changing to pig housing systems which provide more comfort & ease of movement
can cause initial health & fertility problems
arthritis outbreaks in finishers
110 kg gilt: typical stance suggestive of joint pain, reluctance to walk, no gross joint enlargement. M.hyosynoviae arthritis of both elbow & both stifle joints (courtesy of Dr. Bill Smith)
Dr. Bill Smith of the Scottish Agricultural College Veterinary Science Division reported two outbreaks of arthritis in finisher pigs on deep straw housing systems:
A finishing unit housing finishers on deep-straw experienced a rise in abattoir condemnations for arthritis. However, a second farm, using weaners (nursery pigs) purchased from the first but using using fully-slatted housing, showed no increase.
Table F1: arthritis in two finishing units with differing floors
straw bedded house fully slatted house Management 195 pigs of approx. 30 kg delivered weekly into empty deep straw yard
280 pigs of approx. 30 kg delivered weekly into slatted floor pens (15 pigs per pen)
190 pigs sent to abattoir
83 (43.7%) had arthritis
(1 totally condemned 82 partially condemned, total meat rejected = 834 kg
178 pigs sent to abattoir
5 (2.8%) had arthritis
data from Smith, W.J. (1999) Veterinary Record, 145, 440
Weaners were allocated randomly to the two finishing units at around 30 kg liveweight. Both groups of finishers were fed the same diet and ration.
To control a mild swine dysentery problem, 2.5 kg/tonne of lincomycin was added to the feed of the straw-based pigs. The condemnation rate for arthritis fell to 2.9% over the next two weeks. However, condemnations rose again 3 weeks after lincomycin was withdrawn and salinomycin-sodium substituted (as a growth enhancer). Reintroduction of lincomycin was followed by another fall in condemnations for arthritis.
Farmer reported a condemnation rate of 18.5% for arthritis over a six week period for arthritis. The pigs were home bred and raised in a group of 500 (from 26-34 starting liveweight) on deep straw. These were all male pigs. The weaner gilts were reared in groups of 15 or 20 in totally slatted pens on an identical diet. The gilts had a condemnation rate of only 4.3% for arthritis.
More pigs in the deep straw yard required treatment (injections of lincomycin) for clinical signs of arthritis than in the slatted pens.
Mycoplasma hyosynoviae was grown from the joints of three of five condemned pigs on this farm. All five condemned pigs had histological lesions typical of M. hyosynoviae.
click on photo for detailed image & description
Dr. Smith concluded that supposedly higher welfare housing systems were apparently resulting in increased incidence of joint infections. The straw courts on both farms were managed on an "all-in, all-out" basis. Individual pens in the slatted houses were managed on an "all-in, all-out" basis, but the houses themselves were continuously occupied. Dr. Smith speculates that the triggering factor for arthritis may have been the large group sizes kept on straw. M. hyosynoviae can be carried on the tonsils and spread by nose contact. The number of possible disease transmissions increases exponentially with the number of pigs according to the formula:
number of transmissions = n2-n (where n = no. of animals)
e.g. if there are 4 pigs, there are 12 opportunities for disease transmission, but for 100 pigs there are (theoretically) 9,900 possibilities.
infectious disease outbreaks in sows
by Frank Tobin
specialist pig veterinarian with Holmefield Veterinary Group Yorkshire U.K.
Although it is less than a year since all pig farmers in the United Kingdom had to comply with the ban on stall and tether systems and adopt more "welfare friendly" loose-housing systems for sows, it is already plainly apparent that these new conditions impose considerably greater health management requirements for the sow herd.
One would have supposed that providing straw as bedding and allowing sows greater exercise would provide significant welfare benefits for dry sows. However, the extra activity and greater movement on concrete areas, together with an increase in bullying, has led to a marked increase in lameness among sows.
We have noticed a particular problem of lameness occurring in the weaning to service period. Bullying by dominant individuals, especially close to the feeders, has been very apparent. These extra interactions within the group tends to bring more sows into oestrus, which leads to riding by other sows. This contributes to the leg problems, which can multiply when sows are chased by dominant individuals and then slip on wet, dung-covered concrete.
