Changes in productivity and culling rate according to pregnancy feed intake and litter parity

Livestock Production Science, 17 (1987) 247-261

247

Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Changes in Productivity and Culling Rate According to Pregnancy Feed Intake and Litter Parity* F. GATEL 1, J. CASTAING2 and J. LUCBERT 3

1I. T. C.F., Pouline, ViUerable, 41100 Vendome (France) 2A.G.P.M., Montardon, 64121 Serres Castet (France) ~*I.T.C.F, 5 rue Keppler, 75116 Paris (France) (Accepted 13 January 1987)

ABSTRACT Gatel, F., Castaing, J. and Lucbert, J., 1987. Changes in productivity and culling rate according to pregnancy feed intake and litter parity. Livest. Prod. Sci., 17: 247-261. The long-term effects of the level of feeding of sows during pregnancy are not yet well documented. In two successive experiments, four levels of energy intake during pregnancy were compared: 24.7 (I); 29.9 (II); 33.2 (III); 36.6 (IV) MJ digestible energy (MJDE) day 1. Daily protein and lysine allowances were indentical for the four treatments. During lactation, sows on each treatment were allowed the same feed intake. Finally, each sow was allocated to the same treatment from the first mating until culling. A total of 790 gilts (1857 litters) were used in these two experiments. Litter size varied with parity. However, there was little relationship with energy supply during pregnancy. Piglet mortality rate depended mainly on litter size and parity; it was slightly lower when energy intake during pregnancy was low. In each experiment, the number of weaned piglets per litter was slightly higher for the most restricted sows. However, piglet weight tended to be lower with Treatment I; for the other three treatments, there was no relationship with energy intake during pregnancy. The weight change of the sows during their reproductive life was highly related to energy intake during pregnancy. The weight of the sows at weaning was consistently lower with the lowest energy allowances. However, culling rate was higher for the less restricted sows, primarily because of anoestrus problems after weaning or lameness. INTRODUCTION

The energy requirements of pregnant sows are not yet precisely known: authors agree on the effects of energy intake during pregnancy on sow weight changes (Henry and Etienne, 1978; Agricultural Research Council, 1981; Aherne and Kirkwood, 1985), but the effects on reproductive performances are rather unclear. Moreover, numerous experiments were carried out over *Orginally presented as a paper at the 36th E.A.A.P. Annual Meeting.

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© 1987 Elsevier Science Publishers B.V.

248 only one reproductive cycle, generally with first litter sows or with small numbers of animals. Fewer authors (Lodge et al., 1966a, b; O'Grady, 1967; SalmonLegagneur, 1969; Libal and Wahlstrom, 1977; Walker, 1983; Whittemore et al., 1984) have studied the long-term effects of pregnancy feed level during several consecutive parities and with a sufficient number of sows. However, the right level of energy intake must enable good reproductive performances throughout the whole reproductive life of the sow, while ensuring maximum longevity. Two experiments were designed to study further the long-term effects of different feeding level of sows during pregnancy on reproductive performances, body status and longevity. MATERIALSAND METHODS

Feeding During two successive experiments, four different daily energy intakes (24.7, 29.9, 33.2 and 36.6 MJ digestible energy (DE) day -1 for Treatments I, II, III and IV, respectively) were achieved by adjusting the intake of five diets ( Table I) so that similar intakes of protein and lysine were achieved on each dietary treatment (285 and 12 g day -1, respectively). In the first experiment, sows received Treatments I and II, whereas Treatments II, III and IV were compared in the second experiment. During lactation, sows on each treatment were subjected to the same feeding schedule, the maximum feeding level being determined by the number of piglets suckled. For a sow suckling eight piglets, maximum lactation daily allowances were ~ 62 MJ DE, 720 g crude protein and 34 g lysine. The actual quantities of feed and energy ingested during lactation by sows of the different treatments are given in Table II. The lactation diet was based on grain, bran, soya-bean meal and fishmeal. Sows were individually fed once daily during gestation and twice daily when staying in the farrowing barn, always in the form of moist meal. Water was freely available from automatic waterers. Suckling piglets were creep-fed ad libitum from 1 week of age until weaning.

