Direct response to divergent selection for yearling growth rate in Angus cattle

Parnell, P.; Arthur, P. F.; Barlow, R

doi:10.1016/s0301-6226(97)00045-6

Cited by 29 publications

(30 citation statements)

References 12 publications

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“…The average level of inbreeding gradually increased with generation number and was slightly higher for the S lines reaching a level of 7.4% compared with 5.7% for the NS lines for calves born in 1997 (Figure 1). The rate of inbreeding across lines and environments was 0.2%/year or 1.2%/generation and is similar to estimates in the literature (0.07 to 0.3%/year or 0.3 to 1.3%/generation) (Baker et al, 1991;Koch et al, 1994;Parnell et al, 1997;Koch et al, 2004).…”

Section: Resultssupporting

confidence: 85%

“…This was reduced to 4.4 and 6.5 years respectively in the post-crossover phase. These are similar to the generation interval of 5.1 reported by Mercadante et al (2003) for a selection experiment with Nelore cattle in Brazil, but are in general higher than generation intervals reported in the literature of 2 to 4.3 years for sires and 4 to 6.6 years for dams (Baker et al, 1991;Koch et al, 1994;Parnell et al, 1997) and are primarily due to the late age at first mating of both sexes and longer retention of cows in the herd (Mercadante et al, 2003). The average level of inbreeding gradually increased with generation number and was slightly higher for the S lines reaching a level of 7.4% compared with 5.7% for the NS lines for calves born in 1997 (Figure 1).…”

Section: Resultssupporting

confidence: 83%

“…The yearly genetic trends for weaning weight, the primary selection trait, were lower than correlated trends reported in the literature (0.24 and 0.22 kg/year for the S and NS lines vs. 0.48 to 1.01 kg/year) (Baker et al, 1991;Arthur et al, 1997;Pereira et al, 2008), while the correlated yearly trends for yearling weight in the current study ( Figure 4) (Baker et al, 1991;Koch et al, 1994;Parnell et al, 1997;Razook et al, 1998;Mercadante et al, 2003;Koch et al, 2004;Pereira et al, 2008). The correlated selection response of BW in the NS line was twice that of calves in the S line and both estimates were within the range of literature estimates (0.04 and 0.07 kg/year for the S and NS lines vs. -0.06 to 0.25 kg/year) (Baker et al, 1991;MacNeil et al, 1992;Arthur et al, 1997;Pereira et al, 2008).…”

Section: Resultscontrasting

confidence: 82%

“…Selection experiments in beef cattle have been mainly concerned with improvements in growth traits, with published reports of 1.8 to 6.3 generations of selection (Mrode, 1988b;Baker et al, 1991;Koch et al, 1994;Parnell et al, 1997;Razook et al, 1998;Mercadante et al, 2003, Koch et al, 2004Pereira et al, 2008). However, Mrode (1988a) noted that many earlier experiments suffered from inadequate designs with respect to population size and levels of inbreeding.…”

Section: Introductionmentioning

confidence: 99%

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Long-term selection experiment with Afrikaner cattle 3. Selection applied and response in calf growth traits

2009

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________________________________________________________________________________ AbstractA selection and line x environment interaction study with grade Afrikaner cattle was established in 1956 at Matopos Research Station, Zimbabwe. Two selection lines of 100 cows each were reared in different management environments. The non-supplemented (NS) line relied on the range throughout the year and was mated to calve with the onset of the rains (December to February). The supplemented (S) line was offered protein-rich supplements during the dry season and mated to calve prior to the onset of the rains (October to December). In 1976, after approximately two generations of selection, lines were sub-divided into 75 cows each, where one sub-line remained within each environment as a control; the remaining sub-lines were interchanged between environments. Bulls were selected on weaning weight within control lines, while replacement heifers were selected on weight at mating within sub-line. Data recorded over approximately six generations of selection (40 years) were analyzed. The average age of sires and dams at the time of birth of their progeny was 5.9 and 7.5 years respectively in the pre-crossover phase and was reduced to 4.4 and 6.5 years respectively in the post-crossover phase. The rate of inbreeding across lines and environments was 1.2%/generation. The cumulative selection differential trends for both the S and NS lines for adjusted weaning weight plotted against generation number were very low, relatively linear and greater for the S line (0.10 s.d./year) compared with the NS line (0.08 s.d./year). Direct and correlated responses were uniformly low, approximating 1% of the trait mean per generation, and indicating that considerable attention was given to secondary characters. These results concur with general findings of effective direct and correlated responses of weight traits to individual selection. ________________________________________________________________________________

