Combined production of free-range pigs and energy crops—animal behaviour and crop damages

Odor exploration behavior of the domestic pig (Sus scrofa) as indicator of enriching properties of odors

Introduction and aim

Although the sense of smell in pigs is widely recognized as being highly developed, surprisingly little is known about their sensory ability. This study aimed to (a) identify which non-social odors pigs were able to detect and distinguish between, (b) investigate the types of behavior expressed when exploring odors and, (c) compare pigs' responses to the different odors to evaluate their interest in the odors.

Methods

Growing pigs (N = 192) of crossbred commercial breeds were enrolled in the experiment (32-110 days of age, weighing 64.9 ± 10.1kg). Littermate pairs of opposite sex were tested in test pens with two odor insertion points in the pen wall, 55 cm apart. All pigs were habituated to the test pens and experimenters. Twelve odors were tested (eight essential oils and four synthetic perfumes) in groups of three odors, with each pig pair tested once with one set of three odors (all possible orders of the three odors were tested on 24 pairs in total), always against a non-odor control (demineralized water). In a test, each of the three odors were presented during three trials in a row (a total of 9 trials per test; trial duration: 1 min; inter-trial breaks: 2 min; total test duration: 25 min). Response variables included: duration of sniffing, feeding-related behavior (licking, biting and rooting), agonistic behavior (biting, displacement and pushing) and no approach of the odor or control, recorded throughout each 1-min odor presentation.

Results

All pigs sniffed an odor less when repeatedly presented (LMM: all odors P < 0.05), and significantly longer at the subsequent presentation of a new odor [LMM (3rd vs. 1st presentations): P < 0.001]. Specific odor and odor type (essential oil vs. synthetic perfume) had no significant effect on sniffing duration. Overall, feeding-related behavior and agonistic behavior were expressed significantly more when pigs explored the odor compared with the control insertion point (Paired t-tests: P < 0.001), and specific odor only affected the expression of feeding-related behavior.

Conclusion

Collectively, pigs express sniffing, agonistic, and feeding-related behavior when exploring odors, which suggests that pigs perceive odors of non-social origin as a resource. Odors may thus constitute relevant enrichment material for pigs.

Environmental and Management Factors Affecting the Time Budgets of Free-Ranging Iberian Pigs Reared in Spain

Simple Summary

Understanding the natural behaviour of pigs in free-range conditions facilitates the interpretation of their behaviour in intensive conditions. The present study aims to study behavioural indicators of activity in the domestic pig, reared free-range and under two feeding regimes, with some help from humans with concentrates and without help, just eating natural resources. Results confirmed that exploratory behaviour was an important behaviour for pigs, but the same animals that dedicated 50% of their time to this activity when they were not fed by humans reduced this activity to 17.8% when they were fed with concentrates. In addition, few social contacts between animals were seen in extensive conditions, with a higher incidence of negative rather than positive social behaviour. It was concluded that: (1) the need for exploring the surroundings in natural environments is of less importance for pigs when they are fed by humans, and (2) bathing areas in outdoor conditions are important for pigs in the event of warm conditions. Overall, it is concluded that natural behaviour of pigs in free-range conditions, such as a reduced foraging behaviour when pigs are fed with concentrates, should be considered when interpreting behavioural needs in intensive conditions.

Abstract

Understanding the natural behaviour of pigs in free-range conditions facilitates interpretation of their behaviour in intensive conditions. Studying six different farms over two years at different seasons, with climatic and management variations, allowed for a general description of Iberian pig behaviour and which factors have an influence on it. The main activity found was resting (56.5% of the time observed), followed by exploratory behaviour. However, this exploratory behaviour was higher when animals were fed only with natural resources than when fed with concentrates (50% versus 17.8%, respectively). In addition, pigs used bathing areas in summer that were not visited in winter. Negative social behaviour was seen more frequently than positive social behaviour, accounting, in total, for 1% of the total activity of animals. Pigs situated at the centre of the groups tended to remain more relaxed, while the peripheral animals remained more alert and vigilant. Our results indicate that foraging behaviour accounts for a significant proportion of pigs’ active time, but this proportion is much more reduced when pigs are fed concentrates. Therefore, behavioural needs in pigs reared in intensive conditions should consider that exploratory behaviour is reduced when pigs are fed with concentrates.

Spatial distribution of soil phosphorous fractions following 1-year farrowing sows in an outdoor hog-rearing farm in Eastern Canada

Outdoor hog-rearing operations are of interest for both producers and consumers due to high product quality, animal welfare status, and low input and potential environmental risks. However, hog manure is rich in phosphorus (P), an environmentally sensitive nutrient, and distribution of different P fractions down the soil profile in these production systems is not well understood. The objective of this study was to determine the spatial variability of soil P in different soil depth intervals following 1-year outdoor farrowing sows in a 0.5-ha paddock in cold-temperate climate of Eastern Canada. Soil samples were collected with 0-15, 15-30, and > 30 cm depth intervals (up to 60 cm or the depth that sampling was possible) in grazing/rooting, feeding, wallow, and farrowing hut areas. Soil samples were analyzed for Olsen P (P_ol), organic P (P_O), and total P (P_T). Areas with more frequent presence of hogs showed 45-80% greater P_ol concentrations, and movement of soluble P_O down the soil profile was higher in these areas compared with the grazing/rooting area. The P_O formed 80% of P_T throughout the paddock, and the spatial distribution of P_O was similar to P_T in all soil depth intervals but different from P_ol. Results also showed that P_O concentrations in the paddock decreased at > 30 cm depth except for the feeding area. Findings of this study reveal that farrowing sow cycle in an outdoor hog-rearing farm setting can result in hot spots of P, which enhance the risk of environmental pollution.

