Submitted to: Animal Science Progress Report
Publication Type: Other
Publication Acceptance Date: 8/3/1998
Publication Date: N/A
Technical Abstract: Addition of spray-dried plasma protein (PP) to early growing pig diets results in increased food intake and faster growth. It is unknown if the increased growth is due mainly to increased feed intake or is mediated through other physiological mechanisms affected by PP. At 14 d of age, 26 barrows were fitted with gastric cannuli and randomly assigned within a 2 X X3 factorial experimental design, including treatments of 0% PP or 7% PP an feeding levels of 80%, 100%, or 120% of normal feed intake. Pigs were fed through gastric cannuli every 2 h from 10 a.m. to 10 p.m. for 11 d, then sacrificed for tissue collection. Blood samples were drawn on d 2,5,8, and 11, and body weight (BW) was recorded daily. An effect of feeding level was found in BW over time, d 11 BW, and average daily gain (ADG). All of these endpoints were lower in the 80% feed intake groups than in the 100% or 120% feed intake groups. No effect of PP on weight gain was observed. Leptin, adipose IGF-I and liver IGF-I mRNA expression did not differ between either intake or PP levels. Serum growth hormone (GH) concentrations did not differ over time, intake level, or PP level. Serum IGF-I concentrations were correlated with ADG across treatments, as was adipose IGF-I mRNA expression with ADG. Leptin RNA expression was correlated with ADG only at the 100% feeding level. Serum insulin, hypothalamic IGF-I mRNA and hypothalamic neuropeptide Y mRNA levels were all decreased in PP-treated pigs relative to controls at d 11. These data suggest that, when feed intake is controlled, plasma protein does not affect growth or peripheral endocrine parameters in young pigs, but may be acting on appetite-controlling pathways.