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A cooperative regional study involving 850 litters was conducted at five experiment stations (Arizona, Florida, Oklahoma, Texas, and Virginia) to assess the effects of feeding 220 mg/kg of chlortetracycline (CTC) from 1 wk before to the initiation of the breeding season to 15 d after the breeding season and(or) from 110 d of gestation through lactation on reproductive performance of sows (2 x 2 factorial). Sows were fed 1.82 kg/d (2.27 kg during December, January, and February) during the breeding period and before farrowing. Feed was consumed on an ad libitum basis during lactation. Feeding CTC during the breeding season increased litter size at birth (10.8 vs 10.3; P < .05) and decreased feed consumption (5.4 vs 5.5 kg/d; P < .05) in the subsequent lactation period. Feeding CTC during lactation reduced lactation weight loss in sows (4.3 vs 6.1 kg; P < .07). Feeding the antibiotic at breeding had no effect on conception rate; however, feeding the antibiotic during lactation improved subsequent conception rate at the first service (80 vs 73%; P < .10) and overall conception rate (89 vs 84%; P < .05). This indicates that some carryover effect of feeding CTC during lactation occurred during the subsequent breeding period. Station x treatment interactions were observed for survival rate to 21 d (P < .05) and to weaning (P < .06). Overall, survival rates were not greatly affected by antibiotic feeding. No treatment interaction was observed for any trait measured, indicating that the effects of CTC during the breeding and lactation periods were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

A cooperative experiment involving 999 litters was conducted at seven stations to assess the reproductive performance of gilts and sows fed different levels of energy during gestation and lactation (21 d) for three consecutive parities. Treatments consisted of two gestation (G) and two lactation (L) diets in a 2 x 2 factorial arrangement. Gestation treatments were diets fed to provide normal (5.9 Mcal/d, NG) or high (7.4 Mcal/d, HG) energy intake; lactation treatments were diets that contained 0 (NL) or 9% added fat (HL). Sows were provided ad libitum access to feed during the lactation period. Feeding the higher energy level during gestation increased pig birth weight (P < .01) and pig weight gain to weaning (P < .01). Sows that had been fed the higher level of energy during gestation (HG) ate less feed during lactation (P < .01) and lost more weight during lactation (P < .01). Increasing lactation energy intake by adding fat resulted in greater pig weight gains to 21 d of age (P < .01). Sows fed the HG-NL combination had fewer pigs on d 21 than all other treatment groups (G x L; P < .01). There was a G x L x parity interaction (P < .05) for days to estrus after weaning. Sows on the NG-HL or HG-NL treatments had increased days to estrus in Parity 1 (P < .05), whereas those on the NG-NL treatments had increased days to estrus in Parities 2 and 3 (P < .05). The HG-HL treatment minimized days to postweaning estrus during the three-parity study.(ABSTRACT TRUNCATED AT 250 WORDS)

A cooperative regional study involving 850 litters was conducted at five experiment stations (Arizona, Florida, Oklahoma, Texas, and Virginia) to assess the effects of feeding 220 mg/kg of chlortetracycline (CTC) from 1 wk before to the initiation of the breeding season to 15 d after the breeding season and(or) from 110 d of gestation through lactation on reproductive performance of sows (2 x 2 factorial). Sows were fed 1.82 kg/d (2.27 kg during December, January, and February) during the breeding period and before farrowing. Feed was consumed on an ad libitum basis during lactation. Feeding CTC during the breeding season increased litter size at birth (10.8 vs 10.3; P.05) and decreased feed consumption (5.4 vs 5.5 kg/d; P.05) in the subsequent lactation period. Feeding CTC during lactation reduced lactation weight loss in sows (4.3 vs 6.1 kg; P.07). Feeding the antibiotic at breeding had no effect on conception rate; however, feeding the antibiotic during lactation improved subsequent conception rate at the first service (80 vs 73%; P.10) and overall conception rate (89 vs 84%; P.05). This indicates that some carryover effect of feeding CTC during lactation occurred during the subsequent breeding period. Station x treatment interactions were observed for survival rate to 21 d (P.05) and to weaning (P.06). Overall, survival rates were not greatly affected by antibiotic feeding. No treatment interaction was observed for any trait measured, indicating that the effects of CTC during the breeding and lactation periods were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

