Effect of pen design on tail biting and tail-directed behaviour of finishing pigs with intact tails.

Tail biting is a welfare and economical concern in modern pig production. One common preventive measure used throughout the world is tail docking, which is generally considered one of the most effective methods for limiting tail biting. However, tail docking is a painful mutilation and systematic tail docking is not allowed in the EU. Therefore, the aim was to compare pig behaviour and the prevalence of tail biting in finishing pigs with intact tails housed in two different pen designs under Danish commercial conditions. PEN1 was a traditional Danish pen and PEN2 was inspired by Swedish finisher pen design and had a larger proportion of solid floor area (PEN1: 1/3 and PEN2: 2/3), reduced group size (PEN1: 15 and PEN2: 12), increased space allowance per head (PEN1: 0.7 m2 and PEN2: 0.89 m2) and straw allocated on the floor (PEN2) whereas straw was provided in a straw rack in PEN1. Tail damage observations were carried out daily by the stockperson and every 2 weeks one trained research technician assessed tail damages according to a tail scoring system. Tail lesions were observed in 51% of PEN1 and in 11% of PEN2 (P < 0.001). PEN1 had higher prevalence of tail damages than PEN2 (23% v. 5%, P < 0.001). Behavioural observations were carried out by the use of video recordings. Pigs in PEN2 tended to spend more time on tail-directed behaviour than pigs in PEN1 (P = 0.07), whereas pigs in PEN1 tended to spend more time on ear-directed behaviour (P = 0.08). Pigs in PEN2 spent more time on straw-directed behaviour compared to pigs in PEN1 (P < 0.001). Pen design did not affect time spent on other penmate-directed behaviour. In addition, the level of welfare between the two pen designs was compared using the Welfare Quality® protocol. PEN2 received an overall score of 'excellent' while PEN1 scored 'enhanced'. PEN2 scored higher on all principles besides 'good health', where PEN1 scored better on lameness and wounds. The main measurements accounting for the differences were water supply, huddling, tail biting, social behaviour and fear of humans. In conclusion, the combination of increased space allowance, increased area of solid flooring, straw allocated onto the floor and reduced group size (PEN2) resulted in fewer tail damaged pigs and a better overall welfare assessment, despite a tendency for more tail-directed behaviour.

Temporary confinement of loose-housed hyperprolific sows reduces piglet mortality.

The objective of this study was to investigate piglet mortality in a commercial setting where sows were accommodated in a loose-housed system with an option to confine the sow for a few days around farrowing and during early lactation. The study was conducted in a Danish piggery where records were obtained from 2,139 farrowings. Sows were randomly allocated to 1 of 3 treatments: loose-loose (LL), loose-confined (LC), and confined-confined (CC). In LL, sows were loose housed from the time they entered the farrowing pens to weaning. In LC, sows were loose housed until farrowing was finished and then confined to d 4 after farrowing. In CC, sows were confined at d 114 of gestation to d 4 after farrowing. All sows were loose housed from d 5 to weaning. Total piglet mortality was analyzed at batch level to include piglets fostered by nurse sows and at sow level to analyze the effects of confinement during different time periods. Total piglet mortality was greater in LL (26.0%) and LC (25.4%) compared with CC (22.1%; < 0.001). The proportion of stillborn piglets was not different between treatments ( = 0.21) but a larger proportion was crushed in LL (10.7%) compared with LC (9.7%; = 0.03), which again was greater than CC (7.8%; < 0.001). Piglet mortality before equalization was lower in CC (3.7%) than in LL (7.5%) and LC (7.0%; < 0.001). Confinement reduced mortality from litter equalization to d 4 (7.6% for LL vs. 6.7% for LC; = 0.01) but more so in CC (5.6%) than in LC ( < 0.001). From d 4 to weaning, LL had lower mortality (5.6%) than LC (6.9%) and CC (6.6%; = 0.01). A larger proportion of sows in CC were classified as "low mortality" compared with LL and LC both before ( < 0.001) and after ( = 0.002) litter equalization. The results in this study emphasize that the period of time from the birth of the first piglet to litter equalization is important in relation to piglet mortality. The results also suggest that confinement for 4 d after farrowing can reduce mortality in this specific period, but only confinement from d 114 of gestation to d 4 after farrowing reduced total piglet mortality.

The effect of long or chopped straw on pig behaviour.