Animals A total of 790 pure bred Large White gilts (324 in the first experiment and 466 in the second experiment), averaging 207 days and 115 kg weight for the first experiment and 220 days and 126 kg weight for the second experiment were randomly assigned to the different treatments after mating. The animals remained on the same diets as long as they were in the experiment.

249 TABLE I Composition and characteristics of pregnancy diets

Maize (%) Wheat (%) Barley ( % ) Bran (%) Soyabean meal ( % ) Fish meal (%) Maize starch ( % ) Mineral and vitamin ( % )

1st experiment

2nd experiment

Treatment Treatment

Treatment Treatment Treatment

I

II

II

25.4 26.8 25.5 6.0 7.6 3.0 -5.7

32.0 28.0 26.3 6.0 . 3.0 -4.7

Crude protein (g kg -~) Lysine (g kg -~ M~thionine + cystine (g kg ~ ) Crude fiber (g kg 1) Calcium (g kg-' ) Phosphorus (g kg -1)

145 6.8 5.6 30 15.0 8.3

119 5.0 4.8 29 12.4 7.4

Feed intake (kg day -1) Energy intake (MJ DE, day -1)

1.9 24.7

2.3 29.7

.

28.8 28.6 28.6 6.0 . 4.0 -4.0

III

IV

26.5 26.0 26.0 5.6

24.5 24.3 24.3 5.2

3.7 8.5 3.7

3.3 15.0 3.4

125 5.2 4.9 30 12.7 8.4

115 4.8 4.6 29 12.1 7.9

109 4.5 4.4 26 11.2 7.3

2.3 29.9

2.5 33.2

2.7 36.6

.

TABLE II Feed intake during lactation 1st experiment

Feed intake during lactation (kg day-1 ) Energy intake during lactation (MJ DE day-l)

2nd experiment

Treatment

Treatment

Treatment

Treatment

Treatment

I

II

II

III

IV

4.0

3.9

4.3

4.1

4.0

52.3

51.2

56.1

54.2

52.4

250 T A B L E III N u m b e r of sows for each reproductive cycle Cycle

1st 2nd 3rd 4th 5th 6th and above TOTAL

1st E x p e r i m e n t

2nd experiment

Treatment I

T r e a t m e n t II

T r e a t m e n t II

T r e a t m e n t III

T r e a t m e n t IV

164 103 72 34 15 -388

160 106 62 36 21 -385

150 89 66 40 15 8 368

153 81 56 36 20 19 365

163 90 55 24 13 6 351

Housing and management Sows were allocated in groups of 24 every 3 weeks. Piglets were weaned at 4 weeks of age. To ensure an intensive rate of reproduction, sows failing to return to oestrus within 15 days after weaning, or failing to conceive after mating, were systematically eliminated. As a consequence, a relatively short and constant weaning-conception interval was observed. First litter sows were mated to one of the boars of the herd, with a similar number of sows mated to each boar in each treatment. Multiparous sows were either naturally mated or artificially inseminated, with a similar proportion of sows mated by each boar of the herd or artificially inseminated in each t r e a t m e n t and for each parity. Sows were then weighed and taken to the pregnancy room where they were penned on a slatted floor. Pregnancy rooms were isolated, but not heated. In winter, the air temperature did not fall below 14 ° C, whereas it increased up to 27°C during summer. One week before parturition, sows were taken to the farrowing room, washed, weighed and placed in farrowing crates. Farrowing rooms were centrally heated with the air temperature remaining between 20 ° C in winter and ~ 30 ° C in summer. W i t h i n 24 h after parturition, sows were weighed, whereas piglets were enumerated, teeth clipped, individually weighed and earmarked. Transfer of piglets was possible only within a t r e a t m e n t and between sows of the same parity to enable correct interpretation of the results by t r e a t m e n t or by parity. For this reason, cross-fostering of piglets seldom occurred. Piglets were weighed again at weaning. RESULTS

