Productive efficiency of dairy systems in temperate zones (with special reference to Latin America and Argentina)

Abstract

The way of expressing or estimating the stocking rate and the reproductive efficiency are simplifications that are made to carry out quantitative comparisons obtained from easily recordable data but that are undoubtedly debatable. Indeed, consider that the stocking rate (CA) could be better expressed if the live weight (PV) is used as an estimate of the potential food demand of the cow (instead of the number of cows) and the total amount of food offered in dry matter (instead of the number of hectares). Comparative stocking rate expressed as “kg PV/tonne total DM offered”. Regarding reproductive efficiency, there are other indicators that evaluate it better (for example, the pregnancy rate), but for a prolonged period of time (at least 5 years), the VO: VT ratio can be useful if, among others issues, the stock of animals is not increased and the length of lactation is normal. In dairy systems in temperate zones, energy is one of the main limiting nutrients in the systems. From the available information it can be inferred that in a pastoral system where the diet is based on “Gramineae”, an annual production ceiling of 15 liters/v/d (or 4,500 liters/lactation at 300 days) is to be expected as an annual average. In contrast, a diet based on alfalfa grazing could reach 25 liters/v/d (7,500 liters/lactation) on a sustained basis as evidenced by extensive information generated by INTA Rafaela (experimental trials and production models). This would also be the maximum achievable in pastoral systems. There is no doubt that the production system and its food approach depend on the price of milk, the price of inputs and the desired economic benefit.