Effect of social dominance on the meat quality of young Friesian bulls

Wound inflammation post-orchiectomy affects the social dynamic of Nelore bulls

BACKGROUND

Confinement of cattle imposes spatial restrictions and predisposes to aversive social encounters that can lead to contusions, wounds, pain, stress, fright, and reduced productivity. Although endogenous testosterone concentrations are linked to agonistic dominance behaviors in males, it is unknown whether decreased blood testosterone concentrations after castration alter social hierarchy rank in Nelore bulls. Therefore, in this study, we investigated the impact of the surgical would inflammation post-orchiectomy on social dynamics in a group of Nelore bulls (Bos indicus). Fourteen Nelore (Bos indicus) bulls were castrated and assessed pre- and post-surgically. Parameters evaluated were agonistic (mounting, headbutting, and fighting) and affiliative (head-play) behavior, plasma testosterone concentrations, average daily weight gain (ADG), and a score for severity of post-surgical infection. Exploratory statistics included social network analysis (SNA), hierarchy rank delta (Δ), and principal component analysis (PCA). Furthermore, statistical inferences included the Wilcoxon test, multiple logistic regression models, and Spearman's correlation.

RESULTS

The social dynamic of Nelore bulls was modified after castration based on the findings of the SNA and the PCA. The moderate correlation between the postoperative inflammation level with the Δ, and the significant effect of this level in the logistic model post-castration were partially attributed to effects of pain on social relations.

CONCLUSIONS

Our findings suggest the severity of post-surgical inflammation, which has an association with pain intensity, was closely associated with changes in the social hierarchy.

Heat Stress and an Immune Challenge Influence Turkey Meat Quality, but Conspecific-Directed Pecking Behavior Does Not

Heat stress (HS), immune challenges (IC) and pecking behavior are some of the many stressors poultry can experience in commercial settings that may affect bird welfare and meat quality after harvest. The first objective was to determine if HS or IC turkeys displayed greater negative effects on meat quality, and the second objective was to determine if the frequency of non-aggressive pecking behaviors among the birds was related to meat quality. Ninety-two, commercial male, beak-trimmed turkeys were used with a total of 15 rooms and 4–7 birds per room. Each treatment was applied for 1 week prior to harvest: the Control (CON) group had no stressors added, the HS group ambient temperature was approximately 29 °C for 120 min, and the IC group involved inoculating birds with a live vaccine for hemorrhagic enteritis virus. Birds were recorded and scored to quantify pecking behavior. Once harvested, carcasses were evaluated for feather retention force, pH, color, proximate analysis, fatty acid composition, shear force, and drip loss. Stress treatment resulted in HS breasts having the lowest protein content, and IC breasts having the lowest CIE L* values and the greatest shear force values. Pecking behavior had no impact on any meat quality attributes.

Stress, Subordination, and Anomalies of Feeding Across the Tree of Life: Implications for Interpreting Human Eating Disorders

Eating behaviors of animals living in naturalistic environments offer unique insights into several dysregulated eating patterns observed in humans. Social subordination is a known precipitant of hyperphagia and hypophagia in human beings, and examples of similar responses have been identified in a phylogenetically widespread range of vertebral species. This points to potentially conserved, patterned responses to animals navigating lives within social hierarchies. Self-imposed food restriction in subordinate fish and hyperphagic responses in socially subordinated bird and primate individuals may represent evolved adaptations to the stress of social subordination. As such, hyperphagic and hypophagic responses to social subordination in these species may model the natural history, neurobiology, and behavioral ecology of human dieting and bingeing more accurately than some current animal models. Phylogenetically widespread similarities in eating patterns under the stress of social subordination point to potentially shared biological benefits of these behaviors across species and the role of evolutionary trade-offs, adaptations, and other processes in shaping them. The application of a broadly comparative lens to disordered eating behaviors in other species exposes important similarities and differences between neurophysiology of eating across species. In doing so, it highlights the value of phylogenetic analyses and macroevolution as tools for identifying novel, naturally occurring models for understanding disordered human eating. Moreover, this approach introduces the intriguing possibility that human cultural influences on disordered eating may have far more ancient origins than previously considered.

The Effect of Behaviour and Diet on the Rumen Temperature of Holstein Bulls

Rumen temperature boluses are becoming increasingly used as a means of monitoring core body temperature for the detection of ill health. However, the effect of behavior on rumen temperature is largely unknown. This research investigates the impact of behaviour and diet on the rumen temperature of Holstein bulls, both at grass, and in a housed environment. Rumen temperature was recorded at five-minute intervals using a bolus. Direct observations were conducted on young bulls in two studies (i) at grass (n = 30) and (ii) while housed (n = 32). In addition, activity monitors were attached to bulls at grass (n = 24). Within each study, diet differed by the level of concentrate supplementation. There was no effect of diet on rumen temperature. Significant differences in rumen temperature were observed between behaviour groups for bulls at grass (p < 0.001) and housed (p < 0.001). Furthermore, drinking resulted in the lowest rumen temperature (grass 35.97 °C; housed 36.70 °C). Therefore, rumen temperature is affected by behavior; however, the temperatures recorded were not outside the normal temperature range for healthy cattle.

