A two-level pen for fattening pigs: Effects on behavior, performance, and postslaughter measurements

Welfare of pigs on farm

This scientific opinion focuses on the welfare of pigs on farm, and is based on literature and expert opinion. All pig categories were assessed: gilts and dry sows, farrowing and lactating sows, suckling piglets, weaners, rearing pigs and boars. The most relevant husbandry systems used in Europe are described. For each system, highly relevant welfare consequences were identified, as well as related animal-based measures (ABMs), and hazards leading to the welfare consequences. Moreover, measures to prevent or correct the hazards and/or mitigate the welfare consequences are recommended. Recommendations are also provided on quantitative or qualitative criteria to answer specific questions on the welfare of pigs related to tail biting and related to the European Citizen's Initiative 'End the Cage Age'. For example, the AHAW Panel recommends how to mitigate group stress when dry sows and gilts are grouped immediately after weaning or in early pregnancy. Results of a comparative qualitative assessment suggested that long-stemmed or long-cut straw, hay or haylage is the most suitable material for nest-building. A period of time will be needed for staff and animals to adapt to housing lactating sows and their piglets in farrowing pens (as opposed to crates) before achieving stable welfare outcomes. The panel recommends a minimum available space to the lactating sow to ensure piglet welfare (measured by live-born piglet mortality). Among the main risk factors for tail biting are space allowance, types of flooring, air quality, health status and diet composition, while weaning age was not associated directly with tail biting in later life. The relationship between the availability of space and growth rate, lying behaviour and tail biting in rearing pigs is quantified and presented. Finally, the panel suggests a set of ABMs to use at slaughter for monitoring on-farm welfare of cull sows and rearing pigs.

The Impact of Grouping on Skin Lesions and Meat Quality of Pig Carcasses

Simple Summary

In practice, unfamiliar pigs are frequently mixed prior to loading in order to obtain groups of uniform weight and to adjust the group size to the dimensions of the trailer compartments. Regrouping pigs is associated with establishing a new social rank via aggressive interactions. Fighting results in skin lesions and pre-slaughter stress, which leads to reduced meat quality. In this study, four grouping strategies, namely, non-regrouping and regrouping at fattening (regrouped at 80 kg and kept till slaughter), loading and lairage, were compared by determining skin lesions and meat quality at slaughter. The non-regrouped pigs showed, at slaughter, fewer skin lesions and better meat quality than the pigs regrouped at loading or in lairage. Pigs mixed at 80 kg at the farm have, in general, a comparable amount of skin lesions and comparable meat quality as the non-mixed group. If mixing is unavoidable, due to large within-group weight variations, mixing at 80 kg can be an alternative to reduce skin lesions at slaughter and to optimise meat quality. However, mixing at 80 kg is still associated with aggressive interactions after regrouping and with weight variations at slaughter.

Abstract

In practice, unfamiliar pigs are frequently mixed prior to loading in order to obtain groups of uniform weight and to adjust the group size to the dimensions of the trailer compartments. Mixing pigs induces aggressive interactions to establish a new social rank. Fighting results in skin lesions and pre-slaughter stress and, in turn, reduced meat quality. A study was performed to compare the effect of non-regrouping and regrouping at fattening (at 80 kg and kept till slaughter), loading and lairage. A total of 1332 pigs were included over 30 transports from one pig farm to one slaughterhouse (110 km). Skin lesions were determined on 1314 carcasses. Meat quality was measured on 620 pigs. The non-regrouped pigs had fewer skin lesions and better meat quality than the pigs regrouped at loading or in lairage. Pigs mixed at 80 kg at the farm had, in general, a comparable amount of skin lesions and comparable meat quality as the non-mixed group. If mixing is unavoidable, due to large within-group weight variations, mixing at 80 kg can be an alternative to reduce skin lesions at slaughter and to optimise meat quality.

A Review of the Effects of Non-Straw Enrichment on Tail Biting in Pigs

Simple Summary

Tail biting, a damaging behaviour that one pig directs at another, causes pain, wounding and health problems. It reduces both pig welfare and market value. Enrichment can reduce tail biting substantially. Many pig producers are reluctant to use straw as enrichment, but many non-straw alternatives exist. We aimed to evaluate their ability to reduce tail biting based on studies on the effects of enrichment on tail damage and manipulation of other pigs, and on the duration of interaction with enrichment. Additionally, we reviewed how pigs interact with different enrichments (e.g., by rooting or chewing it). This was done to clarify which type of enrichment could satisfy which behavioural motivation (that may lead to tail biting if not satisfied). However, very little information on separate enrichment-directed behaviours was uncovered. Several effective types of non-straw enrichment were identified, but these correspond poorly with the types of enrichment commonly applied on commercial farms. More detailed observations of how pigs interact with different enrichments, other pigs, and their environment would improve our understanding of how to combine enrichments to minimize tail biting. This is essential because although single non-straw enrichments can reduce tail biting significantly, the remaining levels of damage can still be high.