In the EU, pigs must have permanent access to manipulable materials such as straw, rope, wood, etc. Long straw can fulfil this function, but can increase labour requirements for cleaning pens, and result in problems with blocked slatted floors and slurry systems. Chopped straw might be more practical, but what is the effect on pigs' behaviour of using chopped straw instead of long straw? Commercial pigs in 1/3 slatted, 2/3 solid pens of 15 pigs were provided with either 100 g/pig per day of long straw (20 pens) or of chopped straw (19 pens). Behavioural observations were made of three focal pigs per pen (one from each of small, medium and large weight tertiles) for one full day between 0600 and 2300 h at each of ~40 and ~80 kg. The time spent rooting/investigating overall (709 s/pig per hour at 40 kg to 533 s/pig per hour at 80 kg), or directed to the straw/solid floor (497 s/pig per hour at 40 kg to 343 s/pig per hour at 80 kg), was not affected by straw length but reduced with age. Time spent investigating other pigs (83 s/pig per hour at 40 kg), the slatted floor (57 s/pig per hour) or pen fixtures (21 s/pig per hour) was not affected by age or straw length. Aggressive behaviour was infrequent, but lasted about twice as long in pens with chopped straw (2.3 s/pig per hour at 40 kg) compared with pens with long straw (1.0 s/pig per hour at 40 kg, P=0.060). There were no significant effects of straw length on tail or ear lesions, but shoulders were significantly more likely to have minor scratches with chopped straw (P=0.031), which may reflect the higher levels of aggression. Smaller pigs showed more rooting/investigatory behaviour, and in particular directed towards the straw/solid floor and the slatted floor than their larger pen-mates. Females exhibited more straw and pen fixture-directed behaviour than males. There were no effects of pig size or sex on behaviour directed towards other pigs. In summary, pigs spent similar amounts of time interacting with straw/solid floor when long and chopped straw were provided, and most aspects of pig-directed behaviour and injuries were not affected by straw length. There was an increase in pigs with minor shoulder lesions with chopped straw, perhaps because of increased aggression. The use of chopped straw as an enrichment material for pigs warrants further investigation in larger and more detailed studies.

Behaviour of liquid-fed growing pigs provided with straw in various amounts and frequencies.

Straw possesses many characteristics that make it attractive to pigs and can therefore be effective in preventing negative penmate-directed behaviours. However, straw is difficult to handle in current vacuum slurry systems under most commercial conditions and can therefore only be used in limited amounts. To occupy pigs effectively, straw must remain attractive to pigs throughout the whole day; hence, have a certain degree of novelty. We investigated the penmate-directed behaviour of liquid-fed growing pigs in a production herd, assigned to five experimental treatments: 1×25, 1×50, 1×100, 2×50 and 4×25 g of chopped straw/pig per day, with 20 replicates of each treatment (pen was regarded as experimental unit). Behaviour was observed at two different growth stages; ~40 and 80 kg live weight of the pigs. Activity and exploratory behaviour directed at penmates, straw, pen components and the slatted floor were registered continuously for 15 min of each hour during day time (0600 to 2200 h) by use of video observation of three focal pigs per pen. The pigs were active for about one-third of the day corresponding to ~5 h/day. Of the active time, an average of 7% (35 min) was spent on penmate-directed behaviour. The pigs were more active and increased their straw-directed behaviour when provided with 100 g straw/pig per day compared with 25 and 50 g (P<0.001). However, penmate-directed behaviour was not reduced with an increased amount of straw (P>0.05), and there was no effect on pigs' behaviour when straw provision was increased per day (P>0.05). Pigs became less active and reduced their straw-directed activities when their weight increased from 40 to 80 kg live weight (P<0.001), but the amount of penmate-directed behaviour was similar (P>0.05). Further, the residual straw results indicated that perhaps a more frequent straw provision could help establish a more even level of fresh available straw during the day. However, the frequent straw provision did not occupy pigs more than one daily allocation did. In conclusion, there was no difference in penmate-directed behaviour of the pigs when given 25 or 50 g of straw/pig per day compared with 100 g of straw/pig per day, nor were there any difference when 100 g of straw/pig per day was provided more frequently.

Higher preweaning mortality in free farrowing pens compared with farrowing crates in three commercial pig farms.

