The effects of straw in crated farrowing systems on peripartal behaviour of sows and piglets

Br. vet.

_7. (1988) . 144, 139

THE EFFECTS OF STRAW IN CRATED FARROWING SYSTEMS ON PERIPARTAL BEHAVIOUR OF SOWS AND PIGLETS S. A . EDWARDS* and S. J . FURNISSt ADAS, Terington Experimental Husbandry Farm, Temngton St Clement, Kings Lynn, Norfolk, PE34 4PW

SUMMARY A continuous video recording of the behaviour of sows and their piglets was made from before farrowing until 48 h after the birth of the last piglet . Ten litters, receiving chopped straw bedding daily, were compared with 10 litters in unbedded farrowing crates under similar housing and management conditions . Provision of straw had no significant effect on farrowing duration, which was very variable, or on piglet survival and growth rate . Sows made more major posture changes (transitions between standing, sitting and lying) in the early stages of farrowing (median 4, 2, 0 for inter-birth intervals 1, 2 and 3+ respectively) . This tended to be more marked in the absence of straw bedding (19 . 5 versus 5 major movements in the first three inter-birth intervals, P=0 . 07, and 4 . 5 versus 2 transitions between sternal and lateral recumbency, P=0-07) . Early born piglets took longer to find the udder (45, 21, 11 min for piglets 1, 2 and 3 respectively) with no significant effect of straw provision . The inter-birth interval increased towards the end of farrowing and more stillbirths occurred . In the 48 h after farrowing sows without straw made more major posture changes (2 . 0 versus 1 . 4/h, P =0 . 05) and also tended to make more transitions between sternal and lateral recumbency (0 . 8 versus 0 . 6/h, P=0-06) . Piglets without straw spent more time in the heated forward creep box (29 versus 4%, P<0 . 01) . There was no significant effect of straw on the time piglets spent on the udder (39 versus 44%), the frequency of cyclical suckling (1 . 3 versus 1 . 5/h) or the time spent active (42 versus 45%) .

INTRODUCTION The newborn piglet is very vulnerable on account of its small size, limited body reserves and poor immunity status . Numerous surveys have shown that up to 30% of all piglets alive at the onset of parturition do not survive until weaning (reviewed by English & Wilkinson, 1982) . The majority of these deaths occur within 48 h of farrowing and are attributed to crushing and starvation, which are interconnected with piglet vigour and * Present address The North of Scotland College of Agriculture, 581 King Street, Aberdeen, AB9 IUD . t Present address : ADAS, Bridgets E .H.F., Martyr Worthy, Winchester, Hants, S021 IAP .



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environmental temperature (English & Wilkinson, 1982 ; Edwards, Malkin & Spechter, 1986). The farrowing environment is thus an important factor affecting piglet survival . This is reflected in the widespread use of farrowing crates to minimize crushing of piglets and heated creep areas to provide a thermally suitable area away from the sow for the piglets . Current UK welfare codes (MAFF, 1983) strongly recommend the provision of straw or a similar bedding material, emphasizing its thermal, physical and recreational properties . However, to reduce labour requirements many farms have dispensed with bedding for the farrowing sow, using an insulated concrete floor or one which is partly or wholly perforated to facilitate self-cleaning (Baxter, 1981) . The absence of bedding might have adverse effects on piglet survival by increasing sow restlessness and thus prolonging farrowing, hindering suckling and giving rise to more opportunities for crushing of piglets . Various comparisons of performance in farrowing systems with and without straw have been made, with conflicting results as discussed by Edwards, Lightfoot & Spechter (1987) . Such comparisons have usually confounded floor type and provision of bedding . This study investigated behavioural parameters of sows and newborn piglets which might affect neonatal survival and examined the effects of provision of straw bedding in otherwise identical conditions of housing and management . The aim was to assess the value of providing straw for farrowing sows under current intensive housing conditions .

MATERIALS AND METHODS Animals and management Multiparous LandraceXLarge White sows, which had previously been housed in groups of three animals in free-access stalls, were moved into the farrowing house 1 week before their expected farrowing date . The farrowing accommodation comprised a room containing 12 pens with the room temperature controlled at 20 °C by Automatically Controlled Natural Ventilation (Spackman et al., 1983) . Each farrowing pen was 2 . 4X1 . 5 m with a centrally positioned farrowing crate 1 m and an insulated creep box 0 . 6X1 . 5 m placed in front of the crate . This box contained a thermostatically controlled, dull emitter heater, set for 30°C, and a 15 watt attraction light . Entrance was by two popholes 25X30 cm, one situated on either side of the crate . The floor of the pen was of insulated concrete with a small punched metal grid, 20X50 cm, in the centre rear of the pen for drainage . The sows were fed twice daily on a pelleted commercial diet and had water freely available from a drinker situated in the trough . Faeces and soiled bedding were removed each morning from the rear of the pen . When farrowing appeared imminent a 250 watt radiant heater was suspended 40 cm above the floor on one side of the crate, 70 cm from the rear of the pen . This was removed on the morning after farrowing and the newborn piglets were shut in the creep box for weighing and teeth clipping . Piglets were weighed again at weaning which took place at 3 weeks of age . Experimental recording The study involved 10 sows farrowing in pens with no bedding and 10 sows given chopped straw bedding at the rate of approximately 5 kg per pen initially, and then 700 g

