Responses in carcass composition to divergent selection for components of efficient lean growth rate in pigs

Cameron, N. D.; Curran, M. K.

doi:10.1017/s1357729800013904

Cited by 31 publications

(14 citation statements)

References 27 publications

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“…This resulted from the highly favourable genetic correlations of growth rate with ultrasonic backfat (UBF), food conversion ratio (TFC), carcass weight daily gain (CDG), carcass fat (CFT) and lean percentage (LEAN). The achieved responses here were comparable with increases of 12.6 to 25.4 g/d for TDG, and decreases of −0.46 to −0.70 mm for UBF and −0.05 unit for TFC per generation of selection for a more sophisticated selection criterion (lean growth rate), with pigs also tested on restricted feeding [2,21]. Literature reports of phenotypic changes in backfat in response to selection for increased growth rate in pigs fed ad libitum were either favourable [8] or unfavourable [16,26].…”

Section: Direct and Correlated Responsessupporting

confidence: 64%

Genetic parameters and responses of performance and body composition traits in pigs selected for high and low growth rate on a fixed ration over a set time

Nguyen

McPhee

2005

Genet. Sel. Evol.

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-Two lines of Large White pigs of common genetic origin were divergently selected over four years for high and low growth rate during a 6 week post-weaning test period in which all pigs were fed the same total amount of food (80% of estimated ad libitum intake). Genetic parameters and direct and correlated responses in performance and carcass traits were estimated on 2884 pigs with pedigrees comprising a total of 5324 animals, with restricted maximum likelihood and best linear unbiased prediction methods applied to a multi-trait animal model. Estimates of heritability (±SE) were 0.19 ± 0.04 for lifetime daily gain (LDG), 0.16 ± 0.03 for test daily gain (TDG), 0.25 ± 0.04 for ultrasound P2 backfat (UBF) and 0.16 ± 0.03 for food conversion ratio during test (TFC), and 0.15 ± 0.04 for daily carcass weight gain (CDG), 0.43 ± 0.06 for carcass backfat (CFT) and 0.40 ± 0.06 for carcass lean percentage (LEAN). Common litter effects for TDG, UBF and TFC were less than 5% and for LDG, 17% of total phenotypic variance. Genetic correlations between performance and carcass traits were moderately to highly favourable. After four years of divergent selection for growth rate, the selection responses in estimated breeding value (EBV) for TDG were 40.14 and -41.11 g (SED 2.95) for the high and low growth lines, respectively. The regressions of EBV on year of birth, indicate that the annual genetic trend for TDG, was 8.73 g/yr in the high and -8.48 g/yr in the low lines (P < 0.001). Correlated genetic responses in the high and low lines respectively were 5.28 g and -12.40 g (SED 2.09) in LDG, -0.35 mm and 0.56 mm (SED 0.009) in UBF, -0.145 units and 0.185 units (SED 0.012) in TFC, 3.17 g and -10.97 g (SED 1.53) in CDG, -1.13 mm and 1.01 mm (SED 0.155) in CFT and 1.24% and -1.27% (SED 0.150) in LEAN. It was concluded that selection for increased post-weaning daily gain on a ration of fixed amount reduces the age at slaughter and the level of backfat and increases the efficiency of food utilisation, weight and leanness of pig carcasses. divergent selection / pig / growth / restricted feeding / genetic responses

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Section: Direct and Correlated Responsessupporting

confidence: 64%

Genetic parameters and responses of performance and body composition traits in pigs selected for high and low growth rate on a fixed ration over a set time

Nguyen

McPhee

2005

Genet. Sel. Evol.

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“…The Select line of pigs exhibited a documented increase in lean growth efficiency, decreased backfat, and increased percentage of lean cuts in the pork carcass when compared with the Control line. This type of improvement has been observed with selection for lean growth rate (Cameron and Curran, 1995). Although significant improvements in feed efficiency and carcass composition have been realized in these pigs, meat quality has significantly declined.…”

Section: Discussionmentioning

confidence: 78%

Selection for lean growth efficiency in Duroc pigs influences pork quality.

