Effect of energy balance profiles on metabolic and reproductive response in Holstein and Swedish Red cows

Highlights

• Relationships between fertility parameters, residual feed intake, and BCS profiles.

• Phenotypic data related to fertility variables from cows with different genetic background on different feeding strategies.

• Sustainable management approaches that valorize the adaptive responses of dairy cows to low and high input dairy systems.

Abstract

This study examined the effect of two feeding levels during the antepartum and postpartum period on reproductive performance and blood metabolites (glucose, non-esterified fatty acids (NEFA), insulin) in primiparous Holstein and Swedish Red (SRB) cows, in order to identify possible differences in the way these breeds respond to negative energy balance after calving. A total of 44 cows (22 Holstein, 22 SRB) kept in a loose housing system were included in the study. The control group (HE, n = 23) was fed a diet for high-producing cows (target 35 kg/d energycorrected milk, ECM). A lower feeding intensity (LE, n = 21) was achieved by giving -50% concentrate to target 25 kg/d ECM. Diets were implemented 30 days before expected calving and the cows were monitored for 120 days postpartum. Milk yield and composition, dry matter intake (DMI), live body weight and body condition score (BCS) were assessed to calculate the weekly energy balance (residual feed intake). Blood sampling started before diet implementation and was repeated every 2 weeks until Day 60 postpartum and then once monthly until Day 120. Plasma was kept at −20 °C until analysis for glucose, insulin and NEFA concentrations. Mixed linear models were used to analyse data (SAS 9.3; PROC MIXED). Holstein cows had lower mean energy balance than SRB cows (−4.7 ± 1.4 and −0.9 ± 1.4 MJ, respectively; p = 0.05). SRB cows had higher (p<0.001) BCS (3.3 ± 0.1) than Holstein cows (2.7 ± 0.1) and also higher plasma glucose concentrations from Day -30 to Day 120 relative to parturition (4.1 ± 0.1 and 4.2 ± 0.1 log ; mg/100 ml, respectively; p < 0.05). Overall, breed or diet had no effect on NEFA blood plasma concentrations. However, plasma NEFA concentration levels tended to be higher (p = 0.09) in SRB cows than in Holsteins at Day -14 before calving, indicating higher mobilisation of lipid from adipose tissue already before calving. In contrast, Holstein cows had higher NEFA at Day 14 postpartum than SRB cows (p < 0.05). There were no significant effects of diet or breed on reproductive performance (% pregnant at first AI, days open). However, commencement of luteal activity within 21d postpartum was affected (p < 0.05) by the interaction of breed and diet. These results suggest that Holstein cows prioritise milk production to a larger extent than SRB cows, resulting in a less balanced metabolic profile.

Introduction

In high-producing dairy cows, metabolic and reproductive disorders are gaining importance with the intensification of milk production [1], [2]. Genetic advances in combination with herd management strategies have succeeded in increasing milk production levels, but reproductive performance has been affected [3], [4], [5]. Fertility has been decreasing for more than 50 years, more so in Holstein cows than in the Swedish Red breed (SRB) [6], [7]. For Holstein cows, the pregnancy rate per AI decreased from 41% in 1998 to 38% in 2005, but in recent years this sharp decline in fertility in Holsteins has levelled out [8]. For SRB cows the decrease has been lower, from 43% to 41% [9], [10]. Holstein and SRB cows are the two major dairy breeds in Sweden [9].

For dairy cows, the beginning of lactation represents a stage of metabolic stress. During that time animals will have to adapt their high energy demands due to the rapid increase of milk production which will increase the energy requirements. A failure to meet those demands will lead to negative balance (NEB) [11]. The resulting NEB can have an effect on the reproductive potential of the affected cows [12], [13], [14].

Although many studies have examined the interaction between the somatotropic and the gonadotropic axis [15], [16], few have taken into consideration the variation between breeds in terms of nutrient prioritisation and the consequences of this variation on metabolism and reproductive performance [16], [17]. Plasma glucose and insulin concentrations are correlated [18], but are also associated with other hormones and metabolites, such as growth hormone and non-esterified fatty acids (NEFA) [19]. Correlations between the concentrations of blood metabolites and their association with physiology and diseases have been reported [20]. However, few studies have acknowledged that cows of different breeds may cope differently with negative energy balance [11].

The aim of this study was to investigate the effect of two feeding levels during the antepartum and postpartum period on reproductive performance. A set of blood metabolites (glucose, NEFA, insulin) was analysed in primiparous Holstein and SRB cows, in order to identify possible differences in the way these breeds adapt to negative energy balance after calving.