EFFECT OF ORAL L-CARINITINE ADMINISTRATION ON PRODUCTIVE AND REPRODUCTIVE PERFORMANCES OF CROSSBREED CATTLE

The objective of this study was to evaluate the effects of oral L-carnitine (LC) administration on milk yield and composition, estrous activity and reproduction performance of crossbreed cows. A total of 30 crossbreed cows  at early post-partum, weighing 432.7±23.5 kg LBW, aging 3.5-4 years and in 1-3 parities were divided into two similar groups according to LBW and age. Cows in the 1^st group were fed a basal diet and was considered as a control group (G1). While, cows in the 2^nd group (G2) were fed the same diet and treated orally with 3 g LC/cow/day for 120 days postpartum. Cows were machine milked and milk yield was calculated as actual (AMY) or 4% fat corrected milk (FCMY) yield. Milk composition and somatic cell count (SCC) were determined. Estrus was detect and cows in heat were artificially inseminated. Then, number and length of estrous cycles from calving up to conception was recorded. Postpartum 1^st estrus (PPFEI) and 1^st service (PPFSI) intervals, number of services per conception (NSC), service period length (SPL), days open (DO) and conception rate (CR%) were calculated. Pregnancy was diagnosed by rectal palpation on day 60 post-insemination. Results show that daily milk yield as AMY or FCMY of cows increased (P<0.05) by about 19.3% in G2 than in G1. Percentage of fat and protein in milk increased (P<0.05), while SCC decreased (P<0.05) by about 16.9% in milk of G2 as compared to G1. Average number of estrus cases and estrous cycles/cow was lower (P<0.05) in G2 than in G1. Average P4 concentration and P4 peak during the estrous cycle was higher (P<0.05) in G2 than in G1. Average P4 concentration during PPFEI was lower (P<0.05) in G2 than in G1. Average of PPFEI, PPFSI, SPL, DO and NSC were lower (P<0.05) in G2 than in G1. CR was higher (P<0.05) in G2 (93.33%) than in G1 (66.67%). In conclusion, the present study indicated beneficial effects of L-carnitine treatment (3 g/cow) for 120 days during early lactation period on milk production and reproductive performance of crossbreed cows during the first four months of lactation.