Effect of poplar trees on nitrogen and water balance in outdoor pig production - A case study in Denmark

Nitrate leaching from outdoor pig production is a long-standing environmental problem for surface and groundwater pollution. In this study, the effects of inclusion of poplar trees in paddocks for lactating sows on nitrogen (N) balances were studied for an organic pig farm in Denmark. Vegetation conditions, soil water and nitrate dynamics were measured in poplar and grass zones of paddocks belonging to main treatments: access to trees (AT), no access to trees (NAT) and a control without trees (NT), during the hydrological year April 2015 to April 2016. Soil water drainage for each zone, simulated by two simulation models (CoupModel and Daisy), was used to estimate nitrate leaching from the zones in each paddock. N balances (input minus output) for the treatments were computed and compared. The results showed that, in terms of annual water balance and regardless of treatment, simulated evapotranspiration of poplar was 560-569 and 489-498 mm for CoupModel and Daisy, respectively, and corresponding evapotranspiration of grass-clover was 250 and 400 mm, against precipitation of 1076 mm. Simulated drainage below the root zone varied as 620-723 mm for Daisy and 568-958 mm for CoupModel, the higher end of the latter being probably overestimated. Annual nitrate leaching ranged from 32 kg N ha^-1 in the poplar zone of NAT up to 289 kg N ha^-1 in the control grass zone of NT. The poplar zone showed significantly lower nitrate leaching, by 75-80%, compared to the grass zone. For the control NT treatment, nitrate leaching was approximately 50% higher in the grass zone closest to the hut compared to the grass zone further away. NT treatment also had the largest surface N balance of 468 kg N ha^-1 compared to 436 and 397 kg N ha^-1 for AT and NAT, respectively. When N losses by leaching and volatilisation were included, soil N balances were 118, 157 and 113 kg N ha^-1 for AT, NAT and NT, respectively. Overall, the two simulation models were found useful tools for analyses of water balance for complex agroforestry systems. The findings collectively suggest that it is possible to decrease nitrate leaching from outdoor pig production on sandy soils by inclusion of poplar trees. Additional measures are nevertheless needed to reduce N losses on a mean area basis in paddocks with 20% tree cover.

Foraging behaviour, nutrient intake from pasture and performance of free-range growing pigs in relation to feed CP level in two organic cropping systems

In organic pig production one of the major challenges is to be able to fulfil amino acid requirements based on organic and locally grown protein feed crops. The pig is an opportunistic omnivore with a unique capacity for foraging above and below the soil surface. It is hypothesized that direct foraging in the range area can pose an important contribution in terms of fulfilling nutrient requirements of growing pigs. Foraging activity, lucerne nutrient intake and pig performance were investigated in 36 growing pigs, foraging on lucerne or grass and fed either a standard organic pelleted feed mixture (HP: high protein) or a grain mixture containing 48% less CP (LP: low protein) compared with the high protein feed mixture, from an average live weight of 58 kg to 90 kg in a complete block design in three replicates. The pigs were fed 80% of energy recommendations and had access to 4 m2 of pasture/pig per day during the 40 days experimental period from September to October 2013. Behavioural observations were carried out 12 times over the entire experimental period. For both crops, LP pigs rooted significantly more compared with HP pigs but the effect of CP level was more pronounced in grass (44% v. 19% of all observations) compared with lucerne (28% v. 16% of all observations). Feed protein level turned out not to have any significant effect on grazing behaviour but pigs foraging on lucerne grazed significantly more than pigs foraging on grass (10% v. 4% of all observations). Daily weight gain and feed conversion ratio were significantly affected by feed protein and forage crop interactions. Compared to HP pigs, LP treated pigs had 33% lower daily weight gain (589 v. 878 g) and 31% poorer feed conversion ratio (3.75 v. 2.59 kg feed/kg weight gain) in grass paddocks, whereas in lucerne paddocks LP pigs only had 18% lower daily weight gain (741 v. 900 g) and a 14% poorer feed conversion ratio (2.95 v. 2.54 kg feed/kg weight gain) compared with HP pigs. LP pigs foraging on lucerne used 169 g less concentrate CP/kg weight gain, compared with HP pigs, indicating the nitrogen efficiency of the system. The results indicate that direct foraging of lucerne may be a valuable strategy in terms of accommodating CP and lysine requirements of organic growing pigs.

Development of automatic surveillance of animal behaviour and welfare using image analysis and machine learned segmentation technique

In this paper the feasibility to extract the proportion of pigs located in different areas of a pig pen by advanced image analysis technique is explored and discussed for possible applications. For example, pigs generally locate themselves in the wet dunging area at high ambient temperatures in order to avoid heat stress, as wetting the body surface is the major path to dissipate the heat by evaporation. Thus, the portion of pigs in the dunging area and resting area, respectively, could be used as an indicator of failure of controlling the climate in the pig environment as pigs are not supposed to rest in the dunging area. The computer vision methodology utilizes a learning based segmentation approach using several features extracted from the image. The learning based approach applied is based on extended state-of-the-art features in combination with a structured prediction framework based on a logistic regression solver using elastic net regularization. In addition, the method is able to produce a probability per pixel rather than form a hard decision. This overcomes some of the limitations found in a setup using grey-scale information only. The pig pen is a difficult imaging environment because of challenging lighting conditions like shadows, poor lighting and poor contrast between pig and background. In order to test practical conditions, a pen containing nine young pigs was filmed from a top view perspective by an Axis M3006 camera with a resolution of 640 × 480 in three, 10-min sessions under different lighting conditions. The results indicate that a learning based method improves, in comparison with greyscale methods, the possibility to reliable identify proportions of pigs in different areas of the pen. Pigs with a changed behaviour (location) in the pen may indicate changed climate conditions. Changed individual behaviour may also indicate inferior health or acute illness.