Urine Calcium But Not Plasma Calcium or Urine Hydroxyproline Is Increased by a Systemic Acidosis in the Dairy Cow

Eight non-lactating, pregnant Holstein-Friesian cows were allocated to two treatments and individually offered diets differing in dietary cation-anion difference. Decreasing the dietary cation-anion difference reduced the urine pH within hours of anionic salt supplementation. Plasma calcium concentration was unaffected by dietary cation-anion difference but urine calcium concentration was significantly increased within 10 days of including anionic salts in the diet. Faecal calcium concentration was significantly reduced, indicating increased calcium absorption. Dietary calcium concentration or dietary cationanion difference did not significantly affect urinary hydroxyproline

Dry Matter Intake of Periparturient Cows on a Fresh Pasture/Pasture-Hay Diet

Reports of the depression in dry matter intake in the periparturient period have been inconsistent and little dry matter intake data is available for an all-forage diet prior to calving. Data to examine intake depression prior to calving was obtained from two experiments. In experiment 1, sixteen non-lactating, periparturient cows ate 1.3% of pre-calving body weight of grass-hay and freshly cut grass for two weeks pre-calving (restricted). Experiment 2 comprised thiry-six cows that ate 1.6% of pre-calving body weight of grass-hay and freshly cut grass for the final two weeks of pregnancy (ad libitum). Individual dry matter intakes were recorded for 14 days pre-calving. Intake pre-calving was not depressed, irrespective of feeding level, until two days pre-calving. This suggests that when an all-forage diet is fed pre-calving, increasing the energy density of the diet to compensate for a depression in dry matter intake may not be necessary

Evaluating the Benefits of Restricted Grazing to Protect Wet Pasture Soils in Two Dairy Regions of New Zealand

Many dairy farms in the Manawatu and Southland regions of New Zealand have poorly drained soils that are prone to treading damage, an undesirable outcome on grazed pastures during the wetter months of the year. Removing cows to a stand-off pad during wet conditions can reduce damage, but incurs costs. The objective of this study was to evaluate the impact of different levels of restricted grazing (from 0 to 10 hours grazing time/day for lactating cows) on pasture yield, damage and wastage, feed and stand-off expenses, and farm operating profit. A simulated farm from each region was used in a farm systems model. This model simulated pasture-cow-management interactions, using site-specific climate data as inputs for the soil-pasture sub-models. Days to recover previous yield potential for damaged paddocks can vary widely. A sensitivity analysis (40 to 200 days to recover) was conducted to evaluate the effect of this parameter on results. Full protection when there is risk of damage (0 grazing hours/day) appeared to be less profitable compared with some level of grazing, because the advantages of reduced damage were outweighed by the disadvantages of managing infrequently grazed pastures. The differences in operating profit between full protection and some level of grazing became less as the recovery time increased, but for both regions grazing durations of 6-8 hours/day when a risk of damage is present appeared to be a sensible strategy irrespective of recovery time