A total of 790 gilts were used in these two experiments. For a number of reasons (anoestrus after weaning, non-conception, maternal troubles, lameness), several sows were culled after each weaning, so t h a t the number of litters analysed decreased with successive parities. However, at least 24 sows com-

251 T A B L E IV Average productivityof sows according to treatment SignifiSignifi- 2nd experiment cance cance T r e a t m e n t II T r e a t m e n t III T r e a t m e n t IV Treatment I Treatment II 1st experiment

Number of piglets born Number of weaned piglets Mortality rate (birth-weaning) Piglet birth weight {kg) Piglet weaning weight (kg) Average daily gain ( b i r t h weaning) ( g d a y ~)

10.0

9.5

*

10.6

10.7

10.3

NS

8.0

7.5

*

8.5

8.1

8.0

**

20.5

21.5

NS

19.8

23.8

22.3

**

1.17

1.27

**

1.26

1.27

1.29

NS

5.3

5.6

**

6.0

6.0

6.1

NS

153

164

**

171

172

173

NS

NS = Not significant; * = significant, P < 0.05; ** = significant, P < 0.01.

pleted four lactations on each treatment in each experiment. Table III gives the number of weaned sows for each parity.

Sow productivity The average productivity of sows given different treatments is shown in Table IV. Litter size varied according to litter parity (Fig. 1 ): it decreased from the first to the second parity and then increased until the fourth or the fifth parity. There were little differences in prolificacy due to energy supply during pregnancy. However, in both experiments the less restricted sows tended to be slightly less prolific than those on the other treatments. For all treatments, total mortality rate increased from the second to the fifth parity, together with litter size (Table V). Within an experiment, mortality rate was also slightly lower for the most restricted sows. Despite the change in litter size, the number of piglets weaned per litter was little related to parity. For each experiment, the average number of weaned piglets was slightly higher for the most restricted sows: ~ 0.5 piglet more (P<0.05 and P<0.01 for the first and the second experiment, respectively). Piglet birth weight (Fig. 2) was affected both by parity and by size of the litter; it was systematically lower for piglets farrowed by first litter sows, increased with the second and third parity and then decreased in relation to the number of piglets born. In the first experiment, there was also a significant difference ( P < 0.01 ) in piglet birth weight due to energy level during pregnancy, piglet birth weight being lower for the most restricted sows. However, this difference was not ob-

252 Number

of piglets

I2.5 BORN

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12.0.

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•

11.5.

/ //v

A. . . . . . . . . /~-

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i0.5

I0.0

/ .~' a

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9.5-

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o .................

t r e a t m e n t II ~ t r e a t m e n t III t r e a t m e n t IV 7

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9.0-

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//,"

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A.

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8.5-

8.0-

7.5 o . . . . . . . . . .

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WEANED

7.0 Reproductive

1

u

i

i

2

3

4

cycle I

5

Fig. 1. Evolution of prolificacy and number of weaned piglets according to treatment and litter parity. Except for Treatment I, piglet weaning weight (Fig. 2 ) was related to parity, multiparous sows weaning heavier piglets than first litter sows. In the first experiment, as for birth weight, weaning weight was significantly lower ( P < 0.01 ) for Treatment I, average daily gain being even lower for these piglets, but in the second experiment, there was no relation between piglet weaning weight and the level of feeding of the sows during pregnancy.

