Variation in ovulation rate and litter size

Selection for ovulation rate in swine: correlated response in litter size and weight.

Nine generations of direct selection for ovulation rate (OR) were evaluated to determine the magnitude of the correlated response in three litter size and two litter weight traits. A total of 387 Select line and 394 Control line litters were included in the ten generations of data. Realized heritabili ty of OR was .42 -+ .06 based on the regression of response (SelectControl) on weighted cumula...

Ovulation rate, litter size and prenatal losses in hair sheep of the French West Indies.

Ovulation rate (OR) and litter size (LS) were recorded in local hair sheep of Martinique and in local x Lacaune-viande crossbreeds, in order to assess prenatal losses. Local hair sheep LS and OR were 1.91 and 2.41, respectively. Prenatal losses increased with OR, from 0.22 (OR = 2) up to 1.50 (OR > 3). The ewes (69.7%) with LS = 1 had actually lost at least one ovum, against 25.9% of the ewes w...

Responses in ovulation rate, embryonal survival, and litter traits in swine to 14 generations of selection to increase litter size.

Eleven generations of selection for increased index of ovulation rate and embryonal survival rate, followed by three generations of selection for litter size, were practiced. Laparotomy was used to count corpora lutea and fetuses at 50 d of gestation. High-indexing gilts, approximately 30%, were farrowed. Sons of dams in the upper 10% of the distribution were selected. Selection from Generation...

Candidate gene analysis for loci affecting litter size and ovulation rate in swine.

A candidate gene approach was used to determine whether specific loci explain responses in ovulation rate (OR) and number of fully formed (FF), live (NBA), stillborn, and mummified pigs at birth observed in two lines selected for ovulation rate and litter size compared with a randomly selected control line. Line IOL was selected for an index of OR and embryonic survival for eight generations, f...

Candidate Reproductive Genes Do Not Explain Responses in Lines Selected for Ovulation Rate and Litter Size