Farm Table says:
Strategies for gain during late lactation and the far-off non-lactating period and their interaction with close-up dry matter intake
What is the problem?
In pasture-based dairy systems, cows generally are thinner at the end of lactation in comparison to cows fed total mixed rations with over-feeding of metabolizable energy (ME) during the far-off nonlactating period a standard management practice. This is to increase the body condition score (BCS). This study investigated an alternative management strategy, through having cows to gain BCS through late lactation, so that cows ended lactation close to optimum calving BCS and maintained BCS through to calving.
What did the research involve?
A herd of 150 cows was assigned to 1 of 2 feeding levels in late lactation to achieve a low and high BCS at the time of dry off (approximately 4.25 and 5.0 on a 10-point scale). After dry-off, herds were managed to achieve a BCS of 5.0 one month before calving. Cows were offered 65, 90, or 120% of their pre-calving ME requirements for 3 weeks pre-calving. Body weight and BCS were measured weekly before and after calving, and milk production was measured weekly until week 7 post-calving. Blood samples were collected weekly for 4 weeks pre-calving and 5 weeks post-calving, and on day 0, 1, 2, 3, and 4 relative to calving, and analyzed for blood fatty acids, β-hydroxybutyrate, calcium status, and inflammatory state.
What were the key findings?
No interaction was seen between far-off and close-up feeding levels. Over-feeding of ME to low BCS cows during the far-off nonlactating period reduced blood fatty acid and β-hydroxybutyrate concentrations and increased blood albumin to globulin ratio. Cows consuming 65% of their ME requirements during the close-up period had lower fatty acids and β-hydroxybutyrate in early lactation, but produced less milk, particularly during the first 21 days of lactation, had a 3-fold greater concentration of haptoglobin immediately post-calving, and had a lower blood cholesterol concentration and albumin to globulin ratio, when compared with cows offered 90 or 120% of their ME requirements. These measurements show a restriction in the close-up nonlactating period increases the risk of disease in early lactation and reduces milk production.
Far-off overfeeding of ME to cows needing to gain BCS did not influence peripartum metabolic health in grazing dairy cows, but restricting cows below 70% ME requirements during the close-up transition period resulted in a blood profile showing inflammation.