Sow weight change Sow weight changes according to litter and parity are shown in Table VI. In both experiments, total weight gain during pregnancy was significantly

253 TABLE V Total mortality rate according to t r e a t m e n t a n d litter parity ( % of piglets b o r n ) Cycle 1st experiment

Signifi- 2nd experiment Signifivance vance T r e a t m e n t I T r e a t m e n t II T r e a t m e n t I! T r e a t m e n t III T r e a t m e n t III

1st 2nd 3rd 4th 5th

19.2 17.1 20.8 28.6 31.6

20.5 17.6 20.1 32.2 23.9

NS NS NS NS NS

17.8 16.2 20.1 28.9 24.6

17.9 21.0 25.9 29.9 37.2

20.6 19.2 24.7 25.4 32.9

NS

NS

NS = N o t significant, P > 0.05; * = significant, P < 0.05. T A B L E VI Sow weight changes according to t r e a t m e n t a n d litter parity 1st experiment Treatment I N e t pregnancy gain 1st cycle 39.8 2nd cycle 18.0 3rd cycle 10.9 4th cycle 3.4 5th cycle 2.4 6th cycle -Lactation weight losses 1st cycle 18.6 2nd cycle 21.5 3rd cycle 23.9 4th cycle 23.7 5th cycle 14.7 6th cycle -M a t i n g - w e a n i n g weight gain 1st cycle 21.2 2nd cycle - 3.5 3rd cycle - 12.6 4th cycle -20.3 5th cycle - 12.3 6th cycle -Weaning weight of sows 1st cycle 136.4 2nd cycle 143.7 3rd cycle 142.8 4th cycle 141.5 5th cycle 147.4 6th cycle --

2nd experiment T r e a t m e n t II

T r e a t m e n t II

T r e a t m e n t III

T r e a t m e n t IV

47.9 33.9 26.9 16.5 11.9 --

47.6 37.3 30.9 25.3 23.8 16.3

53.7 45.7 37.8 34.5 26.6 32.5

59.3 53.6 44.9 41.9 37.4 40.7

18.9 25.8 27.1 27.5 28.5 --

23.2 27.3 28.2 26.1 24.3 25.7

24.0 24.6 27.3 28.3 26.6 24.3

23.6 26.9 30.5 27.5 31.9 36.5

29.0 8.2 -0.2 -11.0 - 16.6 --

24.4 10.1 2.7 -0.8 -0.5 - 9.4

29.7 21.1 10.5 6.1 0 8.2

35.6 26.7 14.4 14.4 5.5 4.2

143.6 160.2 171.0 171.9 163.9 --

151.3 170.7 185.6 196.2 196.2 189.4

154.6 185.5 202.4 216.6 215.5 234.2

161.4 197.0 217.8 231.7 233.1 236.2

254 Average piglet weaning-weight (kg) 7.0

6.5

6.0 /4

""" o - . 5.5

5.0

I4.5

Reproductive cycle

Average piglet birth weight (kg)

first e x p . treatment I treatment II second exp.

1.5'

1.4"

I / /

-~:'-~

...x'/ ~

1.3-

.

t r e a t m e n t II t r e a t m e n t III t r e a t m e n t IV

:~=~-.~:

A.... A O- - --O = ":

"-,

~-----~---.

1.2.

1.1.

1.0

Reproductive cycle i

i

t

l

2

3

.

.

.

.

.

.

.

.

T

4

. . . .

1

5

Fig. 2. Evolution of piglet weight according to treatment and litter parity. higher ( P < 0.01 ) when energy intake during pregnancy increased. Moreover, it decreased evenly with successive parities for every treatment. Parturition weight losses seemed to be rather independent of treatment or parity. Therefore, variations of net weight gain during pregnancy were similar to those of total weight gain, with a regular decrease from the first to the fifth cycle and a significant difference ( P < 0.01 ) between treatments. In the first experiment, lactation weight losses of first litter sows were similar for both treatments. Subsequently, they were systematically lower for the most restricted sows. In the second experiment, however, there was no correlation between lactation weight losses and treatment or parity.

