BRIEF COMMUNICATION: Heritability of IGF-1 and its genetic correlation with milk yield in Holstein-Friesian cows in selected Victorian herds

摘要

Insulin-like growth factor-1 (IGF-1) is a small peptide, produced mainly in the liver. It controls the growth and differentiation of many cell types through stimulation of the cell cycle (Rechler & Nissley, 1990). IGF-1 has been implicated as being involved in many biological processes and is thought to be related to milk production and reproductive potential of the dairy cow due to its association with the partitioning of nutrients among biological functions (Bauman & Currie, 1980) and its direct stimulatory affect on the ovaries (Spicer et al., 1993). Recent studies in Holstein-Friesian (HF) cows on pasture-based diets found that plasma IGF-1 concentrations in early lactation were affected by nutrient intake, and that inter-animal variation was greater than within-animal variation (Obese, 2003). This was confirmed in pasture based diets by a study conducted in New Zealand by Fahey et al. (2003). Studies by Moyes (2004) show there is an opportunity to rank cows within a herd on their plasma concentrations of IGF-1 after assaying a limited number of samples within a lactation, or possibly over a lifetime. The rankings have the potential to be related to parameters for milk yield and composition as well as reproductive performance and could therefore be used as a tool in dairy cow management and breeding programs.