Rabbit Maternal Behavior: A Perspective from Behavioral Neuroendocrinology, Animal Production, and Psychobiology.

Rabbit maternal behavior (MB) impacts meat and fur production on the farm, survival of the species in the wild, and pet welfare. Specific characteristics of rabbit MB (i.e., three-step nest building process; single, brief, daily nursing bout) have been used as models for exploring particular themes in neuroscience, like obsessive-compulsive actions, circadian rhythms, and cognition. Particular hormonal combinations regulate nest building by acting on brain regions controlling MB in other mammals. Nonhormonal factors like type of lodging and the doe's social rank influence nursing and milk production. The concurrency of pregnancy and lactation, the display of nonselective nursing, and the rapid growth of altricial young - despite a minimal effort of maternal care - have prompted the study of mother-young affiliation, neurodevelopment, and weaning. Neurohormonal mechanisms, common to other mammals, plus additional strategies (perhaps unique to rabbits) allow the efficient, adaptive display of MB in multiple settings.

Assessing the Preference of Rabbit Does to Social Contact or Seclusion: Results of Different Investigations.

The aim of this study was to verify the motivation of rabbit does to social contact or seclusion. The results of two different research activities assessed in Italy (experiment 1) and Germany (experiment 2) through the use of motivational cages are reported. In experiment 1, only the average time of occupation of the group or seclusion zone was recorded of four nulliparous does, while, in experiment 2, the group-housing system provided space for does with kits and consisted of four single areas (nest boxes with individual electronic nest box recognition systems). Experiment 1 showed that does spent a similar amount of time in seclusion or in group (49.61% vs 50.39%, respectively). On the contrary, in experiment 2, does with kits appeared to prefer spending time alone (71.90%) rather than in groups. The presence of kits probably stimulates a hierarchical and aggressive response of the dominant does, with the low-ranking does staying secluded to avoid violent interactions. In fact, in each reproductive cycle, one doe did stay in the group area whereas the other three does used this area in different percentages of time. Further researches are needed to find a good combination of the cage with the does' physiological phases.

Investigations on the Influence of Floor Design on Dirtiness and Foot Pad Lesions in Growing Rabbits.

In Germany, an animal welfare ordinance for the housing of rabbits was issued which did not take into account the current investigations on floor design. The aim of the investigations was to study the effects of floor design on dirtiness and occurrence of lesions on the legs of growing rabbits. A total of 1837 weaned rabbits, kept on four different floor designs, were examined for body lesions and the dirtiness of the soles of the feet at the end of the growing period. Two four-stage scoring systems (0-3) were used to record the dirtiness and the lesions on the feet. A floor according to the provisions of the German animal protection ordinance (10 mm slat width; 50% perforation on floor area; <15% perforation on the elevated platform) led to the most polluted and injured rabbits. The best cleanliness and the lowest injury rate of the growing rabbits was achieved on a plastic floor with 5 mm slat width and 13 mm slot width, both on the ground and elevated platform (75% perforation). The requirements of the German housing regulations on the floor for growing rabbits do not correspond to animal welfare.

Voluntary locomotor activity promotes myogenic growth potential in domestic pigs.

Self-determined physical activity is an essential behavioural need and can vary considerably between individuals of a given species. Although locomotion is suggested as a prerequisite for adequate function of skeletal muscle, domestic pigs are usually reared under limited space allowance. The aim of our study was to investigate if a different voluntary locomotor activity leads to altered properties in the muscle structure, biochemistry and mRNA expression of selected genes involved in myogenesis and skeletal muscle metabolism. Based on a video tracking method, we assigned pigs to three categories according to their total distances walked over five observed time points: long distance, medium distance, and short distance. The microstructure and biochemistry parameters of the M. semitendinosus were unaffected by the distance categories. However, we found distance-dependent differences in the mRNA expression of the genes encoding growth (IGF2, EGF, MSTN) and transcription factors (MRF4, MYOD). In particular, the IGF2/MSTN ratio appears to be a sensitive indicator, at the molecular level, for the locomotor activity of individuals. Our results indicate that the myogenic growth potential of pigs under standard rearing conditions is triggered by their displayed voluntary locomotor activity, but the covered distances are insufficient to induce adaptive changes at the tissue level.