255 T A B L E VII Causes of culling of sows ( % of culled sows) Cause

A n o e s t r u s after weaning R e t u r n to heat Abortion Maternal problems Lameness E n d of e x p e r i m e n t Miscellaneous

1st e x p e r i m e n t

2nd e x p e r i m e n t

Treatment I

T r e a t m e n t II

T r e a t m e n t II

T r e a t m e n t III

T r e a t m e n t IV

25.5 17.0 13.3 3.7 22.3 18.2 --

25.7 26.8 5.0 3.9 22.9 15.7 --

16.7 24.7 -10.0 21.3 8.0 19.3

16.3 22.9 -13.1 20.9 4.6 22.2

23.3 22.7 -8.6 28.2 6.2 11.0

In the first experiment, weight gain between mating and subsequent weaning became negative from the second or the third parity ( for Treatments I and II, respectively) as lactation weight losses became greater than pregnancy net weight gain. Weight of sows at weaning, which was systematically lower for Treatment I, increased until the second or the third weaning and then remained steady or decreased slightly. A systematic weight gain during the weaning-conception interval should be noted. For the second experiment, weight gain between mating and subsequent weaning decreased with successive parities and thus became null at the third, fifth and sixth weaning for Treatments II, III and IV, respectively. For all treatments, weight of sows at weaning increased regularly until the fourth weaning and then remained steady. Differences between treatments were significant from the first weaning and then increased (Table VI). Longevity of sows At the end of each experiment, some sows were eliminated because of the ending of the experiment, but we made sure that there was an equal number of sows culled for this reason for each treatment within an experiment ( ~ 17% in Experiment I and 6% in Experiment 2 ). On average, 40% of the sows were culled after the first reproductive cycle and 60% failed to produce more than two litters during their reproductive life. The rate of culling was similar for both treatments. On the contrary, in the second experiment, the rate of culling seemed to increase with the level of energy intake during pregnancy. In particular, sows of Treatment IV were culled at a faster rate than sows of the other two treatments. Looking at the causes of culling ( Table VII ), it appears that the main causes were, for the first experiment, anoestrus after weaning and lameness and, for Treatment II, non-conception after mating. Abortion was also of special im-

256 portance for Treatment I. For the second experiment, lameness, return to heat and anoestrus after weaning were the main causes of culling, with emphasis on anoestrus and lamaness for Treatment IV. DISCUSSION For practical reasons, only pure bred sows were used in the experiments. This could partly explain why productivity was relatively low by today's commercial standards. Increase in litter size with successive parities has been observed for a long time by several authors (Lodge, 1969; Legault et al., 1975). More recently, it was pointed out, that as observed here, litter size may drop at the second parity and then increase progressively, as in the classical pattern (Dagorn et al., 1984; Gadd, 1984; Lucbert and Lavorel, 1984; Hall et al., 1985; Clark and Leman, 1986; Esbenshade et al., 1986). Within each experiment, prolificacy decreased slightly when energy intake during pregnancy increased, as shown by Frobish et al., (1966), Mayrose et al. (1966) and Libal and Wahlstrom (1977). In a literature review, Van Spaendonck (1974) suggested that on either side of an optimum level, a too low or too high pregnancy energy level would decrease the number of piglets born per litter. However, the difference in litter sizes achieved with Treatment II in the first and the second experiment makes it difficult to compare results, irrespective of the experiment. Mortality rate of piglets increased with parity, but was not higher with the most restricted sows, which have the largest litters. However, in the latter case, most of the mortality occurred in the first hours after farrowing, with puny or crushed piglets, while with less restricted sows, mortality between 48 h postfarrowing and weaning was more important. Piglet birth weight was related to parity and size of litter and also, for the first experiment, to energy level during pregnancy. The latter is in agreement with current findings in the literature ( Henry and Etienne, 1978; Aherne and Kirkwood, 1985 ). Henry and Etienne (1978) showed that the increase in piglet birth weight with increasing energy level in pregnancy was most obvious with multiparous sows. This suggests that there is a cumulative effect of energy level during pregnancy on growth of foetuses with successive parities. In the first experiment, the difference between piglet birth weights, which is only 30 g at the first parity, increased regularly up to 250 g at the fifth parity. However, in the second experiment, with higher levels of feeding no effect of energy level during pregnancy on piglet birth weight was observed, which suggests that above some threshold level energy level during pregnancy would have little effect on piglet birth weight. This is confirmed by the review of the Agricultural Research Council (1981), where response of piglet birth weight to pregnancy

