Abstract
This study evaluated the effects of replacing corn with wheat on the lactation performance, ruminal fermentation, plasma metabolites and hormonal profiles of multiparous Holstein cows. Thirty-four multiparous cows were divided into two equal groups, based on parity, body condition score, and bodyweight. The basal diet was supplemented with 186 g/kg corn or wheat, and was offered from day -28 (±7) relative to the date of expected calving. After calving, all cows received the same diet for four weeks (day +28). The wheat diets increased (P <0.05) the body condition score in the peri-parturient period and caused greater changes in dry matter intake and bodyweight post-partum, with no differences in energy balance compared with the corn diets. Further, the wheat increased (P <0.05) the concentration of propionate in the rumen, thus reducing the ratio of acetate to propionate, and produced (P <0.05) more milk and milk protein, but had reduced levels of urea nitrogen in the milk and serum. Similarly, the wheat diets increased (P <0.05) the plasma concentrations of albumin and glucose, and reduced (P <0.05) triglycerides with no effect (P >0.10) post partum on insulin, cortisol, β-hydroxybutyric acid and aspartate aminotransferase. The replacement of corn with wheat increased (P <0.05) plasma calcium and reduced non-esterified fatty acids around calving (day 0±1) and post-partum (days 0 to +28), and reduced urinary pH during the last week relative to the date of expected calving.Keywords: calving, energy balance, grain source, peri-parturient period
Highlights
Feeding dairy cows during the peri-parturient period for optimum post-partum performance is challenging, because rumen capacity and dry matter intake (DMI) are reduced owing to the space that is required for the gravid uterus during late gestation (Stanley et al, 1993)
Hypocalcaemia occurs from days 0 to 3 post-partum, and is a nutritional deficiency that is characterized by a reduction in serum calcium (Ca) concentration that does not return to normal for several days (Wankhade et al, 2017)
Corn was replaced with wheat in the diet for multiparous Holstein cows during the peri-parturient period, and the effects of this replacement were evaluated on DMI, lactation performance, ruminal fermentation, plasma metabolites, and hormonal profiles
Summary
Feeding dairy cows during the peri-parturient period for optimum post-partum performance is challenging, because rumen capacity and dry matter intake (DMI) are reduced owing to the space that is required for the gravid uterus during late gestation (Stanley et al, 1993). The difference between energy intake through diet and output through milk production puts the cows into negative energy balance from parturition to 35 days post-partum (Wankhade et al, 2017) This deficiency in the net energy balance predisposes lactating animals to oxidative stress (Sharma et al, 2011) and leads to metabolic and immunological disorders such as ketosis, fatty liver syndrome, and milk fever (hypocalcaemia). It was hypothesized that wheat grain in pre-partum diets would mimic the exogenous acidogenic sources in peri-parturient diets, resulting in reduced dependency on exogenous supplements, by increasing the rumen propionate production, reducing extra-cellular alkalinity, and maintaining Ca homeostasis, reducing the chances of hypocalcaemia and other metabolic disorders around calving. Corn was replaced with wheat in the diet for multiparous Holstein cows during the peri-parturient period, and the effects of this replacement were evaluated on DMI, lactation performance, ruminal fermentation, plasma metabolites, and hormonal profiles
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