If loose-housed farrowing systems are to be an alternative to traditional farrowing crates, it is important that they can deliver the same production results as can be achieved in farrowing crates under commercial conditions. The aim of this study was to compare preweaning mortality in farrowing crates and free farrowing pens (FF-pens) within herds that had both systems. The study was conducted over 2 years in three commercial Danish herds that had FF-pens as well as traditional farrowing crates in their farrowing unit. Piglet mortality was analysed in two periods: before litter equalisation and after litter equalisation. Linear models were used to analyse effects of housing (crate or pen), herd (Herd A, B or C), parity (parities 1, 2, 3 to 4 or 5 to 8) as well as the effect of number of total born piglets on mortality before litter equalisation, and the effect of equalised litter size on piglet mortality after litter equalisation. All corresponding interactions were included in the models. Before litter equalisation piglet mortality was higher (P<0.001) in pens (13.7%) than in crates (11.8%). Similarly, piglet mortality after litter equalisation was higher in pens than in crates in all three herds, but the difference between pens and crates were dissimilar (P<0.05) in the different herds. In addition, piglet mortality, both before (P<0.001) and after litter equalisation (P<0.001), grew with increasing parity of the sows. Mortality before litter equalisation moreover increased with increasing number of total born piglets per litter (P<0.001), and mortality after equalisation increased when equalised litter size increased (P<0.001). No significant interactions were detected between housing and parity or housing and litter size for any of the analysed variables. In conclusion, there is knowledge how to design pens for free farrowing; but this study showed a higher preweaning mortality in the FF-pen. Nonetheless a noteworthy proportion of the sows in the FF-pens delivered results comparable to those farrowing in crates. This indicates that FF-pens are not yet a robust type of housing for farrowing sows.

Individual physical characteristics of neonatal piglets affect preweaning survival of piglets born in a noncrated system.

The aim of this study was to investigate the effects of individual physical characteristics on preweaning survival and growth of piglets born in a noncrate system. Data were collected from 3,402 neonatal piglets from 203 Landrace × Yorkshire sows housed in noncrate pens in a commercial Danish sow herd. Piglets were categorized into groups according to their survivability: surviving to weaning (SURV), stillborn (STILL), or dead between birth and weaning (DBW), which was subdivided into dead d 0 to 1 after farrowing (DEAD1) or dead d 2 to 26 after farrowing (DEAD26). Linear models were used to determine which physical characteristics affected survivability and growth of piglets. Results showed that characteristics related to the individual piglets had a greater degree of explanatory power in relation to survival than variables related to the sow. Survival of piglets increased if piglets were females (P < 0.001), had a greater body mass index (P < 0.001), and were born to sows of parity 3 or more (P = 0.017). Piglets with a greater birth weight were more likely to survive (P < 0.001), but birth weight was inferior to body mass index in explaining differences between SURV and DBW. Piglets that died 2 to 26 d after birth had a lower birth weight (P < 0.001), were born to sows of parity 1 or 2 (P = 0.014), and were born after a shorter gestation (P = 0.011) compared with SURV. Piglets that died on d 0 to 1 after birth had a lower body mass index (P < 0.001), displayed a greater degree of growth restriction (P = 0.004), and were born in large litters (P = 0.005). The gender of the piglets affected survivability at both d 0 to 1 (P < 0.001) and d 2 to 26 (P < 0.001). Piglets in DEAD1 differed from STILL by having a shorter crown to rump length (P < 0.001), a birth weight that deviated more from the mean weight of the litter (P = 0.001), and being more likely to be born before d 116 of gestation (P = 0.008). The only physical characteristic that was important for growth performance in the suckling period was birth weight (P < 0.001), yet using only birth weight as an indicator for survivability was too simplistic. The results of this study emphasize that individual characteristics of neonatal piglets could serve as indicators of survivability of piglets born in noncrate systems; however, the results suggest that the importance of characteristics differed in different periods of the preweaning period.

Sperm chromatin structure integrity in liquid stored boar semen and its relationships with field fertility.

Extended semen doses from some boars used for AI have been shown to develop high levels of sperm DNA fragmentation during storage. Studies in other animals and humans have shown that if DNA damage is present in a certain percentage of the sperm cells the fertility potential of the semen sample is reduced. The objectives of the present study was to determine the relationship between sperm DNA fragmentation measured using the sperm chromatin structure assay (SCSA) in extended stored semen and field fertility in the boar. Three ejaculates from each of 145 boars were collected. Preparation of the semen doses included dilution with an EDTA extender and storage for up to 72 h post collection. The semen doses were assessed using flow cytometric methods for the percentage of viable sperm (PI/SYBR-14) and sperm DNA fragmentation (SCSA) at 0, 24, 48, and 72 h. A total of 3276 experimental inseminations in Danish breeding herds were conducted. The results showed that for 11 (7.6%) of the boars at least one of the three samples showed a value of DNA fragmentation index (DFI) above 20% within the storage period. Total number of piglets born (litter size) for Hampshire, Landrace and Danish Large White boars was, respectively, 0.5, 0.7 and 0.9 piglets smaller per litter when DFI values were above 2.1% as opposed to below this value. In conclusion the SCSA technique appears to be able to identify individuals with lower fertility with respect to litter size, and could in the future be implemented by the pig industry after a cost-benefit analysis.