Divergent selection on intramuscular fat in rabbits: Responses to selection and genetic parameters1

Abstract

A divergent selection experiment on intramuscular fat (IMF) was performed in rabbits. The aim of this study is to estimate the response to selection, the correlated responses in carcass and meat quality traits, and their genetic parameters. Selection criterion was the averaged phenotypic value of IMF measured at 9 wk of age in 2 full-sibs of the candidate. Traits considered were IMF, BW, chilled carcass weight, reference carcass weight, scapular and perirenal fat weights, carcass and meat color, pH, protein and fatty acid composition of meat. Total direct response to selection for IMF was 2.6 phenotypic SD of the trait, around 5% of the mean (1.09 g/100 g) per generation, with both lines following a symmetrical trend. Heritability of IMF was high (0.54), and in general, all traits related to carcass fat depots and IMF fatty acid composition showed high heritabilities (dissectible fat of the carcass, 0.70; MUFA percentage, 0.61; PUFA percentage, 0.45; and PUFA:SFA ratio, 0.42), except SFA percentage (0.09). The other carcass and meat quality traits showed moderate to low heritabilities. Intramuscular fat and dissectible fat percentage showed a low genetic correlation (0.34). Intramuscular fat was positively correlated with MUFA percentage (0.95) and negatively correlated with PUFA percentage (-0.89) and PUFA:SFA ratio (-0.98), corroborated with high correlated responses to selection. The rest of the traits did not show any substantial correlated response except protein content, which was greater in the high-IMF line than in the low-IMF line.

Contributions on the Sensorial, Physico-Chemical and Nutritional Characterization of Meat in Flemish Giant Rabbit Breed

“…The differences were not significant statistically (table 5). The achieved values were places within the limits obtained by other authors on rabbit meat of average sized breeds, from 69.7 g/100 g in limbs muscles [10,11,[41][42][43]. The pH values found were close to those analyzed in average sized breeds [43] in LD muscles and lower than those, in SM muscles.…”

“…Slightly lower values have been reported by other authors for average sized rabbit breed, while the age at slaughter was much lower (approximately three months) [40][41][42][43][50][51][52][53][54][55].…”

“…The rabbit represents a good model for biological studies due to the short interval between generations and to the low cost of producing their carcasses [41][42][43][44][53][54][55]. Aspects regarding the quality of rabbit meat are being studied intensively at the level of average size breeds [1-3, 6-66] but for the Flemish giant breed (which can be used as an improver of the meat yield in other breeds) insufficient data has been reported.…”

Effect of selection for intramuscular fat on the fatty acid composition of rabbit meat

“…Normally, the first parity was used to collect the IMF data and the second parity to provide the rabbits for next generation, although exceptionally some IMF measurements were made on the second or third parity. More details of this experiment can be found in Martínez-Álvaro et al (2016a). A total of 2 713 rabbits were considered in the pedigree file, from which 1 511 were evaluated.…”

Effect of Divergent Selection for Intramuscular Fat Content on Muscle Lipid Metabolism in Chickens

“…Based on its heritability and adequate variability, it is possible to increase the IMF content through genetic selection. IMF selection programs have been performed in many livestock, including pigs [5], cattle [6], chickens [7,8], and rabbits [9]. In chickens, some divergent selection lines for highly heritable traits have been successfully bred, such as for body weight [10], abdominal fat [11,12], and the ultimate pH of the pectoralis major muscle [13].…”