Abstract

Tail biting remains a common problem in pig production. As producers are reluctant to use straw to reduce this behaviour, we review studies on the effectiveness of other types of enrichment. Roughage, hessian sacks, compost, fresh wood, space dividers, rope, and providing new objects regularly can significantly reduce tail damage. These results should be interpreted with some caution, as often only one study per enrichment could be identified. No evidence was found that commonly applied enrichment objects (processed wood, plastic or metal) reduce tail biting significantly unless exchanged regularly, even though multiple studies per type of enrichment were identified. Many studies evaluated the duration of enrichment use, but few evaluated the manner of use. This hampers identification of combinations of enrichment that will satisfy the pig’s motivation to eat/smell, bite, root and change enrichments, which is suggested to reduce tail biting. New objects designed to satisfy specific motivations were shown to receive high levels of interaction, but their effectiveness at reducing tail damage remains unknown. More in-depth study of how pigs interact with non-straw enrichment, which motivations this satisfies and how this affects behaviour towards conspecifics, is necessary to optimize enrichment strategies. Optimization is necessary because ceasing tail docking in a way that improves pig welfare requires more effective enrichments than those described in this review, or alternatively, better control over other factors influencing tail biting.

Effects of wet/dry feeder and pen stocking density on grow-finish pig performance

Three thousand one hundred and eighty-two terminal cross pigs (barrows and gilts) PIC line 359 sires × 1,050 dams were used from three consecutive grow-finish groups (initial BW of 21.51 ± 0.42 kg, 31.61 ± 1.18 kg, 29.41 ± 0.28 kg for replicates 1-3). Pigs were randomly assigned to each pen at the start of the trial and the research period continued for 106, 94, and 100 d for the first, second, and third replicates, respectively. The experimental treatments were designed as a two by three factorial (pen space of 0.65 or 0.78 m²/pig with 10, 13, or 16 pigs per feeder space), each pen had an equal number of barrows and gilts with 20, 26, and 32 pigs per pen for the 10, 13, and 16 pigs per feeder space pens. Each pen was equipped with one double-sided wet/dry feeder, 37.5 cm wide, with one nipple drinker. All pigs had ad libitum access to feed and water supply during the trial period. Pigs for all the three replicates were fed with the same series of diets. Pigs were weighed by pen at the start of trial and at the end of the trial to calculate ADG. Feed was removed from the feeders and weighed to determine ADFI and G:F. To express floor space allowance, the k value was estimated by the equation: space per pig   ( m 2 ) = k × BW  ( kg ) 0.67 . No interactions (P > 0.05) of floor space allowance with pigs per feeder were observed. Pigs with less floor space allowance had reduced BW (128.8 vs. 129.5 kg, P = 0.026), ADG (1.00 vs. 1.02 kg/d, P = 0.002), and ADFI (2.52 vs. 2.61 kg/d, P < 0.001). However, G:F was improved (0.402 vs. 0.397, P = 0.039) with less floor space allowance per pig. Increased pigs per feeder space reduced final BW (129.7, 129.4, 128.4 kg, linear; P = 0.001). However, ADG had a quadratic relationship (P = 0.005) with pigs per feeder space with means of 1.03, 1.01, and 1.01 kg/d for 10, 13, and 16 pigs per feeder space. Overall, ADFI had a quadratic relationship (P < 0.0001) with number of pigs per feeder space with means of 2.62, 2.52, and 2.55 kg/d for 10, 13, and 16 pigs per feeder space. Gain efficiency had a quadratic relationship (P = 0.005) with number of pigs per feeder space with means of 0.395, 0.404, and 0.400 for 10, 13, and 16 pigs per feeder space. In conclusion, a floor space allowance of 0.65 m²/pig in the grow-finish period reduced ADFI and ADG compared with 0.78 m²/pig. Overall, with the type of wet/dry feeder used in this study, 10 pigs per feeder had the greatest ADG and ADFI, compared with 13 or 16 pigs per feeder space. However, G:F improved as the number of pigs per feeder space increased.