Responses of North American and New Zealand strains of Holstein–Friesian dairy cattle to homeostatic challenges during early and mid-lactation

Abstract

This study investigated the physiological basis of differences in nutrient partitioning between the North American (NA) and New Zealand (NZ) strains of Holstein-Friesian cattle by determining the responses to homeostatic challenges at two stages of lactation. Glucose tolerance tests, epinephrine challenges and insulin challenges were carried out on consecutive days commencing on day 32 6 0.48 (mean 6 s.e.) of lactation (T1) and again commencing on day 137 6 2.44 of lactation (T2). The insulin and non-esterified fatty acid (NEFA) responses to glucose infusion did not differ between the strains. The NZ strain had a greater clearance rate (CR) of glucose (2.04% v. 1.66%/min) and tended to have a shorter (34.4 v. 41.1 min) glucose half-life (t 1 2 ) at T2 when infused with glucose. The NA cows had a greater glucose response to epinephrine infusion across T1 and T2, and tended to have a greater insulin response to epinephrine infusion. Plasma NEFA concentration declined to similar nadir concentrations for both strains at T1 in response to insulin, though from a higher basal concentration in NA cows, resulting in a greater (22.29 v. 21.38) NEFA area under the response curve for NA cows. Glucose response to insulin varied with time, tending to be greater for NA at T1, but tending to be lower for NA at T2. The results indicated that NA cows had a greater glycogenolytic response to epinephrine, but both strains had similar lipolytic responses. The results also imply that higher basal circulating NEFA concentrations in the NA strain in early lactation were not due to diminished adipose tissue responsiveness to insulin. There were indications that glucose CR was greater in NZ cows in mid-lactation, and may form the basis of increased body tissue accretion during mid-to late-lactation in this strain.

Effects of dietary energy allowance and decline in dry matter intake during the dry period on responses to glucose and insulin in transition dairy cows

“…The decrease in responsiveness to insulin seems to have commenced before calving because the cows with a shorter interval to actual calving day at the time of the prepartal IC tended to have a lower NEFA CR. The observed tendency for a difference in CR of NEFA between CEI and HEI cows in IC may not indicate altered responsiveness of adipose tissue to antilipolytic actions of insulin given that NEFA was reduced to a similar nadir (Patton et al, 2009). The strong rebound of plasma NEFA concentration 60 min after glucose infusion in postpartal IVGTT indicates resumption of lipolysis, potentially because of the increasing plasma adrenaline concentration (Sumner et al, 2004) and increased sensitivity of adipose tissue to lipolytic stimulation (Drackley et al, 2005;Kokkonen et al, 2005;Roche et al, 2013).…”

“…In agreement with our results in prepartal cows, Schoenberg et al (2012) observed that dry cows fed a high-energy diet had lower NEFA suppression in the fed state than cows fed a low-energy diet. Patton et al (2009) studied strain differences in homeostatic challenges in early lactation and found that North American strains of Holstein-Friesian cattle with higher basal NEFA had a greater suppression of NEFA after IC in early lactation (32 d postpartum) compared with New Zealand-type Holstein-Friesian cattle despite an identical loss of BCS and a similar glucose response. According to the authors, the NEFA decrement was attributable to the higher basal NEFA, as both strains decreased to a similar nadir of NEFA.…”

“…Correspondingly, the negative correlation between the basal NEFA and the NEFA AUC suggests that the basal NEFA concentration affects the magnitude of the depression of NEFA after the glucose load. Finally, individual differences in the regulation of lipolysis may have contributed to the transitory effect of the dry period EI on the plasma NEFA responses (Patton et al, 2009;Weber et al, 2013). For instance, accretion of lipids between different adipose tissue sites varies in dairy cows (Drackley et al, 2014), and altered responses and sensitivity to catecholamines may mediate adipose tissue mobilization (Chilliard et al, 2000;Drackley et al, 2005;Roche et al, 2013).…”

Letter to the Editor: A response to Selvaraj and Boisclair (2019)

“…As we pointed out, however, there was a 6-to 8-h delay from termination of the infusion to recovery of the reproductive tract after slaughter and collection of the sample of uterine fluid. Intravenous administration of a large glucose bolus during a glucose tolerance test results in hyperglycemia and hyperinsulinemia, but both glucose and insulin concentrations in blood return to pretreatment baseline concentrations within approximately 1 h (Patton et al, 2009). Given the rapid kinetics of glucose metabolism, it is likely that any treatment effect on uterine luminal fluid glucose concentrations in the study of Leane et al (2018) would have disappeared by the time the samples were collected.…”

“…Regarding the plasma fatty acid concentrations, all cows were in late lactation and were not mobilizing lipid stores when the study took place (plasma fatty acid concentrations <0.2 mmol/L). After bolus administration of either glucose or insulin to cows in positive energy balance, plasma fatty acid concentrations exhibit little or no reduction (e.g., see Sechen et al, 1990;Patton et al, 2009). Hence, it was unlikely that plasma fatty acid concentrations would decline during the infusion, regardless of the absence of a treatment effect on circulating insulin concentrations.…”