Modeling mammary amino acid metabolism

Influence of levels of supplementary concentrate mixture on lactation performance of Red Sokoto does and the pre-weaning growth rate of their kids

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Concentrate mixture containing palm oil was fed at graded levels to lactating goats

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Total DMI increased with concentrate level and intake of hay was not compromised

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Higher concentrate levels improved daily milk yield by 48% with higher persistency of production

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Dam milk yield accounted for 61% variation in kids pre-weaning daily weight gain

Twenty pregnant Red Sokoto goats (liveweight, 28 ± 1.30 kg) were used in a completely randomized design to determine the effect of varying levels of concentrate on lactation performance. The concentrate, which contained 4% palm oil, was fed at levels of 1.0, 1.5, 2.0 and 2.5% of body weight of the does in addition to a basal diet of Digitaria smutsii hay offered ad libitum. The corresponding dietary treatments were designated as 1.0%C, 1.5%C, 2.0%C and 2.5%C, respectively. The goats were balanced for parity and randomly allocated to give five animals per treatment, and stall-fed individually.

The intake of dry matter and daily milk production linearly and quadratically increased (P<0.05) to the levels of concentrate supplementation. Increase in level of concentrate mixture supplementation affected (P<0.05) milk fat content and milk fat yield, but not other milk constituents. Persistency of milk production was numerically higher at higher levels of concentrate supplementation. Whereas 1.0%C, 1.5%C and 2.0%C could not prevent weight loss in the does, the 2.5%C significantly (P<0.05) promoted average daily gain (11.11 g/head/day) during lactation. The dam milk yield significantly (P<0.01) accounted for 61% of variation in kids pre-weaning average daily gain (ADG). It is concluded that concentrate mixture containing 4% palm oil can be fed at 2.5% of body weight without adverse effect on total dry matter intake, while enhancing postpartum weight gains, higher milk yield, persistency of milk production, pre-weaning growth of kids in Red Sokoto goats.

Optimising Milk Composition

During recent decades, the UK dairy industry has had to adjust to the introduction of milk quotas in 1984, the deregulation of milk markets in 1994, and accommodate changes in the demand for dairy products. The combination of these factors, in addition to Bovine Spongiform Encephalopathy and Foot and Mouth disease, and a fall in milk price has inevitably resulted in a restructuring of the industry, but also reinforced the need for all sectors of the industry to respond to the prevailing economic climate and changes in consumer preferences.

Nutrition in mammary gland health and lactation: Advances over eight Biology of Lactation in Farm Animals meetings1

Over the years, numerous studies have investigated the mechanisms controlling nutrient availability and metabolism in the mammary gland and how dietary interventions can influence these processes. The development of in vivo and in vitro systems made it possible to explore the trafficking and metabolic fate of nutrients and how these are influenced by hormones. To improve the quality and safety of milk products, attention has focused on improving animal health in general and mammary gland health in particular and also on enhancing the milk content of natural bioactive milk components that promote the health of human neonates and adults. In the past, attempts to probe the relationship among nutrition, animal health, and animal products were limited to administering single dietary components and investigating their biochemical and metabolic effects. Today, we have genomics, proteomics, and related technologies that allow us to pursue more holistic investigational strategies. These new technologies are providing new insights into interactions among nutrition, lactation, and product quality. The aim of this paper is to review advances in nutritional support of mammary gland function and health as presented in 14 yr of Biology of Lactation in Farm Animals (BOLFA) meetings.

An integrative model of amino acid metabolism in the liver of the lactating dairy cow

The objective of this work was to construct a dynamic model of hepatic amino acid metabolism in the lactating dairy cow that could be parameterized using net flow data from in vivo experiments. The model considers 22 amino acids, ammonia, urea, and 13 energetic metabolites, and was parameterized using a steady-state balance model and two in vivo, net flow experiments conducted with mid-lactation dairy cows. Extracellular flows were derived directly from the observed data. An optimization routine was used to derive nine intracellular flows. The resulting dynamic model was found to be stable across a range of inputs suggesting that it can be perturbed and applied to other physiological states. Although nitrogen was generally in balance, leucine was in slight deficit compared to predicted needs for export protein synthesis, suggesting that an alternative source of leucine (e.g. peptides) was utilized. Simulations of varying glucagon concentrations indicated that an additional 5 mol/d of glucose could be synthesized at the reference substrate concentrations and blood flows. The increased glucose production was supported by increased removal from blood of lactate, glutamate, aspartate, alanine, asparagine, and glutamine. As glucose output increased, ketone body and acetate release increased while CO(2) release declined. The pattern of amino acids appearing in hepatic vein blood was affected by changes in amino acid concentration in portal vein blood, portal blood flow rate and glucagon concentration, with methionine and phenylalanine being the most affected of essential amino acids. Experimental evidence is insufficient to determine whether essential amino acids are affected by varying gluconeogenic demands.