Factors influencing recalving rate in lactating beef cows in the sweet dry bushveld of northern Transvaal

Abstract

Factors influencing the recalving rate of 2165 lactating beef cows of four pure breeds (Afrikaner, Hereford, Bonsmara and Simmentaler) and three cross-bred types were investigated on the Mara Research Station between 1972 and 1982. Average recalving rate was 88.3%. The influence of year, breeding  group, cow age, date of calving and body mass at four stages was investigated. Recalving rate differed significantly (P < 0.05) between years varying ftom 76.2 to 92.5%, but significant year x breeding group (P < 0.01) and breeding group x date of calving (P < 0.05) interactions were also indicated. Body mass wils unimportant (P > 0.05) as a predictor of recalving rate. However, cows with average body mass were more inclined to recalve than those with extreme body masses.

Faktorew at die herkalwing van 2165 lakterendev leisraskoeiev an vier suiwer rasse (Afrikaner, Hereford, Bonsmara en Simmentaler) en drie kruisrastipes beinvloed het, is tussen 1972 en 1982 op die Mara Navorsingstasie ondersoek. Die gemiddelde herkalwingspersentasie was 88.3%. Die invloed van jaar, teelgroep, koeiouderdom, kalwingsdatum en liggaamsmassa op vier stadia geneem, is ondersoek. Herkalwingspersentashiee t slegsb etekenisvol (P < 0.05) tussen jare verskil en het tussen 76.2 en 92.5% gevarieer. Betekenisvolle interaksies vir jaar X teelgroep (P < 0.01) en teelgroep X datum van kalwing (P < 0.05) is ook aangetoon, terwyl liggaamsmassa 'n onbelangrike (P > 0.05) voorspellerv an herkalwing was. Liggaamsmassavsa n koeie wat nie herbeset is nie, het egter meer gevarieer as die wat wel beset geraak het. Koeie met gemiddelde massa was egter meer geneig om te herkalf as die met uiterste massas.

Keywords: Beef cattle, body mass, calving age, recalving