Impact of the subclinical small ruminant lentivirus infection of female goats on the litter size and the birth body weight of kids.

A longitudinal study was conducted in a single dairy goat herd to investigate the relationship between subclinical small ruminant lentivirus (SRLV) infection in does and litter size (LS) or birth body weight of kids (BW). Each year kids born to seropositive and seronegative does were weighed before the first consumption of colostrum. LS and BW of each kid were recorded. BW was significantly negatively linked to LS (p = 0.006) - singletons weighed (mean ± SD) 4.20 ± 0.67 kg, twins - 3.75 ± 0.62 kg, and triplets and quadruplets - 3.38 ± 0.47 kg. Male kids were significantly heavier than female kids in twin litters (3.97 ± 0.53 kg vs. 3.52 ± 0.60 kg; p < 0.001) and triplet or quadruplet litters (3.62 ± 0.40 kg vs. 3.17 ± 0.43 kg; p < 0.001). However, BW of male and female kids from singleton litters did not differ (4.31 ± 0.71 kg vs. 4.07 ± 0.65 kg; p = 0.154). Then, two mixed models were developed to assess the relationship between LS (mixed Poisson log linear regression model) or BW (mixed linear model) and SRLV infection in the doe, controlling for potential confounders such as the effect of an individual doe, year in which the parturition took place, parity and kid's sex. Neither LS nor BW proved to be significantly associated with SRLV infection (p = 0.788 and p = 0.214, respectively). On this basis it was concluded that LS and BW were not affected by the subclinical SRLV infection of a doe.