Increased incidence of reproductive disorders associated with short gestation length in Holstein dairy cows.

The purpose of the current study was to investigate the effect of gestation length (GL) on productive performance, and the incidence of calving and reproductive diseases in Holstein dairy cows. In total, 3800 Holstein singleton cows (2000 heifers and 1800 cows) from two commercial dairy farms were used. The average gestation length for 3800 cows was 276 ± 6 d. Cows with GL shorter or longer than 3 SD from the mean were removed and considered outliers. This process led to the elimination of 20 cows from the 3800 cows enrolled in the study. Therefore, 3780 cows (1994 heifers and 1786 cows) remained for data analysis, with a range of GL between 258 and 294 d. The mean of GL for the remaining 3780 cows in the study was 276 ± 5 d, which were classified as short (SGL; more than 1SD less than the population mean, mean = 267, range 258-270 d), average (AGL; population mean ± 1SD, mean = 276, range 271-281 d), and long (LGL; more than 1SD greater than the population mean, mean = 284, range 282-294 d) gestation length. In primiparous cows, the incidence of stillbirth, retained placenta, metritis, and clinical endometritis were higher in the SGL cows than in the AGL cows, but the incidence of dystocia was similar across groups. In multiparous cows, the incidence of dystocia, retained placenta, and metritis were higher in the SGL cows than in the AGL cows, and the incidence of stillbirth was higher in the SGL and LGL cows than in the AGL cows. In primiparous cows, milk yield was not different across groups. However, in multiparous cows, the SGL cows had lower milk yield than the AGL cows. In primiparous cows, the SGL cows had lower colostrum production than the AGL cows, but in multiparous cows, there was no difference in colostrum production across groups. In general, cows with either short or long gestation length had impaired health and production, but this impact was more pronounced in cows with short gestation length.

Interactions of protein levels fed to Holstein cows pre- and postpartum on productive and metabolic responses.

The objective of this study was to examine the interaction between levels of dietary crude protein (CP) pre- and postpartum on feed intake, performance, and metabolic status of dairy cows with a 14-d close-up experimental period. Forty multiparous Holstein cows were blocked by expected calving date and previous lactation milk yield at -14 d relative to expected calving and randomly allocated to receive either a 12.5% CP diet with 3.3% rumen undegraded protein (RUP; 12pre) or a 15.2% CP diet with 5% RUP (15pre) based on dry matter (DM). From d 1 to 21 postpartum, cows within each prepartum group were randomly assigned to receive either a 16.1% CP diet with 4.9% RUP (16post) or a 18.6% CP diet with 6.8% RUP (19post) based on DM. The experiment was conducted as a split-plot design, with CP prepartum being the whole-plot factor and CP postpartum as the subplot factor. Diets were similar in net energy for lactation, and CP levels were increased by replacing grain with a combination of corn gluten meal and fish meal. In prepartum, cows fed the 15pre diet tended to consume more DM than cows fed the 12pre diet (9.65 vs. 9.30 kg/d). Except for blood urea nitrogen (BUN) concentration, no other blood metabolite in prepartum was affected by diets. The interaction between pre- and postpartum CP levels showed that elevating dietary CP from 16post to 19post increased DM intake (15.20 vs. 17.67 kg/d) and milk yield (35.16 vs. 40.26 kg/d) in 12pre cows but not in 15pre cows. Milk fat, protein, and lactose contents were not affected by the interaction between pre- and postpartum CP levels. Feeding 19post compared with 16post increased milk protein (1.28 vs. 1.08 kg/d) and lactose (1.86 vs. 1.61 kg/d) yields in 12pre cows, whereas this effect was not observed in 15pre cows. Milk urea nitrogen was elevated when dietary CP increased from 16post to 19post in 15pre cows (12.98 vs. 14.84 mg/dL) but not in 12pre cows. The concentrations of BUN were greater in 19post cows than in 16post cows for both 12pre (16.31 vs. 13.81 mg/dL) and 15pre (18.44 vs. 14.71 mg/dL) cows. The 19post cows had lower serum fatty acids than 16post cows (0.65 vs. 0.96 mmol/L) in 12pre but not in 15pre. However, a reduction in serum aspartate aminotransferase (AST) concentration was observed in 19post cows compared with 16post cows (68.30 vs. 98.24 U/L) when cows were fed 12pre. For cows fed 15pre, those fed 19post had higher serum AST levels than those fed 16post (86.61 vs. 67.74 U/L) during 21 d of lactation. Body weight and body condition score changes were not affected by interactive effects between pre- and postpartum CP levels, but 19post cows tended (-0.30 vs. -0.45) to have smaller body condition score losses than 16post cows when fed the 12pre diet. Overall, increasing dietary CP postpartum from 16 to 19% DM improved performance and metabolic status of cows fed 12% CP prepartum. The lack of responses to increased dietary CP postpartum in cows fed 15% CP prepartum suggests that dietary CP postpartum could decrease to 16% DM when cows are fed higher dietary CP prepartum.