Effect of dietary energy source on energy balance, production, metabolic disorders and reproduction 
in lactating dairy cattle

Feeding a high concentrate (HC) diet is a widely used strategy for supporting high milk yields, yet it may cause certain metabolic disorders. This study aimed to investigate the changes in milk production and hepatic metabolism in goats fed different proportions of concentrate in the diet for 10 weeks. In total, 12 mid-lactating goats were randomly assigned to an HC diet (65% concentrate of dry matter, n = 6) or a low concentrate (LC) diet (35% concentrate of dry matter, n = 6). Compared with LC, HC goats produced greater amounts of volatile fatty acids and produced more milk and milk lactose, fat and protein ( P < 0.01). HC goats showed a greater concentration of ATP, NAD, plasma non-esterified fatty acids and hepatic triglycerides than LC goats ( P < 0.05). Real-time PCR results showed that messenger RNA (mRNA) expression of gluconeogenic genes, namely, glucose-6-phosphatase, pyruvate carboxylase and phosphoenolpyruvate carboxykinase were significantly up-regulated and accompanied greater gluconeogenic enzyme activities in the liver of HC goats. Moreover, the expression of hepatic lipogenic genes including sterol regulatory elementbinding protein 1c, fatty acid synthase and diacylglycerol acyltransferase mRNA was also up-regulated by the HC diet ( P < 0.05). HC goats had greater hepatic phosphorylation of AMP-activated protein kinase than LC ( P < 0.05). Furthermore, histone-3-lysine-27-acetylation contributed to this elevation of gluconeogenic gene expression. These results indicate that lactating goats fed an HC diet for 10 weeks produced more milk, which was associated with up-regulated gene expression and enzyme activities involved in hepatic gluconeogenesis and lipogenesis.Keywords: milk performance, gluconeogenesis, lipogenesis, high concentrate diet, lactating dairy goats ImplicationsFeeding a high concentrate diet to ruminants is a common strategy for maintaining high milk yields. Unfortunately, there is a strong correlation between the amount of concentrate feeding and the occurrence of acidosis and fatty liver in practice, which will decrease animal welfare and result in significant economic losses. As the vital metabolic organ, the liver is responsible for nutrient partitioning and contributes to the input of substrate precursors to the mammary gland for milk production. Therefore, it is important to investigate changes of hepatic metabolism in lactating ruminants fed a high concentrate diet, which will help elucidate the internal mechanism behind these metabolic changes.

Section: Discussionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

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Changes in milk performance and hepatic metabolism in mid-lactating dairy goats after being fed a high concentrate diet for 10 weeks

Dong

Sun

Cong

et al. 2017

“…Recently, several laboratories have examined the effects of glucogenic-lipogenic feeding strategies for dairy cows on reproductive function (Garnsworthy et al, 2009;Friggens et al, 2010). There is evidence that the administration of a glucogenic diet, which promotes increased circulating concentrations of insulin and glucose (Van Knegsel et al, 2005), would be expected to improve several reproductive variables. Gong et al (2002) found that the administration of a glucogenic diet increased circulating concentrations of insulin and increased the proportion of cows ovulating by 50 days after calving, which is highly desirable.…”

Section: Anovulatory Anoestrusmentioning

confidence: 99%

Parturition to resumption of ovarian cyclicity: comparative aspects of beef and dairy cows

Crowe

Diskin

Williams

2014

107

There is a variable anoestrous period following parturition in the cow. Follicular growth generally resumes within 7 to 10 days in the majority of cows associated with a transient FSH rise that occurs within 3 to 5 days of parturition. Dairy cows that are not nutritionally stressed generally ovulate their first postpartum dominant follicle (~15 days), whereas beef suckler cows in good body condition normally have a mean of 3.2 ± 0.2 dominant follicles (~30 days) to first ovulation; moreover, beef cows in poor body condition have a mean of 10.6 ± 1.2 dominant follicles (~70 to 100 days) to first ovulation. The lack of ovulation of dominant follicles during the postpartum period is associated with infrequent LH pulses, with both maternal-offspring bonding and low body condition score (BCS) at calving being implicated as the predominant causes of delayed resumption of cyclicity in nursed beef cows. In dairy cows, the normal pattern of early resumption of ovulation may be delayed in high-yielding Holstein type cows generally owing to the effects of severe negative energy balance, dystocia, retained placental membranes and uterine infections. First ovulation, in both dairy and beef cows, is generally silent (i.e., no behavioural oestrus) and followed by a short inter-ovulatory interval (>70%). The key to optimizing the resumption of ovulation in both beef and dairy cows is appropriate pre-calving nutrition and management so that cows calve down in optimal body condition (BCS; 2.75 to 3.0) with postpartum body condition loss restricted to < 0.5 BCS units.

“…For example, current mechanistic models to estimate methane emission in cattle are based on nutritional models developed to predict the type of nutrient available for absorption (Mills et al, 2001). In these mechanistic models, the stoichiometry of VFA formation is essential as the type of VFA absorbed is usually categorised into glucogenic or lipogenic, and the ratio between glucogenic or lipogenic nutrients affects milk production and composition as well as energy balance of dairy cattle (Van Knegsel et al, 2005). At the same time the production of methane is also related to the type of VFA formed.…”

Section: Environmental Pollutionmentioning

confidence: 99%

Predicting the profile of nutrients available for absorption: from nutrient requirement to animal response and environmental impact

Dijkstra

Kebreab

Mills

et al. 2007

Current feed evaluation systems for dairy cattle aim to match nutrient requirements with nutrient intake at pre-defined production levels. These systems were not developed to address, and are not suitable to predict, the responses to dietary changes in terms of production level and product composition, excretion of nutrients to the environment, and nutrition related disorders. The change from a requirement to a response system to meet the needs of various stakeholders requires prediction of the profile of absorbed nutrients and its subsequent utilisation for various purposes. This contribution examines the challenges to predicting the profile of nutrients available for absorption in dairy cattle and provides guidelines for further improved prediction with regard to animal production responses and environmental pollution.The profile of nutrients available for absorption comprises volatile fatty acids, long-chain fatty acids, amino acids and glucose. Thus the importance of processes in the reticulo-rumen is obvious. Much research into rumen fermentation is aimed at determination of substrate degradation rates. Quantitative knowledge on rates of passage of nutrients out of the rumen is rather limited compared with that on degradation rates, and thus should be an important theme in future research. Current systems largely ignore microbial metabolic variation, and extant mechanistic models of rumen fermentation give only limited attention to explicit representation of microbial metabolic activity. Recent molecular techniques indicate that knowledge on the presence and activity of various microbial species is far from complete. Such techniques may give a wealth of information, but to include such findings in systems predicting the nutrient profile requires close collaboration between molecular scientists and mathematical modellers on interpreting and evaluating quantitative data. Protozoal metabolism is of particular interest here given the paucity of quantitative data.Empirical models lack the biological basis necessary to evaluate mitigation strategies to reduce excretion of waste, including nitrogen, phosphorus and methane. Such models may have little predictive value when comparing various feeding strategies. Examples include the Intergovernmental Panel on Climate Change (IPCC) Tier II models to quantify methane emissions and current protein evaluation systems to evaluate low protein diets to reduce nitrogen losses to the environment. Nutrient based mechanistic models can address such issues. Since environmental issues generally attract more funding from governmental offices, further development of nutrient based models may well take place within an environmental framework.