Influence of Energy Balance on Reproductive Performance and Milk Production of Dairy Cows at Pre-partum and Early Lactation Periods

Two experiments were conducted to evaluate the effects of chromium (Cr) supplementation on early lactation performance of Holstein cows. Experiment 1 involved 12 primiparous (PP) and 22 multiparous (MP) cows, while exp. 2 involved 18 PP and 22 MP cows. In each trial, cows were fed total mixed rations (TMR) and assigned to one of two treatments: control or 0.5 mg kg−1 supplemental chelated Cr from week 6 prepartum to week 16 postpartum The cortisol response to synthetic adrenocorticotropin (ACTH) intramuscular (i.m.) and the luteinizing hormone (LH) response to synthetic gonadotropin-releasing hormone (GnRH) i.m. were evaluated as well, during weeks 2 and 6 postpartum in exp. 2 During the first 16 wk of lactation, supplemental Cr tended to increase milk yields in PP cows by 13% (P = 0.06) and increased milk production by 7% (P < 0.05) in exps. 1 and 2, respectively, but had no effect in MP cows. Despite increased milk yield, Cr supplementation had no adverse effect on milk composition, reproductive performance, or health status. Furthermore, Cr supplementation tended to increase the milk lactose content in PP cows. Supplemental Cr reduced serum β-hydroxybutyrate levels and may reduce subclinical ketosis in MP cows. In addition, in overconditioned, aged cows, Cr supplementation may reduce the incidence of certain other metabolic disorders. Peak values and production rates of cortisol in Cr-supplemented cows tended to be greater (P < 0.10) than in control cows at week 6 Basal LH concentrations did not differ between the two treatments for either week However, the Cr-supplemented cows released less (P < 0.05) LH than did control cows at week 6. Results from hormonestimulation tests suggest that the Cr-supplemented cows may have experienced a greater stress with their increased milk production. However the time in postpartum anestrus and the time to conception were similar, suggesting that Cr supplementation may have mitigated the slower return to fertility usually seen in higher producing PP dairy cows. Further study is needed to determine the effects of Cr supplementation on reproductive performance, health status, and metabolic disorders in dairy cows. Key words: Chromium, milk production, luteinizing hormone, cortisol, reproduction, dairy cows

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The effect of energy balance and condition score on early lactation fertility in two genetic lines of Holstein cattle maintained in two contrasting feeding systems

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200019591 ◽

2007 ◽

Vol 2007 ◽

pp. 56-56

Author(s):

G. E. Pollott ◽

M. P. Coffey

Keyword(s):

Energy Balance ◽

Dairy Cows ◽

Reproductive Performance ◽

Dairy Cow ◽

Production Systems ◽

Body Condition Score ◽

Early Lactation ◽

Explanatory Factors ◽

Condition Score ◽

Feeding Systems

The ability of high-yielding modern dairy cows to perform in the range of systems found on UK dairy farms, and to be profitable and sustainable, needs investigating. As part of a project to study the robustness of such animals, milk-progesterone profiling was used to investigate the reproductive performance of two genotypes of dairy cow on two production systems (Pollott and Coffey, 2006). In this paper differences in fertility between genotypes and systems was investigated using energy balance (EB) and body condition score (CS) as explanatory factors.

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Transition Period of the Dairy Cow Revisited: II. Homeorhetic Stimulus and Ketosis With Implication for Fertility

Journal of Agricultural Science ◽

10.5539/jas.v12n3p25 ◽

2020 ◽

Vol 12 (3) ◽

pp. 25

Author(s):

Holger Martens

Keyword(s):

Energy Balance ◽

Dairy Cows ◽

Milk Production ◽

Milk Yield ◽

Transition Period ◽

Genetic Correlations ◽

Future Research ◽

Early Lactation ◽

Input And Output ◽

Fat Liver

Dairy cows have been selected during the last century primarily for milk production, which has been increased by a factor 3-5 per lactation during this period without a concomitantly adequate increase of dry matter intake (DMI). This discrepancy between input and output is caused by a negative or minutely positive genetic correlation between milk yield and DMI and leads, in high-producing dairy cows in early lactation, to a severe and long-lasting negative energy balance (NEB) with distinct hormonal and metabolic alterations. Milk production during this period is regulated by homeorhesis with high priority for this trait, which is relatively uncoupled from DMI, and hence with possible restrictions of other functions. The extent and duration of the current NEB is a health risk and is probably one of the reasons for genetic correlations between milk yield and disease. The gap between input and output is closed by the mobilization of reserves characterized by a rapid increase of non-esterified fatty acids (NEFA) above the acute requirement, in turn leading to ectopic fat disposition in the liver and other organs. Therefore, fat liver and ketosis occur during early lactation within a phase of the priority of the homeorhetic (genetic) regulation of milk production at insufficient DMI. Ketosis is correlated with an impairment of fertility. The correlation between an early cause (ketosis) and a later effect (impaired fertility) cannot be explained satisfactorily, but possible epigenetic alterations look promising for future research. The revealed connection between homeorhesis, fat liver and ketosis, and the impairment of fertility provides an approach for discussions of these topics as a complex. The convergence between these issues should furthermore be extended to other production diseases. Since the genetic background of this interaction must not be neglected, the current breeding system should include further health traits with a predominant emphasis on parameters of metabolism and energy balance.

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