Index Selection and Feed Intake Restriction in Swine. II. Effect on Energy Utilization

Abstract

SummaryFifty-three index select and control line barrows were randomly assigned to three feeding levels at 83 d of age. They were slaughtered at approximately 188 d of age to determine the effects of index selection (for increased average daily gain and decreased backfat) and level of feed intake on energy utilization. During the trial, the feed intake levels were twice daily to appetite (AP), once daily feeding of 91% of appetite (AP91) or once daily feeding of 82% of appetite (AP82) intake. The metabolizable energy intake required per kilogram of edible lean deposited (Mcal/kg) was reduced (P<.05) by restricting intake and was lower (P<.01) for index than for control barrows [index: 25.6 (AP), 23.3 (AP91) and 25.3 (AP82) vs control: 31.1 (AP), 27.5 (AP91) and 28.1 (AP82)]. However, intake restriction and index selection increased (P<.05) the energy lost per unit of retained energy (index: 1.33, 1.45 and 1.53 vs control: 1.24, 1.29 and 1.34). The index line had a higher (P<.05) maintenance requirement than the control line when expressed'unit of weight (kg'TS) -1" day -I, but the difference was less when expressed'unit of lean (kg'S3)-l'day -I. The energy cost of protein deposition varied from 9.02 to 11.25 kcal/g, while the energy cost of fat deposition ranged from 12.73 to 12.86 kcal/g. Variation among animals in metabolizable energy intake was explained by variation in lean mass maintained and the quantity of prOtein and fat deposited.

The effects of ad libitum and restricted feeding on Yorkshire pigs selected for reduced residual feed intake

“…This indicates that the Select line is partitioning less of the consumed energy for maintenance requirements than the Control line. These results, however, disagree with the findings from (Cleveland et al, 1983), who found that leaner pigs partition more of their metabolizable energy for maintenance relative to fat pigs. In the current study, the Select line was leaner than the…”

Relationships among performance, residual feed intake, and product quality of progeny from Red Angus sires divergent for maintenance energy EPD1

“…It has been estimated that maintenance functions account for 70 to 75% of total energy expenditure in the producing female and anywhere from 35 to 50% in growing and fi nishing animals (Ferrell, 1988). Studies have indicated that variation in ME M requirements can be partially explained by the variation in body composition (i.e., lean and fat tissue) and associated metabolic processes (Ferrell et al, 1979;Cleveland et al, 1983). Other contributors to the ME M requirement of an animal are body tissues (i.e., visceral organs) with high metabolic activity, particularly the liver and digestive tract.…”

Selection for components of efficient lean growth rate in pigs 4. Genetic and phenotypic parameter estimates and correlated responses in performance test traits with ad-libitum feeding

“…Sather and Fredeen (1978), Vangen (1979 and1980) and Cleveland et al (1982), Cleveland, Johnson, Mandigo and Peo (1983) selected on lean growth indices, essentially equal to growth rate minus backfat depth, expressed in phenotypic standard deviation units, and reported increased growth rate with reductions in backfat and FCR. Sather and Fredeen (1978), Vangen (1979 and1980) and Cleveland et al (1982), Cleveland, Johnson, Mandigo and Peo (1983) selected on lean growth indices, essentially equal to growth rate minus backfat depth, expressed in phenotypic standard deviation units, and reported increased growth rate with reductions in backfat and FCR.…”