Although the increase in leg problems has been seen in all types of loose-housed dry sow system, it has been most noticeable on units that did not comply with the new housing regulations until close to the deadline of January 1st 1999. This may simply be due to the fact that units which converted earlier have now settled down and the problem is now not so prevalent. However, it might be that, as vets, we have seen the problem before and are alerted to look out for it in these late-complying herds.
The switch from stalls to loose-housing systems for 'dry' sows has also resulted in a number of other conditions becoming more apparent. Of these, coccidiosis is possibly the most insidious - and affects virtually all herds.
With sows being housed in strawed accommodation, there is now almost constant re-infection of the herd as the sows forage through the bedding. During the summer months there is usually a marked increase in the condition, commonly seen as a scouring among suckling piglets from ten days of age. Having been infected themselves by oocysts shed in the sow's faeces, the piglets tend to show a loss of thrift, their growth rates stall and they become hairy and lose condition. This means they take longer to reach a satisfactory weaning weight but few losses tend to occur.
Treating the piglets with an anticoccidial drug does usually prove successful but the sow will always be present to re-infect her litter by shedding oocysts. These are difficult to kill and can build up in the farrowing pens. However, thorough cleaning and disinfection with OO-Cide has been shown to reduce the levels of oocyst contamination within the environment. Including an anticoccidial in the sow's diet prior to and after farrowing may help to reduce the burden she carries, but as soon as she returns to the loose-housed system, she will quickly become infected again.
Few farmers are likely to clean out straw-based pens for their sows between batches. In fact, with dynamic systems this is impossible to do. Consequently, worm infestations are likely to become a feature of the herd and problems are already beginning to appear.
The major benefit of slatted flooring in stalls was the removal of faecal material away from the sow to prevent worm eggs being ingested. However, with strawed systems, the worm eggs remain in close proximity to the sows and are easily picked up as they root through their bedding. Therefore, even worm-free sows entering the groups will soon become infested with worms and even with regular, routine worming, the problem will quickly return as the sows become re-infected.
Routine worming of sows before they enter the farrowing quarters is advised to prevent the subsequently litters picking up a substantial worm burden shortly after birth. However, it is likely that piglets will become infected reasonably early in life and worming programmes may now need modification so that these infestations can be tackled earlier in the growing period otherwise feed conversion efficiency and growth rates may be adversely affected.
Lice & Mange
Routine treatment with ivermectin will also be necessary in most herds to counter mange and lice in strawed housing. If mange occurs in only a few sows, this could soon spread through the herd as the housing conditions are highly suited to the transfer of the mites and lice from sow to sow.
Though the mites do have a relatively short life cycle, it is important to treat mange with a long acting and persistent product like ivermectin so that larvae and hatching eggs are cleared along with the adults during each treatment.
The wet harvest in 1998 was followed by a rainy winter and spring has had a devastating impact on the quality of straw this year, especially that stored outside. Mould growth on the straw is a particular problem for those producers having to purchase bedding for their sows. High levels of mycotoxins will have developed within the straw and if this is eaten by the sows, various forms of mycotoxicosis may occur that can impact on performances, especially breeding results.
Another disease that is difficult to control in straw yards is swine dysentery but all enteric diseases can quickly spread in such housing. Sows tend to harbour swine dysentery and then pass this on to their progeny in the farrowing house. If the disease is a problem within the herd, it may be necessary to implement a regular, routine treatment programme to control the disease in the growing/finishing section.
Body condition & Bullying
The legislation to ban stall and tether systems was brought in by the British government to improve sow welfare, allow the sow to obtain regular exercise and to allow them to exhibit natural behaviour patterns. However, not all the straw-based alternative housing systems that have been adopted to accommodate the dry sows have made management of the sow herd as easy as it ought to be.
The feeding system used in straw yards can influence the condition of the sows more than seemed to occur in stalls. There is now much greater variation in body condition within the sow herd, due either to under or over feeding.
