Investigating the effect of the level and ratio of lysine to methionine in the feed during the transition period on the performance and health of Holstein cows after calving

Abstract

Introduction: The beginning of lactation in dairy cows is associated with a negative balance of energy and protein. The availability of sufficient protein and the appropriate ratio of lysine to methionine during this period can increase milk production, improve liver lipid metabolism, and improve the functioning of the immune system. Materials & Methods: A total of 48 Holstein cows were used from the stage of 28±5 days before calving to 21 days after calving in the form of a completely random design in four treatments and in 12 repetitions. The experiment was carried out in PEGAH SELMAS Agriculture and Animal Husbandry Company in 2021. Experimental treatments included: LPLM (low protein and low methionine), LPHM (low protein and high methionine), HPLM (high protein and low methionine) and HPHM (high protein and high methionine). Results: Before parturition two levels of protein 13.1 and 15.1 and also two levels of lysine to methionine ratio 2.8 and 3.5 and after parturition also with two levels of protein 16.1 and 18.7 with a ratio of lysine to methionine 2.8 and 3.5 were fed. In the treatments that had higher protein (HPHM and HPLM), the dry matter intake before calving was increased by 1.1 kg and after calving by 1.5 kg. Also, the dry matter intake was 0.5 kg in HPHM treatment more than HPLM treatment. Rations were balanced using NRC software and all cows received the same amount of energy. corn gluten meal was also used to change the ratio of lysine to methionine; which has the highest ratio of methionine to lysine among common feeds in the country. The effect of diet on average daily milk production, daily fat production, protein and lactose traits was significant; But it had no significant effect on BW traits prepartum and BW postpartum. HPHM treatment caused a significant increase (P<0.01) in dry matter intake pre and postpartum, daily milk production, daily fat, compared to other treatments. Conclusion: The results of this research showed that HPHM treatment was more practical than other treatments; Because the increase in the protein level caused an increase in milk production, as well as an improvement in the health status of the animals and other traits measured postpartum.