A new parameter describing fertility in rabbits at the farm level: the kit index.

The kit index (KI) combines the kindling rate (KR) and the average litter size (LS) per group of does, per breeding round, per year, or per farm and represents the number of total or live-born kits per 100 inseminated does. The KR is the percentage of kindlings per number of inseminated does. Mathematically, the KI is the product of the KR multiplied by the average LS. The KI was calculated on the basis of 12 730 inseminated does and 89 864 live-born kits from one rabbit farm during a 25-month period from 2015 to 2017. The average KR was 70.1 ± 9.1  % with a minimum (per breeding round) of 35.4 % and a maximum of 90.8 %. The average LS of total kits born was 9.16 ± 0.91 , whilst the average litter size of live-born kits was 8.87 ± 0.90 . The KI of total kits born was calculated to be 649 ± 121 kits per 100 inseminated does (min of 332, max of 971), while the KI of live-born kits ranged between 326 and 944 kits per 100 inseminated does (mean of 626 ± 122 ). The KI is a normally distributed parameter with respect to both the total kits born and the live-born kits per 100 inseminated does. All three parameters (KR, LS, and KI) were characterized by large variations from week to week with a tendency toward a reduction in the summer months. No difference was found between the two housing units, but large differences were found between the two genetic strains used on the given farm. Therefore, it can be concluded that the KI is able to characterize the complex fertility situation on the given rabbit farm. The KI can be used to demonstrate and to solve problems regarding artificial insemination, in addition to general issues with insemination management.

Effect of differently structured and processed feedstuffs on diverse parameters of ethology and digestibility of growing rabbits and their influence on morphological structures in small intestine.

The influence of different feedstuffs on parameters of digestion and ethology in growing rabbits (duration and number of feed intake, needed masticatory movements, pH value in stomach and small intestine, dry matter content of stomach chyme, level of destruction of cell structures in small intestine) was analysed. 384 five weeks old rabbits were fed with one of three feedstuffs: pellets (mean fibre length = 3 mm), fibre blocks (mean fibre length = 40 mm) and hay-oat-beat-ration (length of hay fibre ≥ 70 mm). The masticatory movements and duration for uptake 0.1 g of feedstuffs were measured in a special observation box. Rabbits in group cages were observed by 24 h video recording and duration and numbers of feed intakes were documented. After 8 weeks rabbits were slaughtered and pH values measured in stomach chyme (and dry matter content) and small intestine. Samples of them were taken and histologically examined (total length of villi and crypts, width of villi and degree of destruction determined by scores from 0 [= no destruction] to 3 [= severe destruction of villi]). Pellets lead to a faster feed intake with a lower number of masticatory movements. This equates a minor feeding time per feed intake and a higher amount of feedstuff in a shorter time. The dry matter content in stomach chyme increases and pH value was significantly higher there, but lower in duodenum. They also showed a significantly higher degree of destruction of villi, a shorter length and a larger width of villi than others.

[Effects of sorting weaner pigs by weight on growth performance, aggressive interactions and skin lesion score after mixing]. / Einflüsse einer Gewichtssortierung von Aufzuchtferkeln auf Lebendmasse- entwicklung, aggressive Auseinander- setzungen und Verletzungsgrad nach der Gruppierung.

Weaning piglets at the age of three or four weeks is an integral part of certain production rhythms in modern pig farming. Sorting piglets by weight and mixing them into new groups is a common method in agricultural practice. The aim of this study was to clarify whether the formation of homogeneous weight groups after weaning affects weight development and aggressive behaviour. We compared homogeneous and heterogeneous weight groups and entire litters that were weaned and reared completely. All groups including entire litters were composed of 12 animals. All piglets were weighed the day before weaning, four days later, and on day 38. The number of all aggressive interactions occurring within a group was determined by video analysis for 72 hours after mixing.There during four days after weaning or over the rearing period. Rearing entire litters resulted in significantly higher daily weight gain within four days after weaning and throughout the rearing period. Sorting piglets by weight did not affect the development of weight dispersion in a group. The coefficients of variation of weights in homogeneous and heterogeneous groups which differed significantly at the beginning were on a similar level after 38 days. Neither weight balance of piglet batches at the end of rearing nor growth performance or aggressive interactions were influenced by sorting piglets by weight at weaning.