Energy Balance Indicators during the Transition Period and Early Lactation of Purebred Holstein and Simmental Cows and Their Crosses

SIMPLE SUMMARY: Dairy cows undergo a very challenging time between the weeks immediately before calving and the start of lactation after calving. In particular, high yielding dairy cows, such as purebred Holstein cows, have to cope with a severe negative energy balance. In comparison to the feed (energy) intake, they produce a great surplus of milk energy. The energy deficit is supposed to be smaller in dual-purpose breeds, such as (German) Simmental. Therefore, crossbreeding of both breeds, with the aim of using the advantageous characteristics of both breeds, and the expected advantage of crossbred cows, might reduce the negative effects of the metabolic and physiologic challenges by improving the production efficiency of dairy herds. After calving, Simmental cows and cows with greater Simmental proportions decreased less in the body condition score, had lower concentrations of ketone bodies, and nonesterified fatty acids in the blood, which are common indicators of metabolic disorders during the transition period. In particular, first generation (F1) crossbred cows produced more energy corrected milk (ECM) than purebred Holstein cows, while the other crossbred generations still showed positive heterosis effects for ECM. That means, they produced more ECM than the average of both parental breeds. ABSTRACT: Crossbreeding in dairy cattle has been used to improve functional traits, milk composition, and efficiency of Holstein herds. The objective of the study was to compare indicators of the metabolic energy balance, nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), glucose, body condition score (BCS) back fat thickness (BFT), as well as milk yield and milk composition of Holstein and Simmental cows, and their crosses from the prepartum period until the 100th day of lactation at the Livestock Center of the Ludwig Maximilians University (Munich, Germany). In total, 164 cows formed five genetic groups according to their theoretic proportion of Holstein and Simmental genes as follows: Holstein (100% Holstein; n = 9), R1-Hol (51–99% Holstein; n = 30), first generation (F1) crossbreds (50% Holstein, 50% Simmental; n = 17), R1-Sim (1–49% Holstein; n = 81) and Simmental (100% Simmental; n = 27). The study took place between April 2018 and August 2019. BCS, BFT blood parameters, such as BHBA, glucose, and NEFA were recorded weekly. A mixed model analysis with fixed effects breed, week (relative to calving), the interaction of breed and week, parity, calving year, calving season, milking season, and the repeated measure effect of cow was used. BCS increased with the Simmental proportion. All genetic groups lost BCS and BFT after calving. Simmental cows showed lower NEFA values. BHBA and glucose did not differ among genetic groups, but they differed depending on the week relative to calving. Simmental and R1-Sim cows showed a smaller effect than the other genetic groups regarding changes in body weight, BCS, or back fat thickness after a period of a negative energy balance after calving. There was no significant difference for milk yield among genetic groups, although Simmental cows showed a lower milk yield after the third week after calving. Generally, Simmental and R1-Simmental cows seemed to deal better with a negative energy balance after calving than purebred Holstein and the other crossbred lines. Based on a positive heterosis effect of 10.06% for energy corrected milk (ECM), the F1, however, was the most efficient crossbred line.