Endocrine and metabolic status of commercial dairy goats during the transition period

Abstract

The aim of this study was to evaluate temporal variations in circulating levels of selected hormones and metabolites in commercial dairy goats during the transition period. Blood samples from 940 goats were collected weekly, from −3 to 3 wk relative to delivery, to measure the effects of level of milk production, parity number, and litter size on concentrations of glucose, β-hydroxybutyrate (BHB), fatty acids, and plasma urea nitrogen (PUN). A subset of 80 goats [40 low-yielding (LY, < 1.8 L/d) and 40 high-yielding goats (HY, > 3.7 L/d)] were selected from the study population to measure the effects of level of milk production on plasma concentration of insulin, prolactin, and growth hormone. Average (±SD) milk yield (from 3 to 30 d in milk), body weight, and body condition score for the study population were 2.4 ± 0.78 L/d, 70 ± 16.0 kg, and 2.5 ± 0.28 units, respectively. Milk yield was moderately correlated with parity number (r = 0.49) but had weak correlation with litter size (r = 0.14). In multiparous but not in primiparous goats, antepartum concentrations of fatty acids and BHB increased with increasing litter size. Concentrations of fatty acids, BHB, and PUN were consistently lower in primiparous goats compared with those in second or greater parity. Postpartum, HY goats had higher ratios of glucose, fatty acids, and BHB to insulin than did LY goats, which might explain the greater mobilization of body tissues and enhanced milk production observed in this group. Collectively, our results indicate that increased milk yield has the most significant influence on the magnitude of body tissue mobilization. Our results also show that goats of higher parity display higher levels of lipid mobilization, and that both pregnancy and lactation are less able to elicit lipomobilization in primiparous compared with multiparous goats.

Comparison of measures of insulin sensitivity in early-lactation dairy goats

“…For instance, we observed a positive correlation between RQUICKI and ECM (r = 0.56), which is similar to previous observations in dairy goats (r = 0.45, P < 0.001; Zamuner et al, 2020b). By applying the medical interpretation of RQUICKI values, one may be misled to believe that increasing milk production is associated with decreasing degree of IR, even though the most plausible explanation is that the observed positive relationship was due to decreased insulin and increased fatty acids concentration in animals of higher milk production, as demonstrated in Zamuner et al (2020a).…”

“…For instance, Marinković et al (2019) and Cincović et al (2014) reported a significant decrease in insulin concentrations (~35%) but an approximate 250% increase in fatty acids concentrations in postpartum cows. Conversely, in Zamuner et al (2020b), we observed that the increase in fatty acids concentration in postpartum goats (+188%) was accompanied by a more pronounced decrease in insulin concentration (−312%) compared with antepartum goats. Similarly, in Zamuner et al (2020a), we observed that greater fatty acids concentration in high-yielding goats (+20%) was accompanied by a much lower insulin concentration (−130%) compared with low-yielding goats.. Schoenberg and Overton (2011) pointed out the weaknesses of using RQUICKI to measure IR in ruminants, suggesting that interpretation of results between cows of different metabolic status or stage of lactation should be done with caution.…”

“…Indeed, several studies in dairy cows have suggested that RQUICKI is a better reflection of energy status than of IR itself (Schoenberg and Overton, 2011;Cincović et al, 2017;Hasegawa et al, 2019). Furthermore, comparisons between studies in goats and cows suggest that RQUICKI values are usually lower in postpartum cows compared with antepartum cows (Cincović et al, 2014;Marinković et al, 2019), whereas a retrospective analysis of data from our previous studies showed that RQUICKI values were lower in antepartum goats than in postpartum goats (0.43 vs. 0.49, P < 0.001, data not shown; Zamuner et al, 2020b) and lower in low-yielding goats than in high-yielding goats in early lactation (0.42 vs. 0.50; P = 0.01, data not shown; Zamuner et al, 2020a).…”

Factors affecting postpartum ovarian activity of goats in tropical semi-arid region

“…Endogenous opioids and the dopaminergic and serotoninergic systems are associated with nutrition mediate LH pulses (78). Some authors observed that an increase in plasma glucose availability increased GH and insulin secretion, acting directly on the follicular dynamics (68,75).…”

Surrogate Indexes of Insulin Resistance in Dairy Goats: Transitional Variation in Subclinical Hyperketonemia

“…Insulin resistance (IR) is a homeorhetic adaptation in ruminants for partitioning nutrients to support the uterus and mammary gland during the peripartum period [8]. Several surrogate indexes of IR (sIR) are developed to estimate INS sensitivity in human and veterinary medicine, which are calculated on the basis of blood NEAF, BHBA, GLU, and INS.…”