TMAO: Trimethylamine-N-Oxide or Time to Minimize Intake of Animal Products?

Growth Performance, Blood Metabolites, Carcass Characteristics and Meat Quality of Lambs Fed Diets Containing Different Energy Levels Supplemented with Rumen-Protected Choline

This study aimed to examine the effects of metabolizable energy (ME) level and rumen-protected choline (RPC) supplementation on the growth performance, carcass characteristics, meat quality, serum energy, lipid, and protein profiles of Karayaka lambs. Twenty-eight Karayaka lambs, with an initial body weight (BW) of 26.85 ± 0.26 kg, were randomly assigned (2 × 2 factorial design) to one of four dietary treatments with two levels of ME (optimum: 2750 or low: 2500 kcal ME/kg dry matter) and two levels of RPC (0 or 4 g/d/lamb). Lambs of each group were housed in individual pens. The experiment lasted 66 d, with the first 10 d consisting of acclimation and the next 56 d of the formal experimental period. The data on BW, dietary matter intake (DMI), and serum glucose concentrations confirm that our model successfully induced low energy using 250 kcal/kg less energy than the optimum level. RPC supplementation did not significantly affect average daily DMI, total average daily gain (ADG), or feed conversion ratio (FCR) at any energy level. Additionally, there was no substantial effect on carcass characteristics, meat quality, serum lipids, energy metabolism indicators, and liver function parameters. There was also no interaction effect of RPC × ME on the parameters tested. However, at 56 d into the experiment, the interaction effect of RPC × ME on serum urea-N was highly significant, and RPC supplementation led to lower serum urea-N levels (p = 0.001). These results suggest that while RPC supplementation did not enhance overall performance and carcass characteristics in Karayaka lambs, it may play a role in modulating nitrogen metabolism, as indicated by the significant reduction in serum urea-N levels.

Supplementation of graded levels of rumen-protected choline to a pelleted total mixed ration did not improve the growth and slaughter performance of fattening lambs

Choline is an essential nutrient in ruminant diets, which contributes to the fundamental biological functions of the animal. However, choline is easily degraded in the rumen before it can be absorbed. Rumen-protected choline (RPC) supplementation might support the fast growth of ruminants. This study aimed to investigate the effects of supplementing graded levels of RPC in a pelleted total mixed ration for fattening lambs. Sixty three-month-old male Small Tail Han and northeast fine wool sheep hybrid lambs with a liveweight of 15.3 ± 1.8 kg (mean ± SD) were fed designated diets and randomly assigned into five treatment groups (n = 12 per group). The five treatments were the rate of RPC supplementation at 0, 1.25, 2.50, 3.75, and 5.00 g (equivalent to 0, 0.31, 0.63, 0.94, and 1.25 g of choline chloride, respectively)/kg basal diet and the RPC-supplemented feed was offered for 112 days after 12 days of adaptation. Average daily gain, dry matter intake, and nutrient digestibility were similar across treatments. The rumen pH was quadratically significant among treatments, with the lowest and highest pH observed from the 2.5 and 5 g/kg RPC supplement groups, respectively (P = 0.02). After feeding, the ruminal ammonia concentrations among treatments were different (P < 0.05), with the highest value observed from the 5 g/kg RPC supplement group. Microbial crude protein level was different, with the highest value recorded from the 0 g/kg RPC supplement group (P = 0.028). A linear effect (P < 0.05) was observed from short-chain fatty acid values among treatments before and after feeding. Serum albumin (P = 0.003) and albumin/globulin ratio (P = 0.002) had a quadratic effect, with the highest value found in the 0 g/kg RPC supplement group. Abdominal fat was higher in RPC-supplemented groups (P < 0.05) compared to the control group. Drip loss was 65% higher in RPC-supplemented groups compared to the control group (P = 0.012). Overall, the study results showed an effect of RPC on ruminal parameters, but the supplementation of low-level RPC did not improve the growth and slaughter performance of fattening lambs.