Impact of corn silage substitution for dry alfalfa on milk fatty acid profile, nitrogen utilization, plasma biochemical markers, rumen fermentation, and antioxidant capacity in Mahabadi lactating goats

Abstract

This study aimed to investigate the effects of substituting conventional dry forage with corn silage, a more cost-effective supplementary feed, on a variety of parameters in lactating Mahabadi goats, native to arid and semi-arid regions. A total of fifty lactating Mahabadi goats, aged between 2 and 5 years and weighing an average of 45.3 ± 7.20 kg, were randomly allocated into two experimental groups. The experimental treatments consisted of a control diet and a diet incorporating corn silage at 20 % of dry matter (DM). Various measurements were conducted to assess milk compositions, fatty acid profiles, rumen fermentation parameters, selected plasma biochemical parameters, nitrogen balance, and antioxidant capacity. The results revealed that the substitution of dry forage with corn silage had no statistically significant impact on milk yield, dry matter intake (DMI), body weight, as well as the proportions of monounsaturated and unsaturated fatty acids, and specifically C18:1C9 in milk, non-esterified fatty acid content in milk, rumen concentration of volatile fatty acids (VFA), microbial nitrogen, and nitrogen balance (p > 0.05). Nonetheless, this substitution led to a reduction in the percentage of milk polyunsaturated fatty acids and plasma urea nitrogen content (p < 0.05). It is noteworthy that goats fed with corn silage exhibited a notably higher antioxidant capacity in rumen liquor (p < 0.05), plasma, and milk (p < 0.01) compared to those receiving the control diet. The substitution of conventional dry forage with corn silage exhibited no adverse effects on the performance of lactating Mahabadi goats. On the contrary, it contributed to an enhancement in the antioxidant status. These findings offer valuable insights for optimizing dietary composition by incorporating corn silage at 20 % of DM, thereby improving milk quality, reducing costs, and promoting overall health in lactating goats, particularly within arid and semi-arid regions.