Influence of first calving age and nutrition on the performance of early mated Nguni heifers

Abstract

The effect of early mating on the production and reproductive ability of Nguni heifers was investigated. One group (MN group) of heifers (n = 15) was stall-fed from  weaning and mated at approximately 13 months of age. The second group (CN  group) (n = 30) was reared on veld and fIrst mated at approximately 15 months of age. Calving percentages of 73.3 and 75.9 were achieved, while the weaning  percentages were found to be 66.7 and 69.0 for the two groups, respectively.  Reconception rates were 83.3 and 78.3% for the MN and CN groups, respectively. Body mass of the MN and CN heifers differed signifIcantly (P EO 0.01) only after calving (286.3 vs. 315.9 kg). Birth and weaning mass of calves did not differ signifIcantly between the two groups. Cow efficiency indices were significantly (P EO 0.05) higher in the MN group compared to the CN group (2.4 vs. 2.0). It was concluded that, even with a restricted mating period of 42 days, Nguni heifers could be successfully mated at the age of 13 to 15 months. No dystocia problems were experienced.

Die invloed van vroee paring op die produksie- en reproduksieprestasie van Nguni-verse is ondersoek. Een groep (MN-groep) verse (n = 15) is 011 speen in die stal gevoer en op ongeveer 13 maande gepaar. Die tweede groep (CN-verse) (n = 30) is op die veld gehou en op ongeveer 15 maande vir die eerste maal gepaar.
Kalfpersentasies van onderskeidelik 73.3 en 75.9 is verkry, terwyl  speenpersentasies onderskeidelik 66.7 en 69.0 vir die twee groepe was.   Herbesetting was 83.3 en 78.3% vir die MN- en CN-groepe, onderskeidelik. Liggaamsmassa van die MN- en CN-verse het slegs na kalwing betekenisvol (P EO 0.01) van mekaar verskil (286.3 vs. 315.9 kg). Geboorte- en speenmassas van die kalwers het nie betekenisvol tussen die twee groepe verskil nie.   Koeidoeltreffendheidsindekse was betekenisvol (P EO 0.05) hoer in die MN-groep vergeleke met die CN-groep (2.4 vs. 2.0). Daar is tot die gevolgtrekking gekom dat Nguni-verse selfs met 'n beperkte dekperiode van 42 dae suksesvol op  ouderdomme 13 tot 15 maande gepaar kan word. Geen distokia probleme is  ondervind nie.