Effect of calcium salt of flaxseed oil and zinc-methionine supplementation on growth performance, digestibility, feeding behavior, and rumen and blood parameters of fattening lambs.

The present experiment was aimed at evaluating the effect of using the Ca-salt of flaxseed oil (CFO) in diets containing different levels of zinc by including zinc-methionine supplementation (ZMT) on the performance, feeding behavior, rumen and blood parameters in fattening lambs. For this purpose, 44 3-month-old lambs were allocated to one of four treatments: a diet without CFO and ZMT (NCFO-NZMT), a diet containing 0.083% ZMT without CFO (NCFO-ZMT), a diet containing 3% CFO without ZMT (CFO-NZMT), and a diet containing 3% CFO and 0.083% ZMT (CFO-ZMT). The duration of the experiment was 84 days. ZMT supplementation affected plasma zinc (Zn) content, as ZMT-fed lambs had a greater plasma Zn concentration than NZMT-fed lambs. Final BW, ADG, and DMI increased with the addition of CFO to the feed. Feeding CFO increased crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibilities. Additionally, CFO-fed lambs had a greater rumen pH at day 84 and propionate proportion than NCFO-fed lambs. CFO addition increased glucose, cholesterol, and high-density lipoprotein concentrations and decreased blood urea nitrogen concentration. Also, alkaline phosphatase and aspartate aminotransferase concentrations were greater in CFO-fed lambs than in NCFO groups. Lambs fed CFO had longer eating, ruminating and chewing time and shorter standing time. Overall, our results indicated that supplementation of the diet with 3% CFO improved lambs performance. Conversely, adding 0.083% ZMT to the basal diet containing 31 mg Zn/kg DM had no effect on performance, indicating that this level of zinc in the basal diet was sufficient to support the growth of fattening lambs. However, the results should be interpreted in context of the conditions employed, as the greater metabolizable energy in CFO diets than NCFO diets (3.25 vs. 3.14 Mcal/kg) is limitation of the study.