Abstract
Lactation curves are a graphical representation of the milk production profile of a doe from parturition to drying up. Their shape provides information about the productivity of the doe and offers a means of explaining features of the milk production patterns of each animal. A total of 2732 daily morning milk records from 610 does of the Kenyan Alpine dairy goats’ genetic groups (50% Alpine, 75% Alpine, 87.5% Alpine and > 87.5% Alpine) and local goats (0% Alpine) kept in small-holder farms were used to evaluate factors affecting milk yield and to examine the characteristics of their lactation curve. A nonlinear mixed model was used to fit the lactation curves to all does simultaneously. The Wood’s (1967) equation was fitted within each genetic group and parity to generate genetic group and parity lactation curves. The mean lactation period was 218 ± 46 days and the model accounted for 88% of the total variation. Significant differences (P 87.5% Alpine genetic groups respectively. Genetic group did not significantly affect rate of increase to peak yield (P > 0.05) and rate of decline from peak (P > 0.05) or persistency (P > 0.05). Parity significantly affected rate of increase to peak, rate of decrease from peak and persistency (P < 0.01). The month of kidding significantly affected the rate of increase to peak (P < 0.05) and persistency, but not rate of decrease from peak. The synchronization of breeding with season has a practical implication for the maximization of lactation yield when considered in combination with other biological and economic constraints. The superior production of the pedigree animals supports the development of composite breed types in Kenya to take advantage of the fitness of indigenous breeds, the productivity of imported dairy breeds, heterosis, and the potential for selection within the composite to improve productivity in later generations.
Highlights
The term “lactation curve” is used to refer to the curve representing the rate of milk yield with advance in lactation
This study provides the basic framework needed for the future development of computationally feasible techniques to evaluate the dairy potential of a Kenya Alpine dairy goat given the initial milk production and a future time, t
Wood’s equation fitted well the lactation curves of the different genetic groups with R2 values ranging from 85% to 91%
Summary
The term “lactation curve” is used to refer to the curve representing the rate of milk yield with advance in lactation. Saanen and Toggenburg crosses had greater milk production, lactation length and efficiency (milk production/post-kidding body weight) than Granadina and Nubian crosses or local does. Average increase for milk production, lactation length and efficiency over local goats for low-grade Alpine was reported to be 46%. Effects of year of kidding, season of kidding and age were reported to be most significant with goats having two or more kids at birth having greater milk production efficiency and body weight than goats with one kid. As reported by [5], daily milk yield increased rapidly from kidding to a peak in 35 days, followed by a gradual decline until milking was no longer practical. An abrupt decline in milk yield after the peak increases production costs because yield was distributed less over the complete lactation [5]
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