matter, organic matter, neutral detergent fiber and acid detergent fiber digestibility of 1 BA group was significantly increased (p < 0.05) as compared with 0 and 1.5 BA groups as well as plasma albumin content. Also, the urinary hippuric acid and hippurate nitrogen concentrations in 1 and 1.5 BA groups were higher (p < 0.05) than those in 0 and 0.5 BA groups. Additionally, the nitrogen intake in 0.5 and 1 BA groups was significantly increased (p < 0.05) when compared to other groups. At 1 h after morning feeding, the plasma benzoic acid concentration of 1 BA group reached up to maximum value and was higher (p < 0.05) than other groups, and then began to decrease. Similarly, the hippuric acid concentration in plasma of 1 and 1.5 BA groups was higher (p < 0.05) than that of 0 BA group from 1 to 4 h post morning feeding. At 3 h after feeding, the urea nitrogen concentration in plasma of 0 BA group was higher (p < 0.05) than that of 1.5 BA group. Overall, the appropriate supplementation of benzoic acid (1%) in the diet can improve growth performance and nitrogen metabolism of weaned lambs.

Average Daily Gain in Lambs Weaned at 60 Days of Age Is Correlated with Rumen and Rectum Microbiota

Colonization of gastrointestinal microbiota in mammals during early life is vital to host health. The objective of this study was to investigate whether lambs with high and low ADG have a different rumen and rectum microbial community. Thus, we investigated potential relationships between rumen and rectum microbiota and average daily gain (ADG) in weaned lambs. Sixteen lambs with similar body weights (7.63 ± 1.18 kg) were selected at 30 days of age. At 60 days of age, lambs were weaned, and ADG was calculated from 60 to 90 days. Then, two groups were generated: higher ADG (HG, 134.17 ± 13.48 g/day) and lower ADG (LG, 47.50 ± 19.51 g/day). Microbiota was evaluated at 30, 60, and 90 days of age. The final live weight and ADG at 90 days of age was higher (p < 0.05) in the HG group compared to the LG group. The maturity of bacterial and fungal communities was increased (p < 0.05) in the HG group for the 30 days vs. 90 days comparison and 60 days vs. 90 days comparison. Linear discriminant analysis effect size (LEfSe) analysis revealed a total of 18 bacterial biomarkers that are ADG-specific in the rumen and 35 bacterial biomarkers in the rectum. Meanwhile, 15 fungal biomarkers were found in the rumen and 8 biomarkers were found in the rectum. Our findings indicated that ADG is related to the rumen and rectum microbiota in lambs.

Effects of Dietary Supplementation with Glycerol Monolaurate (GML) or the Combination of GML and Tributyrin on Growth Performance and Rumen Microbiome of Weaned Lambs

Our objective was to evaluate the effects of dietary supplementation with glycerol monolaurate (GML) or the combination (Solider, SOL) of GML and tributyrin (TB) on the growth performance and rumen microbiome of weaned lambs. Thirty-six male Hu lambs (11.46 ± 0.88 kg BW and 40 ± 5 days of age) were divided into three treatment groups: (1) CON: basal diet, (2) GML: basal diet supplemented with GML at 1.84 g/kg DM, and (3) SOL: basal diet supplemented with SOL at 3 g/kg DM. GML increased the final BW (p = 0.04) and ADG (p = 0.02) compared with CON. There were no significant differences in the DMI (p > 0.10) among the three treatment groups. GML and SOL tended to decrease the dry matter intake/average daily gain (p = 0.07) compared with CON. GML tended to increase the apparent digestibility of CP (p = 0.08) compared with CON. SOL increased the apparent digestibility of NDF (p = 0.04) compared with CON. The Chao1 and Shannon indexes of SOL were both significantly higher than those of the other groups (p = 0.01). LefSE analysis showed that Bifidobacteriaceae of the Bifidobacteriales was enriched in the GML group. In addition, compared with GML, SOL reduced the relative abundance of Actinobacteria (p < 0.01) and increased the relative abundance of Verrucomicrobia (p = 0.05), and GML reduced the relative abundance of Ruminococcus (p = 0.03). Our results indicated that dietary supplementation with GML or SOL improved growth performance and feed conversion, and changed the rumen microbiome of weaned lambs.