Analysis of lactation feed intakes for sows including data on environmental temperatures and humidity

Abstract

ABSTRACT Daily feed intakes (DFI) of 565 lactation records were evaluated for sows of 2 genetic lines, PIC C-22 and L-42. Sows were fed ad libitum during the entire 21-d lactation period with a diet supplemented with either 0 or 0.3% betaine-HCl. Sows were fed corn–soybean based diets (3.32 Mcal of ME/kg). The DFI data were fitted to generalized Michaelis-Menten functions of day of lactation. The generalized Michaelis-Menten function {DFI i, t (kg/d) = DFI 0 + (DFI A − DFI 0 )( t / K ) C /[1 + ( t / K ) C ]} with 2 random effects for DFI (dfi A i ) and intercept (dfi 0 i ) with K as a linear function of dfi 0 i provided the best fit to the DFI data (R 2 = 0.474). The addition of a single covariate including daily degree-hours above 24°C (DGH24), daily maximum temperature (MaxT), or daily mean temperature (MeanT) of the current day were considerable ( P P 0 i and dfi A i . Betaine-supplemented sows had a 0.27 kg/d greater mean for dfi A i ( P = 0.004). Substantially greater DFI was found at the end of lactation in betaine-supplemented parity 1 and parity 2 sows ( P = 0.012 and 0.005, respectively). Parity was important for both random effects ( P A i ( P = 0.006 and 0.049, respectively).