No abstract

A cooperative research study involving 1,080 litters was conducted at eight stations to determine the effects of additional feed during the last 23 d of gestation on reproductive performance of sows and on preweaning performance of their pigs. Primiparous and multiparous sows were fed fortified corn- or sorghum-soybean meal diets (14% crude protein). Control sows received 1.82 kg/d from March through November and 2.27 kg/d from December through February. Treated sows were fed an additional 1.36 kg of feed/d from d 90 of gestation to farrowing. Sows were allowed to consume the same diet ad libitum during a 21-d lactation. Additional feed in late gestation resulted in greater (P less than .001) sow weight gain from d 90 to d 110 of gestation (16.8 vs 9.0 kg) and greater (P less than .001) parturition-lactation weight loss (21.3 vs 16.4 kg). Total weight gain from breeding to 21 d of lactation favored sows that received extra feed (27.5 vs 22.7 kg; P less than .001). Sows receiving extra feed had more live pigs at farrowing (10.05 vs 9.71, P = .06) and at 21 d postpartum (8.35 vs 8.06, P = .09), and the pigs were heavier at birth (1.48 vs 1.44 kg, P = .003) and at 21 d (5.37 vs 5.20 kg, P = .006). Lactation feed intake and number of days from weaning to estrus were not affected by treatment. The results indicate that additional feed in late gestation improves reproductive performance in sows. In this study, the cost of an additional 31 kg of feed/sow was more than offset by the value of the additional sow weight gain (approximately 5 kg), the additional .3 of a pig/litter at weaning and the additional 2.6 kg of total litter weaning weight.

The objective was to determine the effects of floor temperature (20 or 30 C), supplemental heat (heat lamp or light bulb) and drying at birth on piglet survival to day 5. Rectal and infrared skin temperatures were taken on 326 piglets for the first 8 hr postpartum. Blood samples were obtained at birth, day 2 and day 5 and analyzed for thyroxine (T4), triiodothyronine (T3) and cortisol by radioimmunoassay. Weight of each pig was recorded at birth and on days 1, 2, and 5. Survival rates were monitored daily. It was postulated that piglets not dried at birth might have increased heat conservation because of vasoconstriction, which may increase the thermostability and survival of the neonate. Supplemental heat was the only treatment that increased rectal temperature after 3 hr postpartum. Skin temperature at 1/2 and 1 hr was increased by drying, and supplemental heat resulted in elevated skin temperatures from 5 to 8 hr postpartum. Plasma cortisol concentrations were elevated at 2 days of age among pigs not given supplemental heat, but no differences were detected at 5 days of age. Plasma T4 concentrations at 5 days of age were lower among male pigs, pigs on the 30 C floor and pigs given supplemental heat. No significant treatment effects were noted in T3 values at day 5. Pig weights and survival rate at 5 days of age were influenced by the interaction of floor temperature and drying pigs at birth. Pigs dried at birth and kept on the 20 C floor were heavier than those on the 30 C floor, whereas those not dried and kept on the 20 C floor weighed less than those on the 30 C floor. The rate of survival was significantly lower among pigs dried at birth and kept on the 20 C floor than among those not dried and on the 30 C floor (80.9 vs 97.2%), while drying had no effect on survival rate among pigs on the 30 C floor (94.5 vs 93.1%).

This study evaluated the effect of diets differing in standard ileal digestible (SID) lysine on lysine intake, growth rate, body composition and age at puberty on maternal line gilts. Crossbred Large White×Landrace gilts (n=641) were fed corn-soybean diets differing in SID lysine concentration (%, g SID lysine:Mcal ME); diets were not isocaloric. Gilts received three grower, finisher diet combinations: low (0.68% lysine grower, 0.52% lysine finisher), medium (0.79% lysine grower, 0.60% lysine finisher) or high (0.90% lysine grower, 0.68% lysine finisher). Grower diets were fed from 100 until 142days of age, and finisher diets were fed until they reached 220days of age. Body weight (BW), backfat thickness (BF), and loin depth (LD) were recorded every 28days. From 160-220days of age, gilts were exposed daily to vasectomized boars and observed for behavioral estrus. Gilts fed the low lysine diet had lower average daily gain and BW (P<0.05), but not fat depth:LD ratio. The percentage of gilts that displayed natural estrus by 220days of age was low but not different among dietary treatments (low 27.7%, medium 31.0% and high 37.7%, respectively; P=0.1201). Gilts fed the high and medium diets reached puberty 10 and 6days earlier, however, than gilts fed the low lysine diet (P<0.05). The rate of puberty attainment may have been less because all gilts contracted porcine epidemic diarrhea (PEDv) just as boar exposure was to begin for the first group of gilts. Results from the present study indicate that growth rate and age at puberty can be altered by ad libitum fed diets that differ in SID lysine concentration.

The objective of this study was to determine if body composition of developing gilts could be altered at the onset of estrus by ad libitum feeding diets differing in standard ileal digestible (SID) lysine and ME using levels that are within those used in practice by pig producers in the United States. Crossbred Large White × Landrace gilts ( = 1,221), housed in groups, were randomly allotted to 6 corn-soybean diets in a 2 × 3 factorial arrangement formulated to provide 2 SID lysine and 3 ME levels. Gilts received grower diets formulated to provide 0.86 (low) or 1.02% (high) SID lysine and 2.94 (low), 3.25 (medium), or 3.57 (high) Mcal of ME/kg from 100 d of age until approximately 90 kg BW. Then, gilts were fed finisher diets containing 0.73 (low) or 0.85% (high) SID lysine and 2.94 (low), 3.26 (medium) or 3.59 (high) Mcal of ME/kg until 260 d of age. The medium SID lysine and medium-ME diets were based on an informal survey from the U.S. commercial swine industry to obtain average levels that are currently being formulated for developing gilts. Gilts were weighed and backfat thickness and loin area were recorded at the beginning of the trial and then every 28 d. Feed intake (FI) was recorded as feed disappearance within the pen at 2-wk intervals. Lysine (g) and ME (Mcal) consumed were calculated based on diet formulations. At approximately 260 d of age, gilts were slaughtered and warm carcass weight and fat thickness were recorded. There were no differences between lysine or ME levels for growth and body composition, except for backfat, which was slightly greater for gilts fed a high-ME diet. Gilts fed high-ME diets had a lower FI but a greater ME intake compared with gilts fed low ME ( < 0.05). Additionally, gilts fed the high-ME diet had lower FI and lysine intake per kilogram of BW gain when compared with gilts fed low- or medium-ME diets ( < 0.05). However, there was no difference in the megacalories consumed per kilogram of BW gain among treatments ( > 0.05). Carcasses from gilts fed the high-ME diet were 3.3 and 2.5 kg heavier than those from gilts fed the low- or medium-ME diets ( < 0.05). Despite significant differences in the lysine:ME ratio in the diets, no changes in growth or body composition occurred, likely due to compensatory changes in FI in response to dietary ME content. Caloric efficiency (Mcal to deposit 1 kg of BW) was similar among treatments.