Effect of challenge feeding during summer on the productive and reproductive performance and blood biochemical, metabolic and hormonal profile of crossbred lactating cows
*LRS, College of Veterinary Science and AH.
Lactating triple crossbred cows (18) with an average of 20–30 days postpartum period were randomly allocated to 3 groups each of 6 animals looking to their parity, body weight, daily milk yield and fat content in milk, and were fed individually as per the ICAR (1998). Animals of Group-I were fed 10 kg green cowpea, 20 kg green sorghum/maize and 4 kg dry baled grasses plus compounded concentrate mixture (Amul Dan) @ 33% of their milk production (apart from 1 kg for maintenance) and coarsely ground maize @ 1.0, 1.5 and 2.25 kg for cows producing daily < 8.0, 8–12 and >12.0 kg milk, respectively, with water showering at least 6 times each of 5 minutes duration between 12.30 and 3.30 PM. Animals of Group-II were fed as in group-I, but without water showering, while Group-III served as farm control (fed daily 10 kg green cowpea, 15 kg green sorghum/maize and 2 kg dry baled grasses plus Amul Dan @ 50% of their milk production without water showering). The observations on body weight, daily milk yield, fat content in milk and the feed intake were recorded at weekly, while jugular blood samples were collected at fortnightly intervals for estimating the plasma profile of certain hormones, enzymes, metabilities and biochemical constituents. Intervals for first estrus and fertile estrus postpartum were also recorded. DM intake and gain in body weight were little better with production of 400 gm more milk daily in animals under challenge feeding groups as compared to farm control, although the fat content in milk was significantly higher in control group. Challenge feeding neither influenced the plasma progesterone and cortisol profile nor ALP activity, but the levels of transaminases (AST, ALT) were lower particularly in water showered group as compared to farm control. Blood glucose and triglyceride levels were significantly (P<0.01) higher and plasma total protein and BUN lower in challenge feeding groups as compared to farm control. However, plasma total cholesterol and phosphorus contents were significantly lower and calcium content higher in animals under challenge feeding groups, particularly with water showering, as compared to farm control, but the magnesium levels did not vary between them. Further there was an apparent reduction in the interval for first oestrus postpartum by 35 and 55 days in animals under challenge feeding with and without water showering, respectively, as compared to farm control group, and thereby the service period by 40 days. Thus it was inferred that challenge feeding together with supplementation of energy and water showering during peak hours of summer stress has beneficial effect towards maintaining optimum homeostasis of various blood constituents and thereby improving the productive and reproductive efficiency of lactating crossbred cows.
Challenge feeding, early lactation, summer stress, productive performance.