Effect of feed restriction on dairy cow milk production: a review

Abstract

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.

Effect of different dietary regimens at dry-off on performance, metabolism, and immune system in dairy cows

“…In line with the lower metabolic priority of the mammary gland at this stage of lactation, the adjustment of milk production contributed to the maintenance of glucose homeostasis. Therefore, the availability of glucose was not limiting for milk fat production, which was further supported by increased plasma NEFA due to enhanced lipolysis (Pullen et al, 1989;Gross et al, 2021a;Leduc et al, 2021). Milk protein and lactose contents did not show any major changes throughout our experiment, even though some studies showed partial alterations after an induced feed restriction depending on its severity, duration, and the lactational stage (Kvidera et al, 2017;Leduc et al, 2021).…”

“…Feed restriction is one approach to reduce milk production and therefore to facilitate the dry-off process (Ollier et al, 2014). A recent meta study investigating studies with different intensity levels of feed restrictions carried out during different stages of lactation revealed that milk yield significantly decreased in 41 out of 44 studies (Leduc et al, 2021). Despite the immediate decline in milk production and the short duration of feed restriction until the cessation of milking in the present study (approximately 30% after 3 d of feed restriction), the calculated EB remained negative until dry-off, where it turned positive again.…”

“…Therefore, the availability of glucose was not limiting for milk fat production, which was further supported by increased plasma NEFA due to enhanced lipolysis (Pullen et al, 1989;Gross et al, 2021a;Leduc et al, 2021). Milk protein and lactose contents did not show any major changes throughout our experiment, even though some studies showed partial alterations after an induced feed restriction depending on its severity, duration, and the lactational stage (Kvidera et al, 2017;Leduc et al, 2021). In terms of the relatively low milk yield and high concentrate amounts fed before the start of feed restriction, we assume that the intensity of the realized feed restriction and its short duration in our experiment might have been not severe enough to provoke changes in all milk components.…”

Milk proteins as a feed restriction signature indicating the metabolic adaptation of dairy cows

“…A rise in the fat content of up to 13% was due to the uptake of long chain fatty acids from lipid mobilization, as indicated by the increase in plasma NEFA concentrations seen during both trials. Such adaptations of lipid metabolism in the context of a negative energy balance have already been well described 1,18,19 , and notably involved the downregulation of several mammary lipogenic genes during the first days of short-term feed restriction 17 . However, during our M trial, concentrations of fatty acid synthase rose slightly after five days of feed restriction, suggesting that intense restriction is necessary for this shift in fatty acid metabolism to occur.…”

Full-lactation performance of multiparous dairy cows with differing residual feed intake

“…The average level of insulin in plasma was lower while NEFA was higher in LRFI NorFor cows during the first six weeks of lactation. Insulin and NEFA reflects EB as reviewed by Leduc et al [33]. A limitation with the present study is that blood was collected only at three occasions; a more frequent sampling might have given a more detailed picture of the metabolism.…”