Computer vision and remote sensing to assess physiological responses of cattle to pre-slaughter stress, and its impact on beef quality: A review

Pre-slaughter stress is well-known to affect meat quality of beef carcasses and methods have been developed to assess this stress. However, development of more practical and less invasive methods are required in order to assess the response of cattle to pre-slaughter stressors, which will potentially also assist with the prediction of beef quality. This review outlines the importance of pre-slaughter stress as well as existing and emerging technologies for quantification of the pre-slaughter stress. The review includes; i) indicators of meat quality and how they are affected by pre-slaughter stress in cattle, ii) contact techniques that have been commonly used to measure stress indicators in animals, iii) remotely sensed imagery techniques recently used as non-invasive methods to monitor physiological and behavioural parameters and iv) potential implementation of remotely sensed imagery data to perform contactless assessment of physiological measurements, which could be related to the pre-slaughter stress, as well as to the indicators of beef quality. Relevance to industry, conclusions and recommendations for research are included.

Factors influencing the priority of access to food and their effects on the carcass traits for Japanese Black (Wagyu) cattle

The factors influencing the priority of access to food and the effects of the priority of access to food on their carcass traits were analyzed for Japanese Black (Wagyu) cattle in a semi-intensive fattening production system. The records of 96 clinically healthy steers and heifers were analyzed. The calves at ∼3 to 4 months of age were allocated to pens with four animals per pen; all four animals in the same pen were of the same sex and of similar body size. The ranking of the animals' priority of access to food (1st, 2nd, 3rd and 4th), which was determined by the farm manager, was used as an indicator of social dominance in the present study. Four models including sire line, maternal grandsire line and the difference in the animals' birth dates as fixed effects were used to analyze factors influencing the priority of access to food. Ranking was represented by ordinal scores (highest=4, lowest=1) in Model 1, and the binary scores were assigned in Model 2 (highest=1; 2nd, 3rd and 4th=0), Model 3 (1st and 2nd=1; 3rd and 4th=0) and Model 4 (1st, 2nd and 3rd=1; lowest=0). The results showed that the difference in the animals' birth dates had a significant effect on the establishment of the priority of access to food in Model 3 (P<0.05), suggesting that animals born earlier may become more dominant in the pen. The maternal grandsire line tended to affect the social rank score in Models 2 and 3 (P<0.10). Our results indicated that the maternal grandsire line may affect the temperament of calves through their mothers' genetic performance and thereby more aggressive calves may be more dominant and have higher priority of access to food. On the other hand, there was a significant effect of the priority of access to food on beef marbling score (BMS; P<0.05), and the priority of access to food also tended to influence the carcass weight (P=0.09). The highest BMS was observed for animals with the first rank of the priority of access to food (P<0.05), and the higher-ranking animals had the tendency to be heavier carcass than the lower-ranking animals. Our findings emphasized the importance of information about the priority of access to food determined by farmers' own observation on implementing best management practices in small-scaled semi-intensive beef cattle production systems.

Effect of the type of dietary fat when added as an energy source on animal performance, carcass characteristics and meat quality of intensively reared Friesian steers

The effects of different fats in the diet were evaluated on the basis of animal performance, carcass and meat-quality traits. Four groups of eight Friesian steers were intensively finished with concentrate and cereal straw given ad libitum. Four different types of fats were included at a 4% level in the diet, namely, palm oil, sunflower oil, tallow and hydrogenated fat. The feeding trial lasted for 84 days. There were no differences on animal performance or carcass characteristics, except for animals from the hydrogenated-fat diet, which had the greatest percentage of muscle and moisture, and the lowest percentage of fat in a 6th rib dissection. Meat colour, texture, lipid oxidation and consumer acceptability did not differ among the diets. Nevertheless, the effects of ageing or display time were more important than those of the source of fat. Intramuscular fatty acid profile was hardly influenced by the fat source. In conclusion, the type of fat added at the final stage of the rearing process, at a 4% of inclusion level, did not produce noticeable variations on productive parameters or product quality. This would allow to formulate rations for cattle, using the most profitable source of fat (added at low levels), without having variability on the product quality.

