Lactation curves in some selected breeds of cows in Niger state, Nigeria
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Abstract
The aim of this study was to characterize and compare the lactation curves in some selected breeds of cattle in Niger State, Nigeria. The data for the study was obtained from three genotypes (Bunaji; n=350; Sokoto-Gudali; n=220 and Simmental; n=202) from the years 2014 to 2021 domiciled at Maizube® Farm. Lactation curves were namely the logistics, Gompertz, Woods, Wilmink and Cobby and Ledu were fitted on actual daily milk yield records. Estimators of the lactation parameters for each model were computed for each cow by AI-REML algorithm. A lactation curve was fitted in MATHPLOT using days in milk as a numerical variable. The adjustment criteria considered to compare models were persistency, adjusted R2 coefficient of determination and model selection criterion. The initial milk yield was predicted to be 4.37, 4.39, 4.95, 4.2 and 4.4kg for Logistic, Gompertz, Wood, Wilmink and Cobby and Ledu models in Simmental cows. Wood model (7.95kg/day) had the best scale factor for average milk yield followed by Logistic and Gompertz models (7.78kg/day) in Bunaji cows which was better than Wilmink (6.14kg/day) and Cobby and Ledu (6.93 kg/day) in Simmental cows. Gompertz model predicted the highest peak milk yield, followed by Logistic (8.04kg) and Wood (7.79kg) for Simmental and Sokoto Gudali cows. More research on the topic is required to reach significant recommendations.