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

Abstract

________________________________________________________________________________ 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. ________________________________________________________________________________

Population structure and genetic trends for indigenous African beef cattle breeds in South Africa

“…Similar values have been reported for the Afrikaner breed by Beffa et al (2009) (4.4 for males and 6.5 females) and Pienaar et al (2015) with an average of 6.6 years. These estimates of generation intervals are slightly longer compared with the reported generation interval of 5.6 and 5.2 years for the Bonsmara, a local composite breed in South Africa (Groeneveld et al, 2009).…”

“…In South Africa, indigenous cattle breeds such as the Afrikaner, Drakensberger and Nguni breeds have made major contributions to livestock production because of their ability to adapt and produce in different systems (Muchenje et al, 2008;Beffa et al, 2009;Matjuda et al, 2014 ). The Afrikaner, Drakensberger, Nguni and Tuli cattle breeds have a long history of participation in animal recording and have an average complete pedigree recording in the first generation varying from 88.5% for the Nguni to 92.5% for the Afrikaner (Table 2).…”

Capitalizing on the Potential of South African Indigenous Beef Cattle Breeds: A Review

“…Production performance at Mara Research Station (semiarid subtropics); pure and crossbred performance Bonsmara, Afrikaner, Hereford, Simmentaler [48,49] Variance components and heritability estimates for growth traits, maternal traits Nguni [50,51] Breed performance in developing areas Nguni, Afrikaner, Bonsmara [52] Production and product traits tested under intensive feeding conditions Bonsmara and Nguni [53] Long-term selection experiment-genetic parameters and genotype X environment for calf growth traits Afrikaner [54] Comparison of meat quality traits between Sanga, Sanga-derived and Brahman cattle Nguni, Tuli, Nguni, Drakensberger, Bonsmara and Brahman [55,56] Population structure and genetic trends Afrikaner, Drakensberger, Nguni and Tuli and Boran [47] Genetic relationships between weaning weight and milk yield Nguni and Bonsmara [57] Coat traits associated with tick counts; genetic parameters for tick counts and resistance Nguni, Afrikaner, Bonsmara and Drakensberger [58][59][60] Effect of bioregion and environmental factors on cow size and reproduction Bonsmara [61] Morphology and physiology of claw quality Bonsmara [62] These breeds are well-established in the developed sector and make a major contribution to beef production and food security in South Africa. The implementation of selection programs in the developing sector, however, is facing multiple challenges particularly because there is often a lack of phenotypic (i.e., performance) and pedigree data.…”