Lactation performance of sows injected with growth hormone-releasing factor during gestation and(or) lactation.

Fifty-two Yorkshire x Landrace gilts were equally allotted to four treatments: 1) controls, saline injections (CTL); 2) injections of 12 mg of growth hormone-releasing factor (GRF) (1-29)NH2 thrice daily (0700, 1500, and 2300) from d 100 of gestation until parturition (GEST); 3) injections of GRF thrice daily from d 3 to 29 of lactation (LACT); and 4) injections of GRF thrice daily during gestation (d 100 to parturition) and lactation (d 3 to 29) (GEST-LACT). Within 48 h of birth, litters were standardized to 9 +/- 1 pigs. Weights of the pigs were recorded weekly from birth (less than 24 h) until weaning (d 30) and on d 42 and 56. Weights of gilts at mating, d 110 of gestation, 1 d postfarrowing, and at weaning also were recorded. On d 24 of lactation, milk yield was estimated by the weigh-suckle-weigh method, and a representative milk sample was obtained the next day. Jugular vein cannulas were inserted into six sows per treatment on d 26, and a 6-h blood profile (sampling every 20 min from 0600 to 1200) was obtained on d 29. Daily feed consumption of sows was recorded throughout the study. Weights of the pigs at any one time or survival until weaning were not affected by treatments (P greater than .1). Sows injected with GRF during GEST (P = .05) and(or) LACT (P less than .01) were lighter than CTL sows at weaning; in addition, sows treated during lactation had less backfat (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)