Effect of teat number, teat abnormalities and underline length on litter sizes and weights at 21 and 42 days in swine.

Data from 80 first-litter purebred and crossbred gilts of Duroc and Landrace breeding were analyzed to determine the effects of traits associated with their udder on the sizes and weights of their litters at 21 and 42 d. Traits measured on each first-litter gilt included: number of teats in front of the navel; number of functional teats; number of inverted and pin nipples; length of the underline; body length and weight at parturition. When the litter size nursed at 1 d was held constant, litter size at 21 and 42 d was not influenced by number of teats in front of the navel, number of functional teats, number of inverted nipples, number of pin nipples, body length or weight at parturition. First litter gilts with shorter underlines tended to raise larger litters at 21 and 42 d (P less than .05). Litter weights at 21 and 42 d were not affected by the number of teats in front of the navel, number of functional teats, number of inverted nipples, or by the number of pin nipples when the size and weight of the litters born alive were held constant. First-litter gilts with shorter body lengths tended to have heavier litters at 21 d, (P less than .05) while those with shorter underlines (P less than .05) and those that weighed more at parturition (P less than .10) tended to have heavier litters at 42 d. Results from this study are interpreted to indicate a replacement-gilt selection program that applies selection pressure for only increased teat number and against teat abnormalities seems unwarranted.