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The aim of the study was to evaluate the effect of total mixed ration particle size (length) and breed of cow on intake dynamics, animal performance and CH 4 emissions, comparing high yielding Holstein and low yielding Girolando cows. The experimental design was 2 × 2 Latin Square arranged as a crossover factorial scheme with two diets (short particle size, SPS and long particle size, LPS) and the two breed compositions. The design comprised two periods of 26 d each, where all data collection was performed at cow level. No influence of the particle size occurred for the passage rate, neutral detergent fiber digestibility, performance and milk composition, methane emissions or ruminal fermentation parameters. Girolando cows had greater dry matter intake (DMI) when fed SPS, while Holsteins had the same ( P < 0.05). Girolando cows had lower dry matter digestibility when fed LPS compared to SPS, while Holsteins had the opposite effect ( P < 0.05). Also, the digestibility of crude protein and non-fibrous carbohydrates decreased in Girolando cows fed LPS, but not in Holsteins ( P < 0.05). Girolando cows reduced DMI by 10.6% when fed LPS diet ( P < 0.05). Girolando had an increased eating rate (+24 g of DM/min; P < 0.05) compared to Holstein cows, but Holstein cows had a lower CH 4 intensity (by 29.7%: P < 0.05). Girolando cows increased the dry matter intake when fed a diet with short particle size, while the same did not happen in Holsteins. Dry matter digestibility increased in Holsteins when fed long particle size, while the opposite was observed in Girolando cows. Nutrient digestibility was reduced in Girolando cows when fed short particle size. Particle size did not influence eating time, eating rate, feed trough visits, visits with intake, milk yield and composition regardless of the breed. Reducing particle size increased CH 4 intensity in both breeds.

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., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Marçal-Pedroza et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The objective of this study was to evaluate the production, consumption, and energy balance parameters of primiparous 3/4 and 7/8 Holstein × Gir (HG) dairy cows fed two diets of differing energy levels during the postpartum period. At the beginning of the study, 28 days prepartum, the average weight of both genetic groups was 498 ± 12 kg and body condition score (BCS) was 3.5 ± 0.05. At the end of the study, 61 days postpartum, the 3/4 HG cows had higher weight and body condition scores than the 7/8 HG (456 ± 8 and 429 ± 8 kg and 3.13 ± 0.03 and 2.94 ± 0.03 BCS for 3/4 HG and 7/8 HG, respectively). Milk from cows fed the high-energy diet had higher percentages of fat, protein, lactose, and total dry extract than cows fed the low-energy diet. Cows fed the high-energy diet had higher net energy intake (95.3 ± 1.9 vs. 88.1 ± 2.1 MJ/day) and higher energy balance (3.64 ± 2.13 vs - 6.02 ± 2.30 MJ/day). The 3/4 HG cows displayed higher energy for maintenance (33.1 ± 0.4 MJ/day) than the 7/8 HG (31.5 ± 0.5 MJ /day). In conclusion, although the primiparous 3/4 HG were heavier than the 7/8 HG and had a higher body condition score, no differences in milk produced up to 60 days postpartum were observed. The higher energy diet during the postpartum period increased energy balance, resulting in higher production of milk fat, protein, and lactose.

Highlights • Hr-Tag rumination monitoring system was evaluated for calves at the weaning period. • There is a high correlation between Hr-Tag and real rumination time values. • Hr-Tag system can identify differences in rumination time among weaning periods. • Adjustments in Hr-Tag system are needed for lower rumination values. Abstract Rumination time is a relevant marker for health evaluation. The use of rumination monitoring systems can decrease labor costs when measuring rumination time. The objectives of this study were to: i) validate the Hr-Tag rumination monitoring system for estimating rumination time in Zebu calves during the weaning period and ii) to evaluate the Hr-Tag capacity to identify differences in daily rumination patterns during the weaning period. Thirty-two Gyr calves averaging 69 ± 7.6 kg body weight and 77.0 ± 4.0 days were used. Calves were fed 4.7 ± 0.5 L/day of whole milk and ad libitum commercial textured starter ration up to 83 days old (pre-weaning period). During the weaning period (84–86 days old) the same starter was used, but corn silage was also available and only half the milk dose was offered. After weaning (87–92 days old, post-weaning period) only corn silage and starter were used. For the Hr-Tag system validation, the rumination time obtained by Hr-Tag was compared with visual observations at four 2 h intervals (0600 to 0800, 0800 to 1000, 1400 to 1600, and 1600 to 1800 h) at pre- and post-weaning. Two observers were used in all visual evaluations. To compare daily rumination pattern at pre-weaning, weaning and post-weaning, only the Hr-Tag data was used. Rumination time values between observers were highly correlated (ρ = 0.956; P < 0.001). Visual and Hr-Tag rumination time did not follow a similar probability distribution (P < 0.001), but they were correlated (ρ = 0.702; P < 0.001). The Hr-Tag system overestimated rumination time, mainly when the calves had visual rumination activity close to or equal to zero. The Hr-Tag detected differences in rumination time between weaning periods (P < 0.05). In conclusion, the Hr-Tag system overestimates rumination time in weaning calves, mainly by recording nonexistent rumination. However, the Hr-Tag system recorded rumination values correlated to visual observations and detected differences in rumination activity among weaning periods. [ABSTRACT FROM AUTHOR]