Lonergan

Huff-Lonergan

Rowe

et al. 2001

Journal of Animal Science

201

127

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A unique line of Duroc pigs was established by intensive selection for increased lean growth efficiency. The objective of this study was to determine the influence of this selection strategy on fresh pork quality traits. Two lines of Duroc pigs originating from the same foundation herd were evaluated. One line was selected for lean growth efficiency over five generations (Select line), and the other was a contemporary line maintained from the foundation herd (Control line). All pigs in the trial tested negative for the halothane gene. Selection for lean growth efficiency resulted in improved lean gain, carcass lean, increased loin eye area, and less overall carcass fat. The Select line had significantly lower subjective firmness scores in longissimus and significantly greater amounts of moisture and protein lost as measurable drip in longissimus, semimembranosus, and semitendinosus. There were no differences in subjective color scores or in Hunter L, a, and b values between lines. No selection line differences were observed in glycolytic potential or ultimate pH. The longissimus and the semitendinosus exhibited significantly lower early postmortem pH values in Select line pigs. WarnerBratzler shear values were higher for Select line longissimus chops. Degradation of troponin-T was decreased in the Select line longissimus samples. This result suggests that reduced degradation of myofibrillar proteins may be associated with increased moisture and protein lost during storage. This research points out that elimination of the halothane gene will solve some but not all of the genetically influenced pork quality problems faced by the industry. The Select line of pigs appears to be more prone to producing pork that is soft and exudative, indicating a link between soft and exudative pork and some genetic selection strategies may exist. Therefore, it appears that selection for some economically important traits, such as feed efficiency or increased lean growth in the absence of the halothane gene, may compromise pork quality. ABSTRACT: A unique line of Duroc pigs was established by intensive selection for increased lean growth efficiency. The objective of this study was to determine the influence of this selection strategy on fresh pork quality traits. Two lines of Duroc pigs originating from the same foundation herd were evaluated. One line was selected for lean growth efficiency over five generations (Select line), and the other was a contemporary line maintained from the foundation herd (Control line). All pigs in the trial tested negative for the halothane gene. Selection for lean growth efficiency resulted in improved lean gain, carcass lean, increased loin eye area, and less overall carcass fat. The Select line had significantly lower subjective firmness scores in longissimus and significantly greater amounts of moisture and protein lost as measurable drip in longissimus, semimembranosus, and semitendinosus. There were no differences in subjective color scores or in Hunter L, a, and b values between lines. N...

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“…LGS lines were compared on ad libitum feeding, no change in food intake accompanied the selection responses in growth rate in the LGS lines (Cameron and Curran, 1995). On the other hand, in the DFI, LGA and LFC lines, performance tested and selected on ad libitum feeding, changes in food intake did occur and these may have contributed to responses in the selection criteria through changes in nutrient supply.…”

Section: Discussionmentioning

confidence: 94%

Peri-partum posture and behaviour of gilts and the location of their piglets in lines selected for components of efficient lean growth

McPhee¹,

Kerr²,

Cameron

2001

Applied Animal Behaviour Science

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The proportions of time that gilts expressed defined posture and behaviour traits and the locations of their piglets were determined from video recordings of observations made at 5 min intervals in the period extending from 2 hr pre-farrowing to 2 hr post-farrowing. The 137 gilts studied were from four pairs of Large White lines which had responded to divergent (high and low) selection for either daily food intake (DFI), lean food conversion efficiency (LFC), lean growth rate on ad libitum feeding (LGA) or lean growth rate on restricted feeding (LGS). LGS gilts again lay on their sides more often than low LGS gilts (0.96 v. 0.80) and were upright less often (0.04 v. 0.20). High LGS gilts changed posture less often than low LGS gilts (0.05 v. 0.31) but were more alert (0.79 v. 0.61). High LGS piglets were seen less at their mother's head, back and vulva or at the creep than low LGS piglets (0.06 v. 0.15). There were no differences between lines post-farrowing, almost all gilts lying on their sides with their piglets at the udder. Divergent selection for components of efficient lean growth rate on ad libitum feeding was not associated with changes in gilt behaviour and posture or in piglet location but selection for high lean growth on restricted feeding appeared to reduce the gilt's physical activity around farrowing with possible benefits for her welfare and that of her piglets.Keywords: Gilts; Lean growth; Farrowing behaviour; Piglet-location; Selection 2 IntroductionInterest has been raised over possible changes in the behaviour of livestock selected for high genetic merit for production traits which could affect their ability to thrive in intensive production environments (Mills, Beilharz and Hocking, 1997). If artificial farrowing environments fail to satisfy the welfare needs of the peri-parturient sow of these modern genotypes, reproductive traits could be adversely affected leading to economic loss. Studies of pig genotypes for behavioural differences of sows around farrowing have usually compared breeds which differ markedly in performance of production traits, such as efficiency of lean growth, and litter productivity. Typical studies are those of Meunier-Salaün et al., (1991), Wattanakul et al., (1997 and Sinclair et al., (1998), with Large White and Meishan or Meishan synthetic pigs. The specific behavioural traits examined in these studies reflect the welfare of the sow and her piglets and have also been used widely to test modifications to artificial farrowing environments (e.g. straw versus no straw by Cronin and Smith, 1992). One deficiency in the breed comparisons of peri-parturient behaviour of sows is that they generally lack a clear definition of the development processes which have led to the genetic differences in productivity between the breeds.Selection for different components of efficient lean growth rate has generated a set of well-defined genetic lines (Cameron, 1994). This study examines if the different selection strategies in these lines have affected the postures and beha...

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Responses in carcass composition to divergent selection for components of efficient lean growth rate in pigs

Cited by 31 publications

References 27 publications

Genetic parameters and responses of performance and body composition traits in pigs selected for high and low growth rate on a fixed ration over a set time

Genetic parameters and responses of performance and body composition traits in pigs selected for high and low growth rate on a fixed ration over a set time

Selection for lean growth efficiency in Duroc pigs influences pork quality.

Peri-partum posture and behaviour of gilts and the location of their piglets in lines selected for components of efficient lean growth

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