257 energy allowances appears to be, over a wide range of energy intake, more curvilinear than linear. Piglet weaning weight seemed well correlated with birth weight, for it was lower with first litter sows and in the first experiment with the most restricted sows. Etienne (1979) pointed out that energy intake during pregnancy affects lactation performance of the sow as well as piglet birth weight. Moreover, heavier piglets at farrowing should be more active for suckling or creep feeding and should, therefore, have a better post-natal development than lighter piglets. The effects of energy intake during pregnancy on sow weight change have been highlighted by a number of authors ( Lodge et al., 1966b; Libal and Wahlstrom, 1977 ) ; Henry and Etienne (1978) demonstrated a correlation coefficient of 0.9 between energy intake and total weight gain. Parturition weight losses were unaffected by treatment, as previously shown by Salmon-Legagneur (1969). Therefore, pregnancy net weight change increased with energy intake during pregnancy, in agreement with Frobish et al. (1966), Lodge et al. (1966b), Mayrose et al. (1966), Elsley et al. (1969), Frobish et al. (1973), Elliot and Lodge (1978), Walker (1983), Whittemore et al. (1984). On the other hand, Lodge et al. (1966), Elsley et al. (1969), Frobish et al. (1973), Esbenshade et al. (1986) reported a progressive decrease in pregnancy net weight change with successive parities, which was also observed in the present experiments. This is probably in relation to the fact that for each treatment all sows were submitted to the same rate of feeding, irrespective of parity. As maintenance requirement increases with age and weight (Agricultural Research Council, 1981 ), a more and more important part of the energy ingested must have been used for maintenance instead of weight gain with successive parities. Moreover, even though similar protein allowances were given on each treatment, the partitioning of protein is likely to have changed considerably with the different energy level and more particularly with the increasing demand for energy for maintenance. In the first experiment, lactation weight losses were lower with the most restricted sows, which had a lower weight gain during gestation, in agreement with Lodge et al. (1966b) and Walker (1983). Nevertheless, in the second experiment there was no correlation between lactation weight losses and treatment of parity. It is possible that when feed restriction during pregnancy is not too severe, body status of the sows enables them to complete a normal lactation without any difference according to treatment. However, it is difficult to compare the two experiments for these criteria as there were some differences in weight of gilts at first mating and in lactation feed intake. This may explain the discrepancies in weaning weight of the sows subjected to Treatment II in Experiments 1 and 2. The weight difference between these two groups increased with increasing parity number, the higher

