Equipping Farrowing Pens with Straw Improves Maternal Behavior and Physiology of Min-Pig Hybrid Sows

Large litters have a detrimental impact on litter performance and postpartum maternal behaviour in primiparous sows

BACKGROUND

Our previous study confirmed that large litter size adversely affects prepartum maternal hormones and behaviour, concurrently with heightened oxidative stress in primiparous sows. The purpose of this study was to examine the effect of large litter size on litter performance, postpartum maternal behaviour, salivary cortisol levels, and colostral immunoglobulin levels in sows, as well as investigate their correlations with the levels of oxidative stress parameters.

RESULTS

A total of 24 primiparous sows (Landrace[Formula: see text]Large white) and their offspring were categorised into two groups based on litter size: NORMAL (n = 8) with litter size ranging from 7 to 14 (mean 11.5[Formula: see text]2.7), and LARGE (n=16) with litter size ranging from 15 to 20 (mean 15.9[Formula: see text]1.4). All sows were housed in a group housing system during gestation and transitioned to an adaptable loose housing system (2.4[Formula: see text]2.3 m) during the farrowing and lactation periods. The nursing and carefulness behaviour of the sows was monitored over a 24-h period between 72 and 96 h after parturition. Saliva samples were collected for cortisol assay on 35, 21, and 7 days before parturition (D-35, D-21, and D-7, respectively), as well as on days 1, 7, and 28 after parturition (D1, D7, and D28, respectively). On D1, higher piglet mortality rates were observed among the LARGE group compared to the NORMAL group (p<0.01). The total and successful nursing behaviours of the sows were less frequent in the LARGE group than in the NORMAL group (p<0.05, for both), and the carefulness score of the LARGE group was also lower than that of the NORMAL group (p< 0.01). On D1, cortisol levels in LARGE sows were higher than those in NORMAL sows (p< 0.05), and for other time points (D-21, D-7, D7, and D28), cortisol levels in LARGE sows tended to be higher than those in NORMAL sows (p < 0.10, for all). Successful nursing behaviour displayed negative correlations with levels of salivary cortisol and certain oxidative stress parameters measured on D1.

CONCLUSIONS

These findings suggest that the strategy for alleviating physiological and oxidative stress during the peripartum periods could benefit potential postpartum maternal behaviour and litter performance in the sows with large litters.

Effects of free farrowing system on the productive performance and welfare of sows and piglets

Regardless of international animal welfare regulations, most sows in production currently spend most of their lives and the peripartum period in caged housing systems. Although this type of management is intended to reduce neonatal mortality in piglets, several studies consider that there has been no significant reduction in its incidence over the last 30 years. On the contrary, cage housing has promoted the appearance of alterations during the farrowing process such as dystocia, as well as in maternal behavior and health, promoting stereotypes, skin lesions and other alterations, which not only impact the sows but also their progeny during the lactational period. Therefore, the aim of the present review is to compare the productive performance and welfare of sows and their piglets within the farrowing, lactation, and post-weaning period in both traditional and free-farrowing systems, highlighting the differences in these indicators in each of them.

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 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.

The Role of Oxytocin in Domestic Animal’s Maternal Care: Parturition, Bonding, and Lactation

Oxytocin (OXT) is one of the essential hormones in the birth process; however, estradiol, prolactin, cortisol, relaxin, connexin, and prostaglandin are also present. In addition to parturition, the functions in which OXT is also involved in mammals include the induction of maternal behavior, including imprinting and maternal care, social cognition, and affiliative behavior, which can affect allo-parental care. The present article aimed to analyze the role of OXT and the neurophysiologic regulation of this hormone during parturition, how it can promote or impair maternal behavior and bonding, and its importance in lactation in domestic animals.

