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"Experientia docet" - Experience is the best teacher

The heritability of acceptability in South African Merino sheep

  • 2001
  • Issue: 1
  • Volume: 31
G.J. Erasmus, F.W.C. Neser , J.B. van Wyk and J.J. Olivier Page: 13 - 14

Selection for production and reproduction in South African Merino sheep is always combined with selection based on visual appraisal and will, in all probability, remain so for many years to come. Heritabilities for acceptability were estimated using a threshold model…

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Heritability estimates derived from threshold analyses for reproduction and stayability traits in a beef cattle herd

  • 2001
  • Issue: 1
  • Volume: 31
R.R. van der Westhuizen, S.J. Schoeman, G.F. Jordaan and J.B. van Wyk Page: 25 - 32

The object of this study was to estimate heritabilities and sire breeding values for stayability and reproductive traits in a composite multibreed beef cattle herd using a threshold model. A GFCAT set of programmes was used to analyse reproductive data.…

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Genetic parameters for reproductive traits in a beef cattle herd estimated using multitrait analysis

  • 2001
  • Issue: 1
  • Volume: 31
R.R. van der Westhuizen, S.J. Schoeman, G.F. Jordaan and J.B. van Wyk Page: 41 - 48

The object of this study was to estimate heritabilities and genetic correlations for reproductive traits in a composite multibreed beef cattle herd using multitrait analysis. A REML procedure fitting a multitrait animal model was used to analyse data. Heritabilities and…

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Selected mineral and heavy metal concentrations in blood and tissues of vultures in different regions of South Africa

  • 2001
  • Issue: 2
  • Volume: 31
E. van Wyk, F.H. van der Bank, G.H. Verdoorn and D. Hofmann Page: 57 - 63

Concentrations of eight essential elements (Ca, Co, Cr, Cu, Fe, Mn, Ni and Zn) and three toxic metals (Al, Pb and Sr) were measured in various tissue samples from African whitebacked (Pseudogyps africanus), Cape griffon (Gyps coprotheres) and Lappetfaced (Torgos…

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An evaluation of Panicum maximum cv. Gatton: 1. The effect of stocking rate and period of absence on the production of sheep

  • 2001
  • Issue: 2
  • Volume: 31
E.A. Relling, W.A. van Niekerk, R.J. Coertze and N.F.G. Rethman Page: 77 - 83

The aim of this study was to evaluate the livestock production potential of Panicum maximum cv. Gatton cultivated under dry-land conditions and grazed at various stocking rates after various periods of re-growth. Treatments included a high stocking rate, fast rotation…

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An evaluation of Panicum maximum cv. Gatton: 3. The partial digestion by sheep of organic matter, nitrogen and neutral detergent

  • 2001
  • Issue: 2
  • Volume: 31
E.A. Relling, W.A. van Niekerk, R.J. Coertze and N.F.G. Rethman Page: 93 - 99

The aim of this study was to quantify the partial digestion of organic matter (OM), nitrogen (N) and neutral detergent fibre (NDF) in sheep grazing Panicum maximum cv. Gatton pastures at three stages of pasture maturity during summer, autumn or…

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The effect of flavophospholipol (Flavomycin ®) on milk production and milk urea nitrogen concentrations of grazing dairy cows

  • 2001
  • Issue: 2
  • Volume: 31
B.J. van der Merwe, T.J. Dugmore and K.P. Walsh Page: 101 - 106

Milk production and milk composition responses to supplementation of Holstein-Friesian cows grazing kikuyu pasture in summer and a combination of annual ryegrass and maize silage in winter with 64 mg/d flavophospholipol were determined. There was no difference in the average…

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The effect of selection on genetic parameter estimates

  • 2001
  • Issue: 2
  • Volume: 31
R. van Dyk, F.W.C. Neser and F.H. Kanfer Page: 107 - 114

A simulation study was carried out to investigate the effect of selection on the estimation of genetic parameters for butterfat production in dairy cattle. It was found that selection leads to a substantial overestimation of fixed effects and variance components…

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Intake and rumen degradation in cattle fed napier grass (Pennisetum purpureum) supplemented with various levels of Desmodium int

  • 2001
  • Issue: 3
  • Volume: 31
J.N. Kariuki, S. Tamminga, C.K. Gachuiri, G.K. Gitau and J.M.K. Muia Page: 149 - 157

This study was conducted to assess the effect of greenleaf desmodium (Desmodium intortum) and sweet potato vine (Ipomoea batatus) supplementation of napier grass on dry matter intake, degradation and rumen fermentation in Friesian steers. Four fistulated steers were offered napier…

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