Estimation of energy Balance Curve in dairy cows using Wood function

Résumé

This study was conducted to investigate whether Wood function can adequately explained the energy balance of dairy cows during lactation and if so, how accurate could energy balance ( EB) be predicted using the wood function. Data for the study were collected from 13 primiparous cows and 18 multiparous (F1) Friesian x Bunaji cows at National Animal Production Research Institute (NAPRI), Zaria. The results revealed that the Wood function fitted the EB curve adequately, it explained over 73.57% of the variation in EB of the dairy cows with a very low residual error (0.50592). The EB curve parameters; initial EB of the dairy cows after calving (a), the ascending slope parameter up to peak EB (b) and descending slope parameter (c) of the curve models and their standard error (SE) were -1.411±0.56, 3.239±0.406 and -0.293±0.034, respectively. The model for
prediction of EB over a period of time t was developed as Yt = -1.411t 3.239e -0.293. The EB curve pattern shows that the animals had negative energy balance (NEB) at the initial lactation (within the first 2 weeks of lactation) and recovered to positive energy balance (PEB) and rose faster to the peak at approximately 9 to 10 weeks and then maintain some persistency and thereafter decline at a slower rate to negative EB (during the advanced pregnancy). Based on the foregoing, it is concluded that the Wood function adequately explained the variation in EB of Friesian x Bunaji dairy cows during lactation.