Feeding, production, and efficiency of Holstein-Friesian, Jersey and mixed-breed lactating dairy cows in commercial Danish herds

Production efficiency is usually highly correlated with level of production. Therefore, it is assumed that by selecting and feeding for high milk production, one would also make significant strides in production efficiency. However, high milk production can also be achieved by high feed intake capacity, without necessarily resulting in improved production efficiency. One is concerned that the increased size of Holsteins is due to selection for feed intake capacity. The better procedure would have been to select for residual feed intake, which is the difference between the energy requirements for a particular milk production and the energy intake of the cow. Ideally, one would prefer the intake of the cow to be lower than the requirements, as that would mean improved production efficiency. It would also lower feed cost in the herd, and one would guess eventually lowering cow size, and therefore maintenance cost of the herd. This is in theory, and there is limited data to substantiate this hypothesis. We need test data in South Africa for this purpose. Dr Kristensen and colleagues in Denmark to some extent tested the hypothesis in a study between breeds, which is not ideal, because one should really do such a study within breeds. Nevertheless, the study provided some pointers. The study was published in the Journal of Dairy Science, Volume 98 of 2015, pages 263 to 274, under the title: Feeding, production, and efficiency of Holstein-Friesian, Jersey, and mixed-breed lactating dairy cows in commercial Danish herds.

The objective of their paper was to compare efficiency measures, milk production, and feed intake for lactating cows in commercial herds using different breeds and production and milking systems. To accomplish this, they used all feed evaluations made by the Danish extension service during the period November 2012 to April 2013 for 779 herds, of which 508 were Holstein-Friesian, 100 were Jersey and 171 herds were a mixture of these two breeds, other dairy breeds, and crossbreeds (termed “other”). The annually recorded, herd-average energy-corrected milk yield was 8,716 kg for Jerseys and 9,606 kg for Holsteins. The average herd size for Holsteins was 197 cows and 224 cows for Jerseys. All cows were fed a total mixed or partial mixed ration supplemented with concentrate from feeding stations, housed in loose housing systems with a slatted floor, and milked in either a parlour milking unit or an automatic milking system. Energy efficiency was calculated as net energy efficiency defined as total energy demand as a percentage of energy intake and as residual feed intake defined as energy intake minus energy requirement. Production efficiency was expressed as kilograms of energy corrected milk per kilogram of dry matter intake, kilograms of energy corrected milk per 10 megajoule of net energy intake, kilograms of energy corrected milk per 100 kg of bodyweight, and kilograms of dry matter intake per 100 kg of bodyweight. Environmental efficiency was expressed by nitrogen efficiency calculated as nitrogen in milk and meat as a percentage of nitrogen in intake, and as enteric emission of methane expressed as kilograms of energy corrected milk per megajoule of methane.

Mean milk yield for lactating cows was 30.4 kg of energy corrected milk in Holsteins, 3 kg less in Jerseys, with “other” herds in between, as were the case for most other parameters. The mean net energy intake available for lactation (meaning the maintenance requirement was subtracted) was 122 megajoules in Jerseys, increasing to 147 megajoules in Holsteins. More of the variation in energy corrected milk production was due to differences in dry matter intake in Holstein herds than in Jerseys, which suggests that selection for intake capacity was more pronounced in Holsteins than in Jerseys. Jerseys were more efficient than Holsteins and “others” for both production and environmental parameters, except for nitrogen efficiency, where no significant difference between breeds was recorded. Most of the efficiency measures were internally significantly correlated and in general highly positively correlated with milk production, whereas the correlation to dry matter intake was less positive and for Jerseys negative for net energy efficiency, kilograms of energy corrected milk per kilogram of dry matter intake, and nitrogen efficiency.

The difference in efficiency parameters between Holsteins and Jerseys was largely explained by the difference in residual feed intake, because less emphasis was put on intake capacity in Jerseys than in Holsteins. The results give some support to the argument above, but one would like to see results of research within breeds, rather than between breeds.