Abstract
The purpose of the current study was to determine the effect of a single oral dose of L-tyrosine (50 g/animal) on milk yield, reproductive performance, and ovarian activity of dairy buffaloes. A total of 30 animals were used in this study having a mean live body weight of 548 kg and 3-5 of parity. Buffaloes were divided into three equal groups based on body weight and milk yield. Buffaloes in the first group were fed concentrate feed mixture and considered as a control group (G1), while the second and third groups (G2 and G3) received L-tyrosine oral 50 g/buffalo at 42 or 60 days of postpartum, respectively. Results revealed that buffaloes in G2 and G3 significantly (P<0.05) increased daily milk yield, 4% fat corrected milk yield (FCMY) and the percentages of fat and lactose as compared with G1. In addition, the L-tyrosine groups had the lowest somatic cell count in milk. As for reproductive traits, the interval periods from L-tyrosine treatment to oestrus incidence in G2 and G3 were 6.5 and 7.13 days, respectively, and the postpartum first service pros-treated interval and days open were significantly shorter in G2 and G3 than in G1. Number of services per conception observably reduced in G2 than in G3 and G1. Besides that, number of estrus cases and ovulatory cycles per buffalo and progesterone concentration during the ovulatory cycles significantly decreased in G2 and G3 compared with G1. Progesterone level was increased prior to estrus incidence in G2 and G3 than in G1. Moreover, L-tyrosine treated obviously decreased the number of ovulatory cycles for each buffalo and number of oestrus cases in G2 and G3 compared with G1. In addition, conception rate was greatly increased in G2 and G3 compared with G1.