Lateralization of behavior in dairy cows in response to conspecifics and novel persons

The right brain hemisphere, connected to the left eye, coordinates fight and flight behaviors in a wide variety of vertebrate species. We investigated whether left eye vision predominates in dairy cows' interactions with other cows and humans, and whether dominance status affects the extent of visual lateralization. Although we found no overall lateralization of eye use to view other cows during interactions, cows that were submissive in an interaction were more likely to use their left eye to view a dominant animal. Both subordinate and older cows were more likely to use their left eye to view other cattle during interactions. Cows that predominantly used their left eye during aggressive interactions were more likely to use their left eye to view a person in unfamiliar clothing in the middle of a track by passing them on the right side. However, a person in familiar clothing was viewed predominantly with the right eye when they passed mainly on the left side. Cows predominantly using their left eyes in cow-to-cow interactions showed more overt responses to restraint in a crush compared with cows who predominantly used their right eyes during interactions (crush scores: left eye users 7.9, right eye users 6.4, standard error of the difference=0.72). Thus, interactions between 2 cows and between cows and people were visually lateralized, with losing and subordinate cows being more likely to use their left eyes to view winning and dominant cattle and unfamiliar humans.

Effects of castration age, dietary protein level and lysine/methionine ratio on animal performance, carcass and meat quality of Friesian steers intensively reared

The effects of castration age, dietary protein level and the dietary lysine/methionine (lys/met) ratio on animal performance, carcass characteristics and meat quality were studied in 64 intensively reared Friesian steers. Animals underwent castration procedures at 15 days old or at 5 months old. Dietary treatments started at 90 days old, with eight animals from each castration age randomly allocated to each treatment: 14.6% v. 16.8% CP (DM basis), and 3.0 v. 3.4 lys/met, on a 2×2×2 design. The recommended ratio of 3.0 was reached with supplementation of protected methionine. Steers were slaughtered at 443.5±26.2 kg live weight when they reached 12 months old approximately. Average daily gain, cold carcass weight or carcass classification were not affected by any studied effect. Muscle moisture (P=0.024), C18:2n-6 percentage (P=0.047), polyunsaturated fatty acid/saturated fatty acid (P=0.049) and n-6/n-3 (P=0.003) were higher in late castrated animals. Both high levels of dietary protein (P=0.008) and lys/met ratio (P=0.048) increased the percentage of muscle in the carcass. A level of 16.8% of CP in the diet also increased the percentage of monounsaturated fatty acids in the intramuscular fat (P=0.032), whereas a ratio lys/met of 3.4 decreased the percentage of saturated fatty acids (P=0.028). Thus, it is recommended using diets with a high protein level (16.8%) and a high lys/met ratio (3.4) in animals slaughtered at a young age, in order to obtain carcasses with high muscle content without negatively affecting productive traits or intramuscular fat composition.

The Effects of Pre-slaughter Stress and Season on the Activity of Plasma Creatine Kinase and Mutton Quality from Different Sheep Breeds Slaughtered at a Smallholder Abattoir

The objective of the current study was to determine the effect of pre-slaughter stress, season and breed on the activity of plasma creatine kinase (CK) and the quality of mutton. One hundred and seventy-three (173) castrated sheep from Dormer (DM), South African Mutton Merino (SAMM), Dorper (DP) and Blackhead Persian (BP) sheep breeds were used in the study. The animals were grouped according to age-groups as follows: Group 1 (6 to 8 months), Group 2 (9 to 12 months) and Group 3 (13 to 16 months). Blood samples were collected during exsanguinations using disposable vacutainer tubes for CK analysis. Representative samples of the Muscularis longissimuss thoracis et. lumborum (LTL) were collected from 84 castrated sheep, of different breeds (28 per breed) 24 h after slaughter. The following physico-chemical characteristics of mutton were determined; meat pH (pH24), color (L*, a* and b*), thawing and cooking losses and Warner Braztler Shear Force (WBSF). The activity of plasma CK was significantly higher (p<0.001) in summer (1,026.3±105.06) and lower in winter (723.3±77.75). There were higher values for L* (33.7±0.94), b* (11.5±0.48) and WBSF (29.5±1.46) in summer season than in winter season; L* (29.4±0.64), b* (10.2±0.33) and WBSF (21.2±0.99). The activity of plasma CK was influenced by the type of breed with Dormer having the highest (p>0.001) levels (1,358.6±191.08) of CK. South African Mutton Merino had higher values for pH24 (5.9±0.06), L* (34.2±0.97), b* (12.2±0.50) and WBSF (26.8±1.51) and Blackhead Persian had higher values (35.5±2.17) for cooking loss (CL%) than the other breeds. Computed Principal Component Analyses (PCA) on the activity of plasma CK and physico-chemical characteristics of mutton revealed no correlations between these variables. However, positive correlations were observed between pH24, L*, a*, b*, CL% and WBSF. Relationships between pre-slaughter stress, CK activity and physico-chemical characteristics of mutton were also observed. It was therefore concluded that although mutton quality and creatine kinase were not related, pre-slaughter stress, season and breed affected the activity of creatine kinase and mutton quality.