Relationship of blood metabolites with reproductive cyclicity in dairy cows

A total of 40 dairy cows in early lactation (60 to 90 days) of four different breeds were selected, comprising 10 animals each from Holstein Friesian (HF), Jersey (J), Achai (ACH) and F₁ (HF x Sahiwal). All cows were multiparous with body weight 250–400 kg and milk production ranged from 3 to 12 kg/day. Blood samples were collected from each animal at fortnight intervals for 90 days. In the present study, 65% of cows reestablished estrus while 35% cows remained anestrous, 80% of Holsteins showed estrus followed by 70% of Jersey and F₁ cows while in Achai breed showed only 40% and 60% cows remained anestrous. Blood glucose and daily milk yield significantly affected post partum estrus (P<0.01) while serum total protein and triglycerides concentration in blood did not affect post partum estrus. The serum glucose level was lower (39.93 ±3.14 mg/dl) two months before and showed an increasing trend (49.63 ± 2.47 mg/dl) towards commencement of estrus as well as during estrus (48.20 ± 2.42 mg/dl) and then a declining trend was observed. Mean concentration of serum glucose was significantly higher in Jersey (52.50 ± 2.09 mg/dl) followed by F₁ (39.68 ± 1.45 mg/dl), HF (38.85 ± 1.77 mg/dl) and Achai (33.30 ± 2.17 mg/dl) respectively. Breed type significantly affected blood glucose (P < 0.05) in jersey cows whereas both blood glucose and triglycerides were significantly affected (P < 0.001 and P < 0.05, respectively) in F₁ cows.