Effect Of Environment On Productivity, Behaviour, And Physiological Indicators Of Pigs

Modern swine production is mainly intensive farming in China. Intensive farming brings in high yield and low labor cost, however, it violates the biological characteristics of swine, and leads to adverse physiological responses inevitably, triggering a number of diseases. Many problems of modern swine production are caused by the fact that animals can not adapt to their environment which results in comprehensive discomfort, so animal welfare is the way to healthy development of swine production in the future. Outdoor organic pig production system and enriched indoor pig production system are two main modes of welfare-based swine production. The enriched indoor pig production system is a combination of modern intensive feeding pattern and traditional extensive feeding, which is in full use of modern feeding facilities and technology while providing a rich feeding environment to meet pigs'behavioural and physical requirements, and canceling some treatment with injuries. The enriched indoor pig production system compared to intensive production performs favorably, in which the straw-bedded pen is the most common form.This study focused on current issues in swine production, combined with the biological characteristics of pigs and pig production features, designed straw-bedded pen and supporting feeding process for China's conditions. The core issue of this study was to find design parameters of the pen, because pigs have different needs at different stages, while parameters in intensive production system has no reference value, and the technical parameters of foreign countries are not completely suitable for conditions in China. This research focused on rationality of the design, by evaluating the welfare in straw-bedded pen comparing with conventional intensive pen. This study made an attempt to seek a new scientific farming mode, in order to establish a safe, effective, and welfare system of production suitable for China's national condition.Materials and MethodsExperiment 1-3 were consecutive. 16 gilts with closed EPD and their piglets were reared in straw-bedded farrowing pen or farrowing crate randomly.In experiment 1, nest-building, postures within 3 days after partuition, and bahaviour of gilts in 2-5 weeks after partuition were observed. Prolactin, cortisol, and IgG were measured at 2 days before EPD, the partuition day, and the weaning day.In experiment 2, coping characteristics of piglets were measured, and injury and death were recorded. Body weight at birth and at 1, 3 and 5 weeks of age were recorded. Bahaviour of piglets in 2-5 weeks after birth was observed in two 2-hours periods. Four piglets (2 male and 2 female) per litter were randomly selected to measure cortisol, growth hormone(GH) and IgG at weaning day.In experiment 3, weaning piglets from experiment 2 were chosed by weight, and reared in their original pen. Daily feed intake (DFI) and body weight at 6 weeks and 10 weeks of age were recorded. Bahaviour of piglets in 7-10 weeks of age was observed from 07:00 to 15:00. Four piglets (2 male and 2 female) per litter were randomly selected to measure cortisol, GH and IgG at 10 weeks of age.In experiment 4,156 piglets (female) at 74-78 days of age were selected from the same environment, and randomly moved to the straw-bedded pen or barren concrete pen after weighed. After a weeks pre-experiment, there was a 8-week experiment. Feed intake and weight at the end were recorded. The behaviour of growing pigs was observed in two 1-hour periods. Three piglets per litter were randomly selected to measure cortisol and GH before and after the experiment.ResultsExperiment 1: Straw-bedded pen can encourage gilts'nest-building behaviour, and reduced the incidence of abnormal behaviour, and their oral behaviour directed mostly to straw, while gilts in farrowing crate performed more ventral lying and sitting, and less lateral lying, and the frequency of their vacuum-chewing and active behaviour directed to pen were higher; gilts in straw-bedded pen performed more ventral lying, standing, walking and active behaviour in week 5 after farrowing, while gilts in farrowing crate performed less behaviour directed to pen in week 3 and week 4 than in week 2 and week 5; lower cortisol also showed that straw-bedded pen can reduce gilts'stress.Experiment 2: Straw-bedded pen can significantly reduce the post-natal piglets'leg injury and diarrhea within one week, however, their weight at 3 weeks of age and weaning age was lower, and ADG at 3 weeks of age was also lower; GH at weaning age was higher and cortisol concentration was lower.Straw-bedded pen can significantly reduce piglets'behaviour directed to penmates and pen, while piglets in farrowing crates had fewer walking and more lying, but more exploring, among which exploring directed to pen took larger proportion; weeks of age had no significant impact on piglets in farrowing pen, while 3 weeks of age was the peak of piglets'behaviour in straw-bedded pen, during this period of time suckling behaviour decreased; suckling piglets in both environment had a completely different behaviour rhythm: piglets in farrowing crate had fewer lying and walking during observing time in the afternoon than in the morning, all activity increased except suckling behaviour, while piglets in straw-bedded pen only had more suckling behaviour in the afternoon. Behaviour expressions of piglets with different adaption characteristic in straw-bedded pen were not significantly different, while in farrowing crates, social interaction, behaviour directed to penmates and non-suckling behaviour of HR piglets were more than those of LR piglets.Experiment 3: Piglets in straw-bedded pen had significantly fewer feed intake and less than piglets in slatted pen, weight gain from 50 days of age but higher growth hormone concentration.Straw-bedded pen can significantly reduce weaners'exploring behaviour directed to pen, increase walking, exploring and active behaviour, but it can not reduce exploring behaviour directed to penmates. Weaners at 8-10 weeks of age in straw-bedded pen had lees lying and more fighting; incident of fighting among piglets in slated pen peaked at 7 weeks of age, while occurred most at 9-10 weeks of age in straw-bedded pen. Piglets in slated pen had fewer exploring behaviour directed to pen, exploring behaviour and active behaviour with weeks of age increased, while piglets in straw-bedded pen had fewer exploring behaviour directed to pen with weeks of age increased, but the behaviour increased significantly at 10 weeks of age. Besides, environment had an impact on rhythm of behaviour except feeding. New straw replacement in the morning kept pigs in a more active status, and also made the trough of activity shorter, and the active level was higher than pigs in slated pen.Experiment 4: Straw-bedded pen had no significant effect on productivity of growing pigs, but can lower cortisol concentration and reduce exploring behaviour directed to pen, and increase active level of growing pigs. Although sitting behaviour was more, most was biting straw when sitting.Ventral lying, walking, standing, behaviour directed to penmates and exploring of growing pigs in barren pen decreased gradually with test weeks increased, while lateral lying firstly decreased and then increased gradually, the turning point is about week 5 in the test. Meanwhile pigs in barren pen had more lateral lying and total lying, and fewer ventral lying, standing, sitting, walking and total activity; pigs in straw-bedded pen were just the opposite. However, pigs in both environments performed more exploring directed to pen and penmates in the afternoon.Conclusion1. The straw-bedded farrowing pen reduced stress of gilt, and met the behavioural requirement. Straw stimulated nest-building behaviour, and effectively reduced the sitting, oral behaviour directed to pen and vacuum-chewing.2. The straw-bedded farrowing pen can significantly reduce piglets'leg injury and diarrhea in the first week after birth. Straw-bedded farrowing pen can effectively reduce exploring directed to pen or penmates, and avoid stress.3. Straw-bedded weaner pen reduced stress, and to some extent met the behavioural requirement of piglets. Piglets in Straw-bedded weaner pen had more active behaviour, more exploring, and fewer behaviour direct to pen.4. Straw-bedded growing pen with a small amount of straw can reduce behaviour directed to pen or penmates, and increase activity of growing pigs, reduced stress and had no negative impact on productivity.