Coefficients of repeatability for colostrum and milk composition of PLW and PL sows over three consecutive lactations

• Hitherto not carried out of such studies for a sows.
• Was calculated the coefficients of repeatability for colostrum composition of sows.
• The highest repeatability was estimated for colostrum lactose and solids content.
• In the milk sows lactose content has the highest coefficient of repeatability.

To date, there have been no studies determining the coefficients of heritability or repeatability for colostrum and milk composition of sows in successive lactations. In the case of sows, estimation of such coefficient of repeatability may give a preliminary indication of whether these traits can be used in the breeding and selection of pigs. The aim of the experiment was to make preliminary estimates of the coefficients of repeatability for the content of the Polish Large White (PLW) and Polish Landrace (PL) sow colostrum and milk components over three consecutive lactations. Subjects were 72 sows of the PLW (30 sows) and PL breeds (42 sows). During three consecutive lactations, samples of colostrum and milk on day 14 of lactation were collected from the first, third and sixth teats of the sows (each sample from teats 1, 3 and 6 totalled 50 ml in volume). In total, 432 samples of colostrum and milk were collected from sows of the two breeds. The samples were analysed for fat, crude protein, lactose, solids, and non-protein solids. Summarizing the results, it is concluded that the highest coefficient of repeatability was estimated for colostrum lactose and solids content over two consecutive lactations: second and third (r=0.3). Also in the milk of second- and third-lactation sows, the lactose content was characterized by the highest coefficient of repeatability (r=0.18). Considering the three consecutive lactations, it was found that colostrum produced by the sows had a consistent content of lactose (r=0.18) as well as solids (r=0.17) and protein (r=0.16). Therefore, it can be stated that the lactose content of sow colostrum in the first lactation could be indicative of a female's predisposition to produce colostrum and milk with similar lactose content over two consecutive lactations.