Environmental enrichment in finishing pigs: does it promote any changes in bone biomechanics?

The resistance of pigs' bone structure was evaluated for the first time, reared with and without environmental enrichment (EE) in the finishing phase using techniques in bone biomechanics; 432 swine from the Hampshire breed, being males and females, with initial body weight between 22 and 27 kg and final body weight between 110 and 125 kg were evaluated for 112 days. The experimental design was in randomized blocks, with 6 treatments, distributed in a 2 × 3 factorial scheme (sex × conditions in creation), with 12 repetitions/treatment, totaling 72 pens. The treatments were as follows: branched chain for males (T1), sisal branched string for males (T2), males without EE (T3), branched chain for females (T4), sisal branched string for females (T5), and females without EE (T6). At the end of the experimental period, all animals were slaughtered in an industrial slaughterhouse, having their femur bones collected for bone biomechanics analysis. There was no effect (P > 0.05) of the interaction (enrichment × sex) and individual factors for bone weight. There was a tendency (P = 0.08) of the interaction for flexion force, being higher in males enriched with branched ropes and chains. For breaking stress, there was an interaction effect (P = 0.04), being the females without EE the ones showing the lowest breaking stress, favoring bone fragility. The use of branched ropes and chains strengthens the bone structure in swine in the termination phase (110-125 kg BW - 183-190 days in age), being an important strategy used to meet the animal welfare requirements.

Evaluation of environmental enrichment on thermophysical responses, carcass traits, and meat quality of finishing pigs

Environmental enrichment consists of a way to provide better living conditions for animals, but its influence on physical integrity, thermoregulatory responses, and quality of pork meat is not known. The objective of this study was to evaluate the thermoregulatory responses, lesion score, lameness, carcass traits, and meat quality of pigs with and without access to environmental enrichment (EE) in the finishing phase. A total of 432 pigs of the Hampshire lineage, males and females, with average initial and final weights between 22-27 kg and 110-125 kg respectively were evaluated. The experimental design used was in randomized blocks, with 6 treatments, distributed in a 2×3 factorial scheme (sex × environmental enrichment), with 12 repetitions per treatment, totaling 72 stalls. The treatments were branched chain for males (T1), branched sisal rope for males (T2), males without EE (T3), branched chain for females (T4), branched sisal rope for females (T5), and females without EE (T6). Weekly, two assessments of physiological data were performed, in loco, in the morning and afternoon. Lesions on the tail, ear, body, and lameness were evaluated on the 1st, 16th, 37th, 51st, 79th, 93rd, and 112th days. On the 112th day, 72 animals were slaughtered for carcass traits and meat quality analyses. Statistical analysis was performed using generalized and mixed linear models. There was no effect (p>0.05) of the interaction of the studied factors (environmental enrichment × sex × period) on the head, back, leg, and average temperature. However, there was an effect of the period factor (p<0.01), with higher temperatures in the afternoon compared to the morning. For tail injury, there was no association between injury degree and gender (p=0.56) and between injury degree and enrichment (p=0.99), and there was no interaction effect (p=0.15). For ear injury, there was no association between the degree of ear injury and gender (p=0.72), as well as for the degree of ear injury and enrichment (p=0.99) and interaction (p=0.47). There was a higher occurrence of categories 2, 3, and 4 for lesions on the body in males (p=0.0257), regardless of the EE. Water retention, carcass yield, cut yield, marbling pattern, pH, and color showed no effect for sex, enrichment, and interaction between the two factors (p>0.05). The use of environmental enrichment with sisal ropes and branched chains does not change the thermophysical responses, carcass traits, and meat quality of finishing pig.

Evaluation of environmental enrichment on productive and behavioral responses of finishing pigs

Productive and behavioral responses of finishing pigs with and without access to environmental enrichment (EE) were evaluated. A total of 432 pigs, male and female, Hampshire line, initial and final weight of 22-27 kg and 110-125 kg, respectively, were studied for 112 days. The study design was in random blocks, with 6 treatments, distributed in a factorial scheme 2 × 3 (sex × treatment) and 12 repetitions/treatment, totalling 72 pens. The animals were weighed and distributed in 3 blocks-light (20.3 to 24.8 kg), medium weight (24.8 to 27.7 kg), and heavy (27.7 to 33.8 kg). The treatments were as follows: branched chains for males (T₁); branched sisal ropes for males (T₂), males without EE (T₃); branched chains for females (T₄); branched sisal ropes for females (T₅) and females without EA (T₆). There was no effect (P > 0.05) of interaction (enrichment × sex) and sex on performance. Daily consumption and daily weight gain were lower (P < 0.05) in the chain group compared to the sisal rope and control groups. Feed conversion was similar (P > 0.05) between treatments under study. There was no interaction between gender and enrichment for behavioral responses (P = 0.8986). However, there was an environmental enrichment (P = 0.0017; P < 0.001) and gender (P = 0.0251; P < 0.001) effect in relation to the animals' behavior in the morning and in the afternoon, respectively. Calmer animals, regardless of sex, were observed for groups without enrichment (control) and morning and afternoon periods. The animals interacted with the types of enrichment under study, given the higher probabilities of interaction with the object for males and females in the morning and afternoon shifts. It was observed, regardless of the shifts, that the control treatment for males and females was different when compared to the other enrichments for males and females. In general, the pigs' behaviors were expressed more in the afternoon when compared to the morning. It was observed that the animal interaction and aggression (afternoon shift) behaviors are more related to the control group, while object interaction is more related to the enriched treatments. The use of sisal ropes and branched chains guarantees the performance and behavior of pigs in the finishing phase, but we recommend the use of branched chains, as this enrichment increased the profitability of the farmer by reducing feed consumption, maintaining feed conversion and animal welfare, besides being a more durable material than sisal rope.