Genetic comparison of milk production and composition in three maternal rabbit lines

Abstract

The aim of this study was to compare 3 Spanish maternal rabbit lines (A, V and LP) in terms of milk production and composition. These lines were founded on different criteria but selected for litter size at weaning. A total of 194 mature does in their third or higher parity were used. The milk yield of does was recorded at 1, 2, 3, 4, 8, 9, 10, 11, 15, 16 and 17 d post-partum (dpp). The milk production traits studied were weekly milk yield (WMY; g/wk) and milk conversion ratio (MCR; grams of litter gain per grams of milk suckled during the first 21 dpp). The milk composition traits studied were fat (%), protein (%), ash (%), lactose (%) and total solids (%). The milk samples to be analysed were collected from each doe at 18 dpp. Data were analysed using single trait mixed and fixed models with and without covariates; the covariates were number born alive (NBA) and doe weight at kindling (DW). The overall mean of WMY, during the first 3 wk, was 1547±16 g/wk. Milk yields during the different lactation weeks were for line A 872±39, 1503±39 and 1865±39 g for first, second and third lactation weeks, respectively. In line V, the corresponding values were 919±35, 1633±35 and 2004±35 g, and in line LP, they were 1043±36, 819±36 and 2254±36 g. Means of MCR were 0.41±0.01, 0.41±0.01 and 0.42±0.01 for A, V and LP lines, respectively. Overall means of fat, protein, ash, lactose and total solids (%) were 14.62±0.17, 11.10±0.07, 1.89±0.04, 2.67±0.12 and 30.27±0.24, respectively. The differences between lines for milk production traits were significant except for MCR, while the differences between lines for milk composition traits were not significant. NBA had significant effects on all milk yield traits but had no significant effects on milk composition traits. DW only had a significant effect on weekly milk yield. The parity order had no significant effect either for milk production traits or milk composition traits in multiparous does, except for ash %.