The effect of different doses of mixed ligand complexes of zinc, manganese, and cobalt on the milk productivity of dairy cows during lactation periods

Abstract

Using trace element salts in animal feed can lead to the rapid contamination of the environment with these metals due to their low biological availability to animals. Organic compounds of trace elements are much better absorbed by animals, who perform better at reduced levels of these feed additives. This article presents comprehensive study results on the effect of mixed-ligand complexes of trace elements (Zn, Mn, and Co) combined with organic selenium (Suplex Se) on the milk productivity of high-yielding cows of various breeds during different lactation periods. The work is relevant due to the increasing deficiency of trace elements in the soil–feed–ration system in intensive dairy farming conditions, and the low bioavailability of traditional inorganic trace element salts. This study aimed to demonstrate the feasibility of replacing sulfate forms of zinc, manganese, and cobalt with mixed ligand complexes and to establish the optimal concentrations of these complexes in cow diets during the lactation period. The experiment was conducted on 50 cows from three breeds (German Holstein, Ukrainian Black-and-White Dairy, and Ukrainian Red-and-White Dairy) using the analogue group method, forming one control group and four experimental groups. Productivity, milk quality, and feed consumption were studied over the first, second, and third 100-day periods of lactation. We have established that using organic forms of micronutrients reliably increases the average daily milk yield (P < 0.001), enhances gross milk production with a 4 % fat content, and reduces metabolic energy expenditure per unit of production. The highest milk productivity rates during the first 100 days were achieved with a diet containing 60.8 mg of zinc (Zn), 60.8 mg of manganese (Mn), and 0.78 mg of cobalt (Co) per kg of dry matter (DM) in the form of mixed ligand complexes. During the second 100 days, an optimal effect was achieved with lower concentrations of trace elements (35 mg Zn and Mn, and 0.4 mg Co per kg of DM). Using chelated forms of trace elements also led to a moderate increase in milk’s fat and protein content, as well as a 4–6 % reduction in feed consumption. The results confirmed that the source of these trace elements in the diet is their mixed-ligand complexes. Dairy cows require less than the recommended amount of zinc, cobalt, and manganese.