The influence of proportion of Hereford breeding in a multibreed synthetic beef cattle population on birth weight and weaning weight

(South African J of Animal Science, 2000, 30, Supplement 1: 124-126

Pre-weaning growth traits of the Hereford breed in a multibreed composite beef cattle population

Data from a multibreed composite beef cattle population, managed under intensive irrigated grazing conditions,were used to estimate direct additive heritabilities (h2a), maternal heritabilities (h2m) and maternal permanent environmental effects (c2) for birth weight (BW) and weaning weight (WW) of the calf and cow efficiency of the dam (CE: WW/dam weight0.75 x 100). Calves born between 1968 and 1993 (n = 52628) had varying levels of Hereford genes, ranging from 0% to 100%, with an average of 19.3%. Direct heritabilities, fitting unitrait models, were 0.72, 0.54 and 0.19 for BW, WW and CE, respectively, with corresponding estimates of maternal heritabilities being 0.14, 0.21 and 0.42. Genetic correlations between direct and maternal effects (ram) were negative for all three traits, varying from -0.40 to -0.65. Maternal permanent environmental effects were 0.06, 0.12 and 0.11 for BW, WW and CE, respectively. Direct breeding values and maternal breeding values for BW and WW decreased with increasing proportion of Hereford. Direct breeding value for CE increased, while maternal breeding value for CE reached a minimum value at 0.62 proportion of Hereford. (South African Journal of Animal Science, 2000, 30(3): 220-229

Estimates of crossbreeding parameters in a multibreed beef cattle crossbreeding project

Data from purebred and crossbred cattle, consisting of the Afrikaner (A), Simmentaler (S) and Hereford (H) breeds managed in a relatively intensive but high stocking rate environment, were analysed to estimate breed direct effects, individual heterotic effects, breed maternal and maternal heterotic effects for birth weight (BW) and weaning weight (WW). Simmentaler breed direct effects, expressed as deviation from the general mean, were positive (P 0.05) for WW. Individual heterotic effects for BW were significant (P 0.05) for both BW and WW. (South African Journal of Animal Science, 2000, 30(3): 193-203

The influence of proportion of Simmentaler breeding in a multibreed beef cattle population on preweaning growth traits.

AgriwetenskappeVeekundige WetenskappePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Describing gonad development and gametogenesis in southern Africa’s endemic box jellyfish Carybdea branchi (Cubozoa, Carybdeidae)

Information on the reproductive development of species of box jellyfish (class Cubozoa) is poor globally, despite their significance as potent stingers and worrying projections about range expansions. While most species are confined to tropical and subtropical waters, the South African box jellyfish Carybdea branchi is commonly found in the cold-water (especially southern) Benguela ecosystem. Its biology is unknown. Here, we examine reproductive development and describe gametogenesis in this dioecious species. Four and five maturity classes were determined for males and females, respectively, as well as five oocyte developmental stages. Oocyte sizes differed significantly between developmental stages. Mature and immature medusae differed significantly in size, but males and females did not. Individuals matured at approximately 30 mm average bell dimensions. Carybdea branchi displayed gonadal development characteristic of a semelparous organism.Keywords: Benguela ecosystem, gonad, histology, maturity classification, oog enesis, reprodu ct ive deve l opment , spermat og enesi

The influence of proportion of Simmentaler breeding in a multibreed synthetic beef cattle population on preweaning growth traits

Data from a multibreed composite beef cattle population managed under intensive irrigated grazing conditions were used to estimate direct additive heritabilities (h2a) and maternal heritabilities (h2m) for birth weight (BW) and weaning weight (WW) of the calf and cow efficiency of the dam (CE; WW/dam weight0.75). Calves born between 1968 and 1993 (n = 52 628) had varying levels of Simmentaler genes, ranging from 0% to 97%, with an average of 33.4%. Direct heritabilities fitting unitrait models were 0.66, 0.53 and 0.21 for BW, WW and CE respectively, with corresponding estimates of h2m being 0.22, 0.36 and 0.59. Genetic correlations between direct and maternal effects (ram) were negative for all three traits, varying from -0.32 to -0.63. Direct breeding values for BW and WW decreased and maternal breeding values increased with increasing proportion of Simmentaler. Cow efficiency was unaffected by an increase in the proportion of Simmentaler.Articl

Estimates of crossbreeding parameters in a multibreed beef cattle crossbreeding project.

AgriwetenskappeVeekundige WetenskappePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Pre-weaning growth traits of the Hereford breed in a multibreed composite beef cattle population

Data from a multibreed composite beef cattle population, managed under intensive irrigated grazing conditions, were used to estimate direct additive heritabilities (h2a), maternal heritabilities (h2m) and maternal permanent environmental effects (c2) for birth weight (BW) and weaning weight (WW) of the calf and cow efficiency of the dam (CE: WW/dam weight0.75 x 100). Calves born between 1968 and 1993 (n = 52628) had varying levels of Hereford genes, ranging from 0% to 100%, with an average of 19.3%. Direct heritabilities, fitting unitrait models, were 0.72, 0.54 and 0.19 for BW, WW and CE, respectively, with corresponding estimates of maternal heritabilities being 0.14, 0.21 and 0.42. Genetic correlations between direct and maternal effects (ram) were negative for all three traits, varying from -0.40 to -0.65. Maternal permanent environmental effects were 0.06, 0.12 and 0.11 for BW, WW and CE, respectively. Direct breeding values and maternal breeding values for BW and WW decreased with increasing proportion of Hereford. Direct breeding value for CE increased, while maternal breeding value for CE reached a minimum value at 0.62 proportion of Hereford.Articl

ross-shelf movement of Chrysaora fulgida (Scyphozoa; Discomedusae) off Namibia inferred from stable isotopes (δ15N and δ13C)

Large and small specimens of two species of metagenic Scyphozoa (true jellyfishes) can be found in nearshore waters off central Namibia throughout the year. Whereas populations of Chrysaora africana are largely restricted to inshore waters, C. fulgida occurs across the shelf, with small individuals found inshore and large individuals primarily found offshore. We examined stable isotopes δ15N and δ13C of both species in Walvis Bay and found that large-sized C. fulgida have lower δ15N values than small individuals and C. africana throughout the year. These differences are interpreted to reflect cross-shelf changes in δ15N baseline levels, with greater nitrogen recycling (and hence lower δ15N values) occurring offshore. The occasional/seasonal nearshore appearance of large C. fulgida with low δ15N values therefore implies routine, onshore advection. The values of δ13C did not show cross-shelf differences, which suggests that jellyfish populations across the shelf are supported by phytoplankton-based food chains. This study emphasises the value of using stable isotopes to examine the mesoscale structuring of jellyfish populations. Keywords: Chrysaora africana, coastal upwelling, eastern boundary currents, energy flow, jellyfish, metagenesis, molecular marker

There are three species of Chrysaora (Scyphozoa: Discomedusae) in the Benguela upwelling ecosystem, not two

Ras, V., Neethling, S., Engelbrecht, A., Morandini, A.C., Bayha, K.M., Skrypzeck, H., Gibbons, M.J. (2020): There are three species of Chrysaora (Scyphozoa: Discomedusae) in the Benguela upwelling ecosystem, not two. Zootaxa 4778 (3): 401-438, DOI: https://doi.org/10.11646/zootaxa.4778.3.