Abstract
The purpose of this study was to evaluate the effect of geographical regions of South Africa on the inter-calving period of Nguni cows. Data of Nguni cows (n = 26 681) from 427 Nguni breeders in the Savannah and the Grassland Biomes were statistically analyzed to establish the impact of non-genetic factors on the inter-calving period (ICP) of these cows. Cows with an ICP of less than 315 and above 730 days were removed from the dataset before analysis, to comply with Nguni breed standards. Dam age was included as a covariant. The ICP increased slightly up to 48 months of age, after which a decline was noticed up to the age of 108 months. Cows in the Savannah Biome had a shorter ICP than those studied in the Grassland Biome. Within the Savannah Biome, the ICP of cows was significantly shorter in the Eastern Kalahari Bushveld bioregion than in any other bioregion, while in the Grassland Biome the ICP was significantly shorter for cows calving in the Drakensberg and the Dry Highveld bioregions. In terms of seasons, the ICP of cows bred in spring and summer was significantly shorter than that of cows bred in autumn and winter. Categorization of cows in year groupings indicates significant year effects. Keywords : Biome, bioregion, dam age, reproduction, season
Highlights
The reproductive efficiency of cows is a key factor in the increase in numbers of any beef herd (Ladermann & Schoeman, 1994)
Nguni breeders from the Savannah Biome constituted 57% of the data, while 28.8% of the Nguni breeders were located in the Grassland Biome
The observation is that a longer inter-calving period (ICP) plays a role in reducing the number of cows in production, since such cows will eventually be culled from the herd
Summary
The reproductive efficiency of cows is a key factor in the increase in numbers of any beef herd (Ladermann & Schoeman, 1994). One of the factors that is related to cow productivity is the inter-calving period (ICP), which is defined as the time period from one calving to the next. One of the factors that is related to cow productivity is the inter-calving period (ICP), which is defined as the time period from one calving to the It has been described as a measure that involves three phases, namely the gestation period, postpartum anestrus, and the subsequent breeding period. The postpartum period is the most critical of the three phases to ensure that the ICP is within the target range of less than 400 days on average for the herd if a cow is to calve every year. The ICP is a major factor in the determination of the reproductive efficiency of a cow and it is affected, among others, by the availability and management of nutrition (Mukasa-Mugerwa, 1989)
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