Abstract
Thirty healthy Holstein dairy cows in the dry period were randomly divided into three groups and fed diets with different net energy for lactation (group A: 1.2 Mcal/kg DM, group B: 1.3 Mcal/kg DM, and group C: 1.4 Mcal/kg DM) for 8 weeks prepartum. Thereafter, dairy cows were fed a diet of the same formulation (1.66 Mcal/kg DM) for 12 weeks postpartum. The effects of different dietary energy densities in the dry period on postpartum performance and metabolic parameters of dairy cows were observed. Milk yield was reduced by 14.5% in the low-energy diet group; however, there were no differences in milk composition between the three groups. Postpartum plasma β-hydroxybutyrate, non-esterified fatty acid, growth hormone, and glucagon levels were significantly decreased whereas leptin and neuropeptide levels were elevated in the low-energy diet group. Moreover, body fat mobilization was attenuated, and the decline in postpartum body condition was reduced in the low-energy diet group, thus effectively reducing the postpartum negative energy balance.
Highlights
The greatest metabolic characteristic of dairy cows in early lactation is negative energy balance (NEB) due to insufficient energy intake that fails to meet the needs
Thirty healthy Holstein dairy cows were selected with consistent age, parity (2.5 ± 0.57), and body condition (3.17 ± 0.14), 305 days milk yield is more than 7000 kg (27.46 ± 1.72 kg everyday) The animals were randomly divided into three groups and fed diets of different net energies for lactation (NEL; group A: 1.2 Mcal/kg DM, group B: 1.3 Mcal/kg DM, and group C: 1.4 Mcal/kg DM) for 8 weeks prepartum
Medium-energy and high-energy feeding in the dry period increased the postpartum milk yield of dairy cows
Summary
The greatest metabolic characteristic of dairy cows in early lactation is negative energy balance (NEB) due to insufficient energy intake that fails to meet the needs. Increasing prepartum dietary energy density (DED) is commonly used to reduce the NEB; this approach often increases the incidence of postpartum metabolic diseases [1]. Evidence indicates that low-energy feeding for 60 - 30 days prepartum can increase postpartum DMI, reduced the NEB, attenuate body fat mobilization, and markedly decrease blood NEFA and BHBA levels of dairy cows [6] [7]. Beever reported that one-stage feeding (using diets with the same energy density throughout the dry period) improved the health and reproductive performance of cows on dozens of dairy farms in France, Britain, and Ireland [8]. We fed dairy cows diets of different energy densities in the dry period and observed their effects on postpartum production and metabolism to establish a new feeding pattern and appropriate energy density. This study lays the foundation and provides a theoretical basis to correct and reduce the postpartum NEB, improve the postpartum performance, and reveal the mechanism of metabolic diseases in dairy cows
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