Dairy R&D in SA

Discipline: calf rearing; Keywords: once or twice a day milk feeding, labour costs, health, mortality, rumen development.

Discipline: feeding; Keywords: concentrate feeding, milk yield, stocking rate, replacement, diminishing returns, gross margin.

Discipline: management; Keywords: KPI’s, TMR, breakeven milk yield, reproduction parameters, margin above feed costs.  

Discipline: environment; Keywords: GHG, nitrogen use efficiency, phosphorus, mixed pastures, soil health.

This is a summary of results reported by Dr Craig Galloway (see reference below) of farms where there have been improvements in the carbon balance and other parameters as indicated by data collected between 2013 and 2019. Some of the farms have data for all the years, whereas others only have data for two of the years. All improvements indicated are the most recent data relative to the baseline, which is the first time the assessments were done. The farms are pasture-based dairy farms in the Eastern Cape (Tsitsikamma, Oyster Bay, Humansdorp, Cookhouse, Cradock and Alexandria).

Discipline: lameness; Keywords: claw health, dirt lot, free stall, sole ulcer, white line.

Claw health is an important factor in animal welfare and its evaluation is an early indicator of lameness in dairy cattle. However, claw disorders on many farms are not routinely evaluated and the information not included in genetic evaluations as they are not always considered in terms of productivity. The aim of the study by the authors cited below was to evaluate claw health of dairy cattle housed in dirt lot vs free stall under the TMR systems.

Discipline: crossbreeding; Keywords: milk production, adaptability, Nguni, veld supplementation, suckling, temperament.

Discipline: genomic assessment; Keywords: homozygosity, pedigree-based inbreeding, dairy breeds, Dairy Genomics Program.

Small effective population sizes and inbreeding are major challenges faced by dairy cattle populations worldwide. Estimates of pedigree-based inbreeding (FPED) are unreliable due to a lack of pedigree data and pedigree errors and that may lead to an underestimation of inbreeding rates. Thus, inbreeding based on runs of homozygosity (FROH) has become the preferred method of estimating inbreeding as it is able to accurately predict the amount of autozygosity within the genome. No genomic estimates for inbreeding in SA dairy breeds are currently available, and therefore the aim of the study of the authors cited below was to estimate genomic inbreeding and effective population sizes for these breeds.

Discipline: selection; Keywords: female fertility, service records, pedigree data, genetic evaluations.

Female fertility is a fundamental trait for a profitable dairy herd enterprise. Studies have shown a decline in fertility probably because of dedicated selection for increased milk production. Age at first calving (AFC) and calving interval (CI) are prominent indicator traits to improve fertility, but these traits are greatly affected by management decisions. Service data present additional selection criteria with minimum bias. Service data are not recorded routinely into the national database but are kept on farm for management purposes, but should be useful to the selection effort. Therefore, the aim of the study by the authors cited below was to estimate genetic parameters for AI service-based heifer and cow fertility traits in Holstein herds.

Discipline: rumen fermentation; Keywords: feed additives, amino acids fluid-associated bacteria, particle-associated bacteria

Discipline: production; Keywords: smallholder, normative and deterministic model, herd profitability, gross margins.