Relationships between piglet growth rate and mammary gland size of the sow

An experiment was conducted to study whether piglet growth rate is related to mammary gland size. It involved three primiparous sows and four multiparous sows that were fed ad libitum during the lactation period. The piglets received no creep feed. The weight and teat order of the piglets were recorded. The sows were slaughtered after approximately 4 weeks of lactation (25–28 days). The amounts of mammary tissue and mammary DNA were larger in multiparous than in primiparous sows, and the concentrations and amounts of mammary RNA as well as mammary RNA/DNA ratios were highest in the front glands, intermediate in the middle and lowest in the rear glands. Average daily gain of the piglets was of the same magnitude regardless of gland position in the primiparous sows. In the multiparous sows, the piglets suckling the front teats had the highest gain while those suckling the middle teats had intermediate gain and those suckling the rear teats had the lowest gain. Average daily gain of the piglets in the lactation period was positively correlated to the amount of mammary tissue (0.35), mammary DNA (0.41) and mammary RNA (0.31), while correlations to mammary RNA concentration (0.28) and RNA/DNA ratio (0.22) did not reach significance. There were no significant correlations between piglet start weight and any of these mammary gland compositional traits.  2001 Elsevier Science B.V. All rights reserved.