258 values being obtained in the second experiment, despite a probably higher milk production, as indicated by more numerous and heavier piglets at weaning. Culling rate was higher than generally reported (Dagorn and Aumaitre, 1979; Kroes and Van Male, 1979), The high rate exhibited in these two experiments is partially explained by the culling policy applied. However, such a high culling rate, particularly in the early parities, has also been reported by Pattison (1980). Culling rate was not affected by t r e a t m e n t in the first experiment, but was slightly higher for the less restricted sows in the second experiment. However, Walker (1983), who compared energy allowances through five gestations, found a higher culling rate for the most restricted sows. In contrast, Frobish et al. (1973) with four levels of energy allowance during pregnancy (12.5-31.4 MJ ME day 1, compared over three reproductive cycles, observed a significantly lower percentage of sows completing three reproductive cycles for the less restricted group. For this group, leg abnormalities were the major factor causing removal, which is fairly consistent with our observations in T r e a t m e n t IV. Nielsen and Danielsen (1984) also observed with gilts fed different levels of energy before mating that restricted gilts lasted longer in the herd than gilts fed more liberally. The reason for this was primarily that more young sows had to be culled due to leg problems in the group fed medium and high levels of nutrition during rearing. Hardy and Lodge (1969) and Frobish et al. (1973) pointed out the special importance of return to heat as a removal cause for the most restricted sows; however, in a previous experiment, Frobish et al. (1966) observed that half of the sows fed a very high level of energy intake during pregnancy (45.1 MJ ME day 1) were removed from the experiment by the end of three reproductive cycles because of death or failure to farrow. At slaughter, an extremely large amount of fatty tissue could be seen around the reproductive organs. In the experiment reported here, no differences in failure to conceive were observed in the second experiment, whereas in the first experiment, the second t r e a t m e n t exhibited the highest rate of return to heat. Yet this group was certainly not overfed. Finally, sows of T r e a t m e n t I or even II who completed five reproductive cycles were very thin and emaciated at the end of the experiment. However, none was eliminated for this reason, whereas Libal and Walhstrom (1977), in the course of a winter trial, were obliged to remove several sows submitted to severe restriction (16.7 MJ ME d a y - 1) because of their emaciated conditions. This indicates that although they do not cause any removal, T r e a t m e n t s I and II, resulting in poor condition animals, are factors of fragility and risk. CONCLUSIONS Although a severe energy restriction in gestation ( Treatments I and II ) does not decrease litter size and number of piglets weaned per litter, it decreased

259

piglet weight at both birth and weaning. On the other hand, these treatments did not change culling rate, but they led to very thin sows. It could be accepted in experimental conditions where every factor is controlled, but it could not be recommended in commercial breeding. Conversely, a very high energy intake (Treatment IV) did not increase numerical productivity and led to an increased rate of culling, associated with lameness or anoestrus after weaning. Hence, in our conditions, a moderate energy intake, as in Treatment III, can be recommended without any important risks. However, the level of feeding during pregnancy should be considered in relation to the level of feeding during lactation and the weaning-mating interval, body status and the type of gilt (breed, age, weight) at first mating, environmental conditions and also with economic consideration of the different factors enumerated above: number of piglets, weight of piglet, weight of sow.

REFERENCES Agricultural Research Council, 1981. The nutrient requirements of pigs. Commonwealth Agricultural Bureaux. Aherne, F.X. and Kirkwood, R.N., 1985. A review. Nutrition and sow prolificacy. J. Reprod. Fertil. (Suppl.), 33: 1-15. Clark, L.K. and Leman, A.D., 1986. Factors that influence litter size in pigs: Part 1. Pig News Inf., 7: 303-310. Dagorn, J. and Aumaitre, A., 1979. Sow culling: reasons for and effect on productivity. Livest. Prod. Sci., 6: 167-177. Dagorn, J., Saulnier, J. and Greau, P., 1984. Evolution et variation de la prolificit~ entre la premiere et la seconde pottle. J. Rech. Porcine France, 16: 145-152. Elliot, J.I. and Lodge, G.A., 1978. Severe restriction of the sow during late pregnancy. Can. J. Anita. Sci., 58: 43-48. Elsley, F.W.H., Bannerman, M., Bathurst, E.V.J., Bracewell, A.G., Cunningham, J.M.M., Dodsworth, T.L., Dodds, P.A., Forbes, T.J. and Laird, R., 1969. The effect of feed intake in pregnancy and in lactation upon the productivity of sows. Anim. Prod., 11: 225-241. Esbenshade, K.L., Britt, J.H., Armstrong, J.D., Toelle, V.D. and Stanislaw, C.M., 1986. Body condition of sows across parities and relationship to reproductive performance. J. Anim. Sci., 62: 1187-1193. Etienne, M., 1979. Influence de l'alimentation des truies gravides sur l'~volution des r~serves corporelles maternelles et le d~veloppement de la port~e. Ann. Biol. Anim. Biochem. Biophys., 19: 289-308. Frobish, L.T., Speer, V.C., Hays, V.W., 1966. Effect of protein and energy intake on reproductive performance in swine. J. Anim. Sci., 25: 729-733. Frobish, L.T., Steele, N.C. and Davey, R.J., 1973. Long term effect of energy intake on reproductive performance of swine. J. Anim. Sci., 36: 293-297. Gadd, J., 1984. Second thoughts on second-litter sows. Pig Farming, April 1984, 52-53. Hall, D.D., Cromwell G.L., Prince, T.J., Knabe, D.A., Clawson, A.J., Maxwell, C.V., Noland, P.R., Orr, D.E. and Combs, G.E., 1985. Depletion of body fat reserves: an explanation for decreased second parity prolificacy in sows. J. Anim. Sci., 61, suppl. 1,316, Abstract.

