Effects of prepartum grouping strategy on health, production, and reproduction of dairy cows

Abstract

The objectives of the current experiment were to determine the effect of two prepartum grouping strategies on health, metabolic, reproductive, and productive parameters of dairy cows. Jersey cows enrolled in the experiment at 253 ± 3 d of gestation (study d 0 = calving) were balanced for parity and projected 305-d mature equivalent and assigned to one of two treatments. Cows assigned to the traditional (TRD, n = 6) treatment were moved to the study pen as a group of 44 cows and weekly thereafter groups of 2 to 15 cows were moved to the study pen to re-establish stocking density. Cows assigned to the All-In-All-Out (AIAO, n = 6) treatment were moved to the study pen in groups of 44 cows, but no new cows entered the AIAO pen until the end of the replicate. A total of 308 and 259 cows were enrolled in the AIAO and TRD treatments, respectively. At the end of each replicate a new TRD and AIAO group started but pens were switched. Cows were milked thrice daily. Plasma non-esterified fatty acid (NEFA) concentration was measured weekly from study d -18 ± 3 to 24 ± 3 and plasma beta-hydroxy butyrate (BHBA) was measured weekly from study d 3 ± 3 to 24 ± 3. Cows were examined on study d 1, 4 ± 1, 7 ± 1, 10 ± 1 and 13 ± 1 for diagnosis of uterine diseases and had their ovaries scanned by ultrasound on study d 39 ± 3 and 53 ± 3 to determine resumption of ovarian cycles. Binomial data were analyzed by logistic regression using the GLIMMIX procedure and continuous data were analyzed by ANOVA using the MIXED procedure. Average stocking density was reduced for the AIAO (71.9%) treatment compared with the TRD (86.9%) treatment. Treatment did not affect the incidence of uterine diseases (TRD = 19.6, AIAO = 21.9%). Concentrations of NEFA (TRD = 80.4 ± 8.2, AIAO = 62.9 ± 8.5 µmol/L) and BHBA (TRD = 454.4 ± 10.9, AIAO = 446.1 ± 11.1 µmol/L) were not different between treatments. Percentages of cows that resumed ovarian cycles by study d 39 ± 3 (TRD = 70.8, AIAO = 63.1%) and 53 ± 3 (TRD = 90.1, AIAO = 90.2%) were not different between treatments. Similarly, treatment had no effect on rate of removal from the herd {TRD = referent, AIAO [(adjusted hazard ratio (95% confidence interval)] = 0.85 (0.63, 1.45)} or rate of pregnancy establishment [TRD = referent, AIAO = 1.07 (0.88, 1.30)]. Finally, treatment did not affect energy corrected milk yield (TRD = 34.4 ± 0.6, AIAO = 34.3 ± 0.7 kg/d). Considering that no benefits were observed regarding health, metabolic, reproductive and productive parameters the reduced stocking density and consequent increased cost of building prepartum facilities to accommodate an AIAO grouping strategy may not be justified.