6. Testing Different Methods for Predicting Sheep Milk Yield for 120 Days

The aim of the present study was to test some methods for a short control in predicting the 120-day milk production of ewes from the Synthetic Population Bulgarian Milk breed and to compare them with the standard method. The research was conducted in two consecutive years with 165 ewes of different lactations (from first to fourth) reared at the Institute of Animal Science (IAS) in Kostinbrod. The duration of the suckling period was 65 days. The milk for the control day was controlled in compliance with the official AC method of ICAR. The standard 120-day milk production was calculated. The predicted milk production was calculated on the basis of two controls during the milking period – the first and the third controls, the second and the fourth. The obtained information was processed with MS EXCEL, 2003. The effect of the method of calculating on the milk yield was specified by the method of least square means by ANOVA. The coefficients of determination of the regression equations for milk production prediction were calculated by applying regression analysis.
A highly significant effect of the predicted milk yield for 120 days was established only with the following formula: 120 (0.27 + 0.35x II control + 0.66x IV control) (F= 60.86***). The obtained predicted milk yield (136.45 l) significantly and vastly exceeded the milk yield according to the official method (106.45 l). The predicted milk production on the basis of the first and third controls (106.78 l) and the second and fourth (105.53 l) did not show any differences as compared to the milk
yielded by means of the standard method (106.45 l).