Some of this may be because stockmen are not identifying the problem sows and removing them from their groups to allow them to receive specific treatment. However, it is more likely to be due to dominant sows bullying others in the group to obtain extra feed, especially if this is fed on the floor. Stockpersons should be able to exert the right control over sow condition. But this can be difficult with floor feeding systems unless either the dominant sows are removed or any that suffer due to bullying can be given special attention away from the group.
Over-feeding is likely to be much more of a long-term problem in herds than having a handful of sows that fail to gain the desired level of condition during the dry period. The modern hybrid sow still has the capacity to continue growing well into her breeding life and this means that excess food consumption is translated into rising body size during pregnancy.
If this fault in feed intake is not prevented, there is the danger that some sows will become too big to fit into the farrowing crates, with all the attendant management problems that this will entail. Sows that also eat too much during pregnancy may also cause problems during the farrowing process, they may be more susceptible to mastitis during the subsequent lactation, they can become clumsy and more likely to overlay their piglets and they are also likely to have a depressed appetite while they are suckling their progeny so that milk flow is inadequate.
If one thinks back to the adoption of the sow stall, this occurred because many outdoor units that fed their sows in a line on the ground had major problems with vulva biting. The move indoors into stalls gave the pregnant sow the protection from bullying not possible in an extensive system and bitten vulvas became a thing of the past. Present day outdoor herds do not seem to have problems with vulva biting.
The way we now feed and manage groups of sows in yards is influencing an increase in the incidence of vulva damage being seen again on units. This is seen most often in dynamic groups, especially among the heaviest in-pig females where the vulva has begun to swell in preparation for farrowing.
However, it can also occur in small, stable groups where the feed is dumped onto the floor in a confined area, leading to bullying and biting by the dominant sows to obtain more than their share of the food. Small groups fed by trickle or liquid feeding systems appear to suffer from this problem less frequently.
Vulva biting can be a costly problem to the producer since scar tissue on vulvas that have healed can lead to further difficulties during parturition. The birth canal can become restricted at the exit, making it difficult for the piglets to pass through. This either results in sows not being able to farrow or in the vulval tissue tearing as the piglet is forced through. Sows that are damaged in this way may need veterinary attention to stitch up the tear but ultimately their breeding lives can be greatly shortened by the damage.
Keeping sows in loose-housed systems has satisfied the welfare lobby but the job of managing the pregnant animal is probably more difficult now than when sows were housed in stalls. In terms of the health of the breeding herd, it is questionable whether the move to loose housing has actually improved the overall welfare of the sow. There are now so many more diseases and conditions affecting sows that were easily excluded in stalls. Perhaps, over the next five years the most suitable dry sow system will be found to satisfy everyone!
A Pig Farmer's Experience
by Sue Smith
Pig producer, North Yorkshire, U.K.
Since the ban on housing sows in individual stalls, I keep my sows in a dynamic group, of about 60 sows. Every week 4-6 are added and 4-6 taken out to farrow.
We have seen problems with vulva biting and a drop in conception rates (due to excess stress at mixing and failure to implant, or resorbtion of the embryos).
I am not happy with the fact that there is no break in the disease cycle, and even though we clean out every 4-6 weeks, & completely rebed & put 'Stalosan' (disinfectant) down, the mites, & mange bugs & other nasty things are still lurking in the pen.
I am about to split the sows down into smaller stable groups of 8-10, and I'm sure this will improve herd health, & management.
Infertility Problems in Finland
by Dr. Olli Peltoniemi
I am a consultant to some newly-established loosely housed dry sow units and frequently see more repeat breeders, especially in late summer/early autumn on farms where sows are loose-housed immediately after mating. In my opinion, more skill is required from farmers to maintain similar fertility level in loose housing as compared to the former individual housing. Skill and experience is something that you can only gain with time, therefore I doubt if we will see great improvements in this problem 'overnight'.
See our published data on this problem: Peltoniemi, O.A.T. et al., 1999. "Seasonal and management effects on fertility of the sow: a descriptive study". Animal Reproduction Science, 55, 47-61
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