An effective environmental enrichment framework for the continual improvement of production animal welfare

Substrates and objects are provided to farm animals on the assumption that they improve animal welfare by enriching the environment, but these often fail to consider the extent to which an environmental enrichment (EE) improves animal welfare, if at all. Furthermore, there are numerous definitions of EE, each with a unique expectation. If expectations of animal welfare improvement are set too high, industry uptake may be thwarted, but if thresholds are set too low it will not result in meaningful improvements to animal welfare. We propose an EE framework based on revised definitions of EE that reflect improvements to various components of animal welfare: (i) pseudo-enrichment; (ii) EE for meeting basic needs; (iii) EE for pleasure; and (iv) EE for positive welfare balance. This framework requires short- and long-term assessments to determine the impact of the EE, although many are lacking in the production animal literature. Redefining EE with a focus on specific animal welfare outcomes will assist producers in identifying the optimal EE for their enterprise. Subsequently, we encourage dialogue between farmers, researchers and industry stakeholders when designing environmental enrichment programmes. This framework is a science-based tool that can be used to inform the development of clear EE assessment protocols and requirements for animal welfare legislation, assurance programmes and industry. This evidence-based framework ensures that the focus is on the outcome of EE programmes rather than the intent. Importantly, this framework has the flexibility to adapt even as baseline environments evolve, ensuring the continual improvement to production animal welfare.

Emotional responses of piglets under long-term exposure to negative and positive auditory stimuli

The stress caused by sound is inevitable. The stress caused by noise and the positive effects of music can affect the endocrine of animals and their welfare. In this study, a total of 72 hybrid piglets (Large White × Duroc × Min pig) were randomly divided into 3 groups, including music (Mozart K.448, 60-70 dB), noise (recorded mechanical noise, 80-85 dB), and control (natural background sound, <40 dB) groups. S-IgA (secretory immunoglobulin A), IL-6 (interleukin-6), IL-8 (interleukin-8), and positive emotion-related behaviors were used as indicators to discuss whether noise induced stress and inflammation in piglets or whether music could have positive effects. Six hours of auditory exposure were given daily (10:00-16:00), which lasted for 56 days. Behavioral responses of the piglets were observed, and the concentrations of salivary S-IgA and serum IL-6 and IL-8 were measured. The results showed that the concentration of S-IgA increased in the noise and control groups on the 57th day (P < 0.05); S-IgA concentration in the music group was unchanged after long-term music exposure. The concentrations of IL-6 and IL-8 showed that long-term noise exposure might lead to stress and inflammation in piglets. Tail-wagging and play behaviors of the piglets in the music group were significantly greater than those in the noise and control groups, which implied that long-term music exposure improved the emotional state of the piglets in a restricted and barren environment.

Does Nursing Behaviour of Sows in Loose-Housing Pens Differ from That of Sows in Farrowing Pens with Crates?

Sows confined to farrowing crates are restricted in performing natural behaviour such as maternal behaviour. Loose-housing farrowing pens (LH) and farrowing pens with crates (FC) were compared regarding sows’ nursing behaviour via video analyses over four weeks per batch (one day per week). Nursing frequency was similar in LH and FC pens (1.25 ± 0.82 vs. 1.19 ± 0.75 nursings/sow/hour; p > 0.05). However, nursing duration differed between the two systems (LH: 5.7 ± 4.6 min vs. FC: 7.0 ± 5.0 min; odds ratio (OR) 1.168, p = 0.011). In LH pens, more nursing bouts were sow-terminated than in FC pens (OR 0.427, p = 0.001). The probability of sow-terminated nursing occurring increased from week 1 to week 4 (OR 3.479, adjusted p (padj) < 0.001), while that of observing unnursed piglets decreased from week 1 to week 4 (OR 0.301, padj < 0.001) and rose with increasing litter size (OR 1.174, p = 0.010). We conclude that nursing behaviour was affected by the farrowing system, with shorter nursing duration and more nursing terminations by the sow in LH than in FC pens. Since this corresponds to the nursing behaviour of sows in semi-natural conditions, it can be assumed that sows in LH pens are more likely to exhibit natural nursing behaviour.