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each day after removal of soiled material . A low light level camera and time lapse video recorder were used to make continuous recordings of behaviour from before farrowing commenced until 48 h after the birth of the last piglet . From these were obtained the time of each birth, the posture of the sow, the time taken by each piglet to locate the udder and the number of posture changes by the sow between births . These were subdivided into transitions between standing, sitting and lying, called major posture changes, and transitions between sternal and lateral recumbency, called minor posture changes . In the post-farrowing period the posture of the sow, the activity and location of the piglets, and the total number of major and minor posture changes were recorded at 20-min intervals . Detailed information on any piglet deaths which occurred was collected and is reported elsewhere (Edwards et al., 1986) . Behavioural parameters were compared using non-parametric statistics . It was hypothesized that absence of straw bedding would result in an increased frequency of posture changes by the sow, prolonging parturition and increasing the probability of piglets having delayed suckling and being crushed .

RESULTS Performance results from the litters involved in the study are shown in Table I . There were no differences between the treatments in any performance parameters . Table I Performance of litters with and without straw bedding

No . of litters No . born alive No . born dead No . weaned at 21 days Piglet weight at weaning (kg) Values are means with

SEM

Chopped straw bedding

No bedding

10 11-4(0-83) 0-7(0-22) 10-0(0-47) 5-6(0-46)

10 11-6(0-62) 1-0(0-33) 10-2(0-63) 5-8(0-26)

in parentheses .

Farrowing behaviour The duration of farrowing showed great individual variation with no indication of a treatment effect . Median durations were 313 min (range 79-689) for sows with bedding and 200 min (range 93-681) for those with no bedding . The inter-birth interval for individual piglets varied from 0 to 545 min, with the piglet born alive and vigorous in the latter, extreme case . The median interval between birth, . was 30 min (range 6-62) for sows with bedding and 19 min (range 8-47) for those without . Sows without bedding tended to make more posture changes during farrowing (5 . 2 versus 2 . 3 major posture changes per hour, P<0 . 10 ; 2 . 7 versus 1 . 1 minor posture changes per hour, P<0 . 10) . Changes occurred in the behaviour of the sows and piglets as farrowing progressed . Sows made more major posture changes in the early stages of farrowing (medians of 4, 2 and 0 for birth intervals 1, 2 and 3 respectively, P<0 . 05) and early born piglets took



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longer to find the udder (45, 21 and 11 minutes for piglets 1, 2 and 3 respectively, P<0 . 05) . Table II shows the effects of straw bedding on behaviour at subsequent stages of farrowing . Sows made more posture changes between the first three births than between subsequent births and this tended to be more marked in the absence of bedding . The interval between these births was greater but was not affected by treatment . Initial sow restlessness made it more difficult for piglets to locate the udder and the first three piglets took signficantly longer than mid-farrowing piglets . The interval between births increased again for the later born piglets, although the sow was not any more restless, and the incidence of stillbirths increased . However, if these later piglets were born alive they took no longer to locate the udder and did not have a higher probability of failing to suckle . Later born piglets took longer to locate the udder in litters without bedding . Table II The effect of provision of bedding on sow and piglet behaviour in relation to the period of farrowing Piglet or interval no . First 3 Middle group Last 3 SB NSB SB NSB SB ASB

Significance of time effects

Sow behaviour

Interval between births (min) changes per interval : major minor Piglets born dead

22

21

11

10

18

24

First versus mid P<0-05 Mid versus last P<0-01

0-3 0-3 7

0 0 10

0-7 0-2 13

First versus mid P<0 . 01 First versus mid P<0 . 01

13 0

25 * 3

First versus mid P<0 . 01

No. of posture

1 . 7 6 . 5t 0 0-7 1 . 3t 0-4 8 0 0

Piglet behaviour

Time to locate udder (min) Failing to suckle

26 3

29 0

16 4

26 9

SB, chopped straw bedding ; NSB, no bedding ; tSB versus NSB, P<0 . 10 ; *SB versus NSB, P<0-05 . Once the sow had settled, delayed udder location was generally associated with piglets which were lethargic at birth or which initially went to the dorsal side of the sow . Sows without bedding farrowed more of their piglets while lying with their udder towards the supplementary heater (50 versus 27%, P<0-01) but this factor did not systematically affect the time which piglets took to locate the udder . Post farrowing behaviour