A cooperative experiment involving 999 litters was conducted at seven stations to assess the reproductive performance of gilts and sows fed different levels of energy during gestation and lactation (21 d) for three consecutive parities. Treatments consisted of two gestation (G) and two lactation (L) diets in a 2 x 2 factorial arrangement. Gestation treatments were diets fed to provide normal (5.9 Mcal/d, NG) or high (7.4 Mcal/d, HG) energy intake; lactation treatments were diets that contained 0 (NL) or 9% added fat (HL). Sows were provided ad libitum access to feed during the lactation period. Feeding the higher energy level during gestation increased pig birth weight (P.01) and pig weight gain to weaning (P.01). Sows that had been fed the higher level of energy during gestation (HG) ate less feed during lactation (P.01) and lost more weight during lactation (P.01). Increasing lactation energy intake by adding fat resulted in greater pig weight gains to 21 d of age (P.01). Sows fed the HG-NL combination had fewer pigs on d 21 than all other treatment groups (G x L; P.01). There was a G x L x parity interaction (P.05) for days to estrus after weaning. Sows on the NG-HL or HG-NL treatments had increased days to estrus in Parity 1 (P.05), whereas those on the NG-NL treatments had increased days to estrus in Parities 2 and 3 (P.05). The HG-HL treatment minimized days to postweaning estrus during the three-parity study.(ABSTRACT TRUNCATED AT 250 WORDS)

Crossbred neonatal pigs from spring and summer farrowings were used to evaluate the systemic humoral immune response in porcine serum after ingestion of soy protein. At 10 to 12 d of age (average BW 3.8 kg), pigs were randomly allotted to three treatment groups according to litter, weight, and sex. Treatments were intermittent gavage feedings two or three times daily for six consecutive days with nonfat dry milk (NFDM) or textured vegetable protein (TVP) and a nongavaged control group. Pigs were weaned at 20 to 22 d of age (average BW 5.7 kg) and fed a corn-soybean meal-based starter diet. Total serum immunoglobulin G (IgG) and IgG concentrations specific for soy protein were measured by ELISA. Blood samples were taken at 1 d of age after colostrum intake and at 4-d intervals from the beginning of treatment to 31 d of age. When averaged from d 1 to 31, spring-farrowed pigs had greater (P less than .005) total IgG and soy-protein-specific IgG concentrations than did summer-farrowed pigs (8.70 vs 6.51 mg/mL and 1.59 vs .55 micrograms/mL, respectively). Total serum IgG concentrations changed with time (P = .005); they initially decreased, then recovered after weaning. These changes were independent of treatment, sex, or farrowing season. Soy-protein-specific IgG concentrations also changed with time (P = .003); however, this trend was dependent on season (P = .014). Summer-farrowed pigs exhibited a more rapid and severe decrease in serum IgG concentrations specific for soy protein than did spring-farrowed pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Summary Wet feeding and dry feeding of a starter diet for weaned pigs were compared at three stations Virginia Polytechnic Institute and State University (VPI), Clemson University (CLEM) and the University of Arkansas (ARK). Ninehundred and thirty-six pigs (average weight 7.8 kg) were used in all. A commercial liquid self-feeder provided the wet diet in an approximate diet to water ratio of 1:2. Self-feeders were used to provide the diet in a dry form. Daily gain and daily feed did not differ (P>.10) between pigs fed by the wet method and those fed by the dry method. Feed to gain ratio favored pigs fed the diet in a dry form. A significant station x treatment interaction for daily gain was observed. At VPI, gain favored dry-fed pigs, while at ARK it favored wetfed pigs; there was no difference in gain between dry- and wet-fed pigs at CLEM. Improved daily gains reflected greater daily feed intakes. These results suggest that there is no major difference in the performance of pigs fed wet and dry diets; thus, the decision to use a liquid or wet feed should be based solely on the merits of the feeding system.

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.

Eight fetal pigs, in utero, were injected ip with 20 microCi/fetus [U14C]-fructose between d 55 and 65 pregnancy. The isotope was allowed to equilibrate between blood and tissues within injected fetuses for a period of 240 min. Fetal pigs were then sacrificed and nucleic acids were extracted from cold tissue homogenates of skeletal muscle and liver. Nuclide disintegrations per minute recovered in extracted DNA and RNA were used to calculate incorporation of labeled C from fructose. The recovery of labeled C per mmol of nucleic acids from skeletal muscle was greater (P less than .05) than that from liver. Relative incorporation of labeled C into skeletal muscle RNA (395.9 pmol/mmol) was greater (P less than .05) than for DNA (189.5 pmol/mmol). The same trend was observed for liver RNA (78.0 pmol/mmol) and DNA (55.6 pmol/mmol), but differences were nonsignificant. These data suggest that at least part of the high concentration of endogenous fructose measured in fetal pigs in utero is involved in synthesis of nucleic acids, thereby providing substrate for anabolic functions necessary for fetal growth and development.