Is the temperament of crossbred dairy cows related to milk cortisol and oxytocin concentrations, milk yield, and quality?

Abstract

Reactive dairy cows are more susceptible to stress, and this may result in negative effects on milk yield and quality. The aims of this study were to investigate the relationships between temperament traits and concentration of milk cortisol and oxytocin, milk yield, milkability, and milk quality in Holstein-Gyr cows. Temperament traits were assessed in 76 Holstein-Gyr cows in the milking parlor (by scoring milking reactivity and recording the numbers of steps and kicks during pre-milking udder preparation and when fitting the milking cluster) and during handling in the corral (by measuring the time to enter in the squeeze chute, ET and flight speed, FS). Milk samples were collected for milk quality (% fat, % protein, % lactose, and somatic cell count, SCC), and milk cortisol and oxytocin. Milk yield, milking time, and average flow were also measured. The calmer cows during milking management (class ‘low’) produced milk with higher protein (p = 0.028) content and tendencies for lower fat (p = 0.056) and higher lactose (p = 0.055) contents. Regarding the hormones, the most reactive cows (class ‘high’) in the milking and handling corral produced milk with higher concentrations of cortisol (p<0.001) and oxytocin (p = 0.023). In addition, the temperament of the animals affected some of the productive measures evaluated. Cows with reactive temperament had lower milk flow and longer milking time than the intermediate ones and had higher fat and a tendency for lower protein percentage in milk compared to cows with intermediate temperaments. Calm and intermediate cows in the handling corral produced more milk and presented better milkability parameters, such as a shorter milking time and greater average milk flow. Our results suggest that the cows’ behavioral reactivity can be related to the intensity of their response to stress during handling.

correlation of phenotypic, behavioral and biochemical variation with milk production and its components in cows

“…The most reactive cows during preparation for milking showed a decrease in the percentage of protein in the milk compared to the least reactive cows, as it recorded a rate of 3.17%, The results did not record any significant differences in the percentage of fat and lactose between the most and least reactive cows (Table 3) When the milking parts were installed on teats The udder The moderately reactive cows recorded an increase in the percentage of fat in the milk, as it recorded a percentage of 1.25% compared to the most and least reactive cows The results did not record any significant differences in the percentage of protein and lactose As for the cows that had more steps, the results recorded a significant increase in the protein percentage in the most and least reactive cows. interaction compared to moderately reactive cows, which recorded 3.30% and 3.31%, respectively, while the results did not record any significant differences in the percentage of fat, protein, and lactose in the cows with the most and the least number of kicks (Marçal-Pedroza et al, 2023). Calmer cows, as measured by the degree of reaction during milking preparation, produced milk with a higher protein content, while cows that were calmer while teat cups were tied tended to produce lower fat content ( Morales-Piñeyrúa et al, 2022) , and the temperament of the cows also affects the quality Milk: Cows that entered the milking parlor slowly tended to produce milk with a higher percentage of lactose compared to faster cows ( Kruszyński et al, 2013).…”

“…Oxytocin is the hormone responsible for milk supply and maintenance of lactation but has also been indicated As a physiological reaction to stressors (Hedlund and Løvlie,2015). In the study (Marçal-Pedroza et al, 2023), the milk of reactive cows contained higher concentrations of cortisol and oxytocin, which indicates that the high concentration of oxytocin may be part of the stress response in these cows, which are likely high in dealing with stress, and may This occurs as an attempt to mitigate the effects of stress during the milking process, as oxytocin has antistress effects. It is an anxiolytic, however, and a study Chen and Sato ( 2017) indicates that a high concentration of oxytocin in female rodents leads to a decrease in the concentration of cortisol The same thing happens in dairy cows that are accustomed to a new milking environment, where the There is an increase in the release of oxytocin as the cows get used to the new environment, accompanied by a decrease in the concentration of cortisol It was found that in the new milking environment (psychological stress), the concentration of cortisol in the blood was greater before milking, and the concentration of oxytocin was greater after milking.…”

“…a,b with different superscripts in the same column are significantly different. NS: Not significant *: P≤0.05; **: P≤0.01; Rsprep, degrees of reaction during pre-milking preparation, Rstca, degrees of reaction when installing the milking parts on the udder teats, Step, number of steps, Kicks, number of kicks( Marçal-Pedroza et al ., 2023( …”