In the 48 h after farrowing sows spent most time in lateral recumbency, with the udder exposed for nursing (75 and 78% of time for sows without and with straw, Ns) . Sows without straw made more major posture changes (2 . 0 versus 1 . 4 per hour, P=0 . 05) and also tended to make more minor posture changes (0 . 8 versus 0 . 6 per hour, P-0 . 06) . Table III shows the effects of straw bedding on behaviour in relation to the time after farrowing . During farrowing and for 2-5 h thereafter piglets were very active in suckling



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PERIPARTAL BEHAVIOUR OF PIGS

Table III The effect of provision of straw bedding on the behaviour of sow and piglets in relation to time after farrowing

0-12 SB NSB

Time after farrowing (h) 12-24 24-36 SB NSB SB NSB

36-48 SB NSB

4 1 11 82

7 3 17 75

Significance of time effects

Sow behaviour

Time Standing Sitting Sternal recumbency Lateral recumbency No . of position changes per h : major minor "/o

3

0 7 89

1.1 0. 5

3 3 15 79

1.5 1.2

1 .6 0.7

3 0 19 71

1.7 0. 7

3 3 12 82

1 .2 0. 5

4 6 15 76

1.6 0. 5

1 .6 0. 5

4 4 19 72

2 .2* 0.6

Piglet behaviour "/" Time active

60

63

40

47

39

34

33

27*

P<0 . 01 for each period

% Time on udder

57

55

49

41

42

31

35

22*

P<0 . 01 for periods

7

9

4

0

1*

4 32*

4 16

2 68**

2, 3, 4

in crate in creep No .suckings/h

0

5 8**

4 3

1.6

1 .4

1 .4

1 .4

1 .2

Values presented are medians and will not necessarily sum to 100% . SB, chopped straw bedding ; NSB, no bedding ; *SB versus NSB, P<0 . 01 .

P<0 . 01 for each period

1 .2

P<0 . 05 ;

**SB versus NSB,

to obtain colostrum, and remained almost continually at the udder . As time progressed suckling bouts became more distinct, with the litter alternately suckling and resting at intervals of about 40-45 min . The frequency of this cyclical suckling was similar for piglets with and without bedding . The amount of time piglets spent active decreased with time after farrowing, as did the amount of time they spent on the udder . The proportion of time spent in the heated creep box was very low, especially in the case of litters with bedding (29 versus 4% of the 48-h period for litters without and with straw, P<0 . 01) . Use of the forward creep increased with time after farrowing but piglets with straw bedding showed a much greater tendency to remain near the udder or in the area either side of the crate . The time for which the supplementary heater remained on after farrowing was similar for both treatments (927 and 910 min for litters with and without bedding) . The proportion of time spent lying with the udder towards the heater in relation to total time in lateral recumbency was 45% for sows on straw and 54% for those without (P<0 . 10) . There was no apparent relationship between this orientation of the sow and the predominant location of her piglets . During the time that the supplementary heater was on there were no significant differences in the proportion of time spent by piglets without



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or with straw on the udder (45 versus 53%) or under the supplementary heater (30 versus 22%), but those without straw spent less time in the unheated areas outside the crate (10 versus 19%, P<0 . 05) .

