Metabolic and production profiles of dairy cows in response to decreased nutrient density to increase physiological imbalance at different stages of lactation

Abstract

Physiological imbalance (PI) is a situation in which physiological parameters deviate from the normal, and cows consequently have an increased risk of developing production diseases and reduced production or reproduction. Our objectives were to (1) determine the effect of stage of lactation and milk yield on metabolic and production responses of cows during a nutrient restriction period to experimentally increase PI; (2) identify major metabolites that relate to degree of PI; and (3) identify potential biomarkers in milk for on-farm detection of PI throughout lactation. Forty-seven Holstein cows in early [n=14; 49±22 d in milk (DIM); parity=1.6±0.5], mid (n=15; 159±39 DIM; parity=1.5±0.5), and late (n=18; 273±3 DIM; parity=1.3±0.5) lactation were used. Prior to restriction, all cows were fed the same total mixed ration ad libitum. All cows were then nutrient restricted for 4 d by supplementing the ration with 60% wheat straw to induce PI. After restriction, cows returned to full feed. Daily milk yield was recorded and composite milk samples were analyzed for fat, protein, lactose, citrate, somatic cells, uric acid, alkaline phosphatase, β-hydroxybutyrate (BHBA), and milk urea nitrogen. Blood was collected daily and analyzed for metabolites: nonesterified fatty acids (NEFA), BHBA, glucose, plasma urea nitrogen, and insulin. The revised quantitative insulin sensitivity check index (RQUICKI) was calculated for each cow. Liver biopsies collected before and during restriction were analyzed for triglycerides, glycogen, phospholipids, glucose, and total lipid content. A generalized linear mixed model was used to determine the effect of stage of lactation on responses during restriction. Regression analyses were used to examine the effect of pre-restriction levels on changes during restriction. Similar decreases in milk yield among groups indicate that the capacity of individual responses is dependent on milk yield but the coping strategies used are dependent on stage of lactation. Milk yield was a better predictor of feed intake than DIM. Plasma glucose decreased for all cows, and cows in early lactation had increased plasma BHBA, whereas cows in later lactation had increased NEFA during restriction. Milk citrate had the greatest increase (58%) during restriction for all cows. Results reported here identified metabolites (i.e., glucose, NEFA, BHBA, cholesterol) as predictors of PI and identified milk citrate as a promising biomarker for PI on farm.

Composition of major proteins in cow milk differing in mean protein concentration during the first 155 days of lactation and the influence of season as well as short-term restricted feeding in early and mid-lactation

“…As intended, feed restriction during early and mid-lactation led to a reduced energy intake, but resulted in no significant change in energy balance in both LP-and HP-cows. Milk yield was slightly lower compared to previous results after a 50% restriction of DMI over 5 days in mid-lactation (-11 kg;Carlson et al, 2006) and a 40% nutrient restriction during 4 days (-10 kg; Bjerre-Harpøth et al, 2012). In LP-cows, the decrease in milk yield was significant due to higher milk yields before the restricted feeding in early and mid-lactation.…”

Effects of live weight adjusted feeding strategy on plasma indicators of energy balance in Holstein cows managed for extended lactation

“…In a previous study, some cows were restricted for 4 days, and the metabolic changes occurred during these restriction days. Then the cows were shifted back to the standard TMR diet ad libitum, and 1 week after, there were no metabolic differences between the groups (Bjerre-Harpoth et al, 2012). This result is similar to our result, where metabolic changes were detected during the shift period, but not 1 week after the last cow had been shifted to the control diet (from 10 to 12 WIM).…”

Are free glucose and glucose-6-phosphate in milk indicators of specific physiological states in the cow?

“…reflect the rate and extent of tissue mobilization and have been used to predict the energetic status of the animal (Bjerre-Harpøth et al, 2012) or used to generate indices like physiological imbalance (PI; Moyes et al, 2013). However, blood sampling is time-consuming and normally expensive to perform and are not optimal for use on-farm.…”