260 Hardy, B. and Lodge, G.A., 1969. The effect of body condition on ovulation rate in the sow. Anim. Prod., 11: 505-510. Henry, Y. and Etienne, M., 1978. Alimentation dnerg~tique du porc. J. Rech. Porcine France, 10: 119-166. Kroes, Y. and Van Male, J.P., 1979. Reproductive lifetime of sows in relation to economy of production. Livest. Prod. Sci., 6: 179-183. Legault, C., Dagorn, J., Tastu, D., 1975. Effets du mois de mise-bas, du numdro de portde, et du type g~n~tique de la m~re sur les composantes de la productivit~ des truies dans les ~levages franqais. J. Rech. Porcine France, 7: XLIII-LII. Libal, G.W. and Wahlstrom, R.C., 1977. Effect of gestation metabolizable energy levels on sow productivity. J. Anim. Sci., 45: 286-292. Lodge, G.A., 1969. The effect of pattern of feed distribution during the reproductive cycle on the performance of sows. Anim. Prod., 11: 133-143. Lodge, G.A., Elsley, F.W.H. and MacPherson, R.M., 1966a. The effects of level of feeding of sows during pregnancy. I. Reproductive performance. Anim. Prod., 8: 29-38. Lodge, G.A., Elsley, F.W.H. and MacPherson, R.M., 1966b. The effects of level of feeding of sows during pregnancy II changes in body weight. Anim. Prod., 8: 499-506. Lucbert, J. and Lavorel, O., 1984. Baisse de prolificit~ de la truie en seconde portde: analyse des donnSes de deux ~levages expdrimentaux. J. Rech. Porcine France, 16:115-124. Mayrose, V.B., Speer, V.C. and Hays, V.W., 1966. Effect of feeding levels on the reproductive performance of swine. J. Anim. Sci., 25: 701-705. Nielsen, H.E. and Danielsen, V., 1984. Nutrition and breeding lifetime. 35th Annual Meeting of the EAAP, at The Hague, The Netherlands, 6-9 August 1984. O'Grady, J.F., 1967. Effect of level and pattern of feeding during pregnancy on weight change and reproductive performance of sows. Ir. J. Agric. Res., 6: 57-71. Pattison, H.D., 1980. Patterns of sow culling. Pig News Inf., 1: 215-218. Salmon-Legagneur, E., 1969. Influence ~ long terme du rationnement des truies gestantes. J. Rech. Porcine France, 1: 77-81. Van Spaendonck, R., 1974. Besoins en dnergie et en protdines des truies en gestation et des truies en lactation. Rev. Agric., 5: 1069-1098. Walker, N., 1983. The effects of food intake in gestation on sows lactating for 14 days. Anim. Prod., 37: 25-31. Whittemore, C.T., Taylor, A.G., