Analyses of Feed and Energy Intakes During Lactation for Three Breeds of Sows

Daily feed intakes from 993 lactation records from 3 breeds of sows (42 Duroc, 405 Landrace, and 358 Yorkshire sows) were evaluated over a 19-mo period. Mixed models were evaluated for the Bridges, negative exponential, and generalized Michaelis-Menten functions. The generalized Michaelis-Menten function with 2 random effects provided the best fit to both daily feed intake (residual SD = 0.93 kg/d) and ME intake (residual SD = 3.04 Mcal/d). Duroc sows had lower (P < 0.001) feed and ME intakes than Landrace and Yorkshire sows. Feed and ME intakes were less for the summer season (June 15 to September 15) than for the other 3 seasons. Predicted mean ME intake (d 1 to 19) had significant (P < 0.001) relationships with number weaned (NW; ME intake, Mcal/d = 16.84 + 1.445 NW - 0.0692 NW2) and 21-d litter weight [ME intake, Mcal/d = 21.42 + 0.0454 (21-d litter weight, kg)]. Sows with greater than average 21-d litter weights consumed only 12 to 14% of the additional ME required for the additional milk production. A transient reduction in feed intake was defined as when daily feed intake was 1.6 residual SD less than the predicted daily feed intake for 2 or more days. The incidence of transient reductions in feed intake was not affected (P > 0.10) by stage of lactation (68 early, 77 mid-, and 82 late lactation). The incidence of transient reductions in feed intake was affected (P < 0.05) by season, with incidence rates of 18.8, 16.3, 22.2, and 16.3% for summer, fall, winter, and spring, respectively.