DISCUSSION In traditional, unconfined farrowing systems straw plays a very important role as substrate for nest building by the sow . The nest provides both physical cushioning and thermal insulation for the newborn piglets, improving their chance of survival in a hostile environment . In modern farrowing systems, benefits in piglet survival and ease of management have resulted in the widespread use of farrowing crates and provision of improved thermal environments . Certain behaviours of the sow and piglets during and shortly after farrowing have a big effect on the incidence of piglet mortality . This study focused on these behaviours to determine whether, under modem farrowing conditions, any practical advantages could be demonstrated for the provision of straw . The duration of farrowing is of major importance for piglet survival . Piglets born after a long period of labour have a greater probability of being stillborn (Randall, 1972 ; English, Smith & MacLean, 1977) or of having reduced viability due to anoxia at birth (Randall, 1971) . Baxter & Petherick (1980) suggested that frustrating the nesting behaviour of sows might lead to a stress reaction which would delay and/or prolong farrowing . There was no evidence in the present study that the absence of straw, the substrate for nest building behaviour, resulted in prolongation of farrowing . A similar result was obtained by Svendsen, Bengtsson & Gustafsson (1984) in their comparison of straw bedded and slatted farrowing systems . However, it is likely that the spatial restriction imposed by the farrowing crate precluded normal nest building behaviour, even when straw was provided (Vestergaard & Hansen, 1984) and that this circumstance rendered the presence or absence of substrate irrelevant . The behaviour patterns utilizing straw have been shown to differ with housing circumstances in dry sows, with nest building behaviour being exhibited only in loose housing (Jensen, 1980) . The time taken by a newborn piglet to locate a teat and obtain colostrum is critical to its subsequent chances of survival (Bunger et al, 1984) . Colostrum provides both a high energy feed, at a time of critical energy balance, and a source of immunoglobulins (Spooner et al., 1978) . Although a piglet which does not feed retains the capacity to absorb colostral immunoglogulins for many hours, the concentration of immunoglobulin in the sow's colostrum is rapidly depleted as other piglets suckle from the teats . Udder location by the piglet depends on its vitality and the passivity of the sow . Although sows without straw tended to be more restless in the early stages of farrowing this did not significantly increase the time for udder location by their piglets . Later born piglets did take significantly longer to locate the udder in the absence of straw bedding . This is difficult to attribute to the behaviour of the sows, who showed very little movement . It is possible that the tendency for increased inter-birth intervals in these piglets resulted in decreased vitality (Randall, 1971) or that, in the absence of straw, birth fluids made the floor surface more slippery and impeded locomotion . The times recorded in this study were from birth to first udder contact since it was not always possible to see when ingestion of colostrum first occurred . It is likely that later born piglets took longer to suckle once at the udder (English et al, 1977) due to greater competition from littermates .



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The majority of piglet deaths are attributed to failure to achieve regular adequate nutrition and to crushing by the sow (English & Wilkinson, 1982) . There was no evidence that nutritional status was affected by the absence of bedding since the frequency of suckling and piglet liveweight gain were similar for both treatments . The probability of crushing will depend on the activity of the sow and the time spent by the piglets in her vicinity . Both during and after farrowing, sows tended to be more restless in the absence of bedding . This may be due to any one, or a combination, of several factors including the effect of bedding on physical comfort, by cushioning the concrete floor, and its thermal, nutritional and occupational effects . Fraser (1975) recorded increased time spent lying when dry sows were given straw, and demonstrated that this resulted from its ingestion . He failed to observe any effect on the frequency of position changes but, since this measure was based on 5-min time samples rather than observed posture changes which may be very transient, such effects cannot be ruled out . Ad libitum feeding of sows for several days before and after farrowing decreased the number of posture changes in the peripartal period (English, 1970), again suggesting the importance of gastrointestinal effects . The lower critical temperature of the newborn piglet is much greater than the optimum temperature for the sow and a heated creep area is commonly provided as a localized microenvironment for the piglets . In the absence of supplementary heat piglets may become chilled and lethargic or huddle close to the sow for warmth, increasing the probability of crushing when the sow moves . This study demonstrated the difficulty of attracting young piglets into a forward creep box, as previously shown in other studies of piglet behaviour during sample periods in the first few days of life (Titterington & Fraser, 1975 ; Lynch, 1981 ; Morrison, English & Lodge, 1983) . Piglets without straw used the forward creep box earlier and for a greater proportion of time . They seemed more thermally sensitive, spending less time in areas of the pen where there was no source of warmth from the sow or supplementary heater . The thermal resistance of a straw bedded floor is greater than bare insulated concrete (Baxter, 1981) and it has been demonstrated in metabolic studies of young piglets that provision of straw bedding has the same effect as an 8 °C temperature rise (Stephens, 1971) . Even very young piglets will select an area where the temperature is closest to their thermal requirements (Mount, 1963) and make more use of a forward creep area at lower ambient temperatures (Lynch, 1981 ; Morrison et al., 1983) . It has been noted that young piglets leave the sow most often when she terminates suckling (Petherick, 1983) so that the tendency for greater restlessness in sows without straw may have additionally contributed to the observed results. The numbers of animals used in this study were too small to evaluate effects on performance but the observed behaviours indicate that provision of straw bedding may be of value in reducing sow restlessness and consequent opportunities for crushing of piglets . Straw is a multifunctional substrate for pigs, with physical, thermal, nutritional and occupational properties . More detailed experiments are required to determine which of these properties are important for the observed effects on sow and piglet behaviour, and to gain a better understanding of the role of straw in pig welfare . ACKNOWLEDGEMENTS We thank all the staff at Terrington EHF who assisted with this study .



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