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 83%

Section: Resultscontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Long-term selection experiment with Afrikaner cattle 3. Selection applied and response in calf growth traits

2009

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“…There was a significant relationship between calpain activity (estimated as the µ-calpain:calpastatin ratio) immediately after death, and subsequent rate of change in myofibre release and shear force over a 9-day aging period (Table 2). In a separate study, using Angus cattle from lines divergently selected on the basis of average daily gain from birth to 1 year of age (Parnell et al 1997), it was found that selection for high yearling weight was associated with reduced muscle protein degradation (Oddy et al 1998), increased calpastatin concentration and reduced rate of post mortem tenderisation (McDonagh 1998). These results are consistent with Morris and Speck (1998) who also observed differences in calpain activity and meat toughness in Angus cattle selected for high rates of gain.…”

Section: Proteolysis and Aging Rate Of Meatmentioning

confidence: 99%

Nutritional and developmental effects on the intrinsic properties of muscles as they relate to the eating quality of beef

Oddy¹,

Harper²,

Greenwood³

et al. 2001

Aust. J. Exp. Agric.

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Abstract. The intrinsic properties (those extant at the time of slaughter) of bovine skeletal muscle as they relate to the subsequent quality attributes of beef are reviewed here. Attributes of bovine skeletal muscle that ultimately affect toughness, colour, fat content, flavour, juiciness, and nutritive value of beef are discussed. The dynamic nature of muscle development, particularly with regard to structure and composition, is highlighted. Variation in development of muscle structure and composition due to inherited (genetic) factors and environment (particularly nutrient supply) are described. Examples are given of the implications of sources of variation due to animal genotype, age, nutrient supply, and hormonal environment on muscle cellularity and growth, fibre type, connective tissue composition and structure as they affect meat quality attributes.Key intrinsic properties of muscle include muscle type, cellularity, size, myofibre type, connective tissue composition and structure, glycogen and fat content and proteolytic activity. Activity of the calpain system at slaughter is seen as an important attribute. Regulation of myofibrillar and connective tissue proteolysis in vivo are discussed together with implications for subsequent meat quality. Amongst the on-farm environmental factors, nutritional history and developmental pathway are identified as factors that can be responsible for significant variation in the intrinsic properties of muscle that contribute to variation in toughness, colour and fat content, and thus consumer liking of beef.

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Validation of Genome-Wide Association Studies (GWAS) Results

Henshall

2013

Methods in Molecular Biology

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Validation of the results of genome-wide association studies or genomic selection studies is an essential component of the experimental program. Validation allows users to quantify the benefit of applying gene tests or genomic prediction, relative to the costs of implementing the program. Further, if implemented, an appropriate weight in a selection index can only be derived if estimates of the accuracy of genomic predictions are available. In this chapter the reasons for validation are explored, and a range of commonly encountered scenarios described. General principles are stated, and options for performing validation discussed. Designs for validation are heavily dependent on the availability of phenotyped animals, and also on the pedigree structures that characterize the breeding program. Consequently, there is no single plan that is always applicable, and a custom plan often must be developed.

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Direct response to divergent selection for yearling growth rate in Angus cattle

Cited by 29 publications

References 12 publications

Long-term selection experiment with Afrikaner cattle 3. Selection applied and response in calf growth traits

Long-term selection experiment with Afrikaner cattle 3. Selection applied and response in calf growth traits

Nutritional and developmental effects on the intrinsic properties of muscles as they relate to the eating quality of beef

Validation of Genome-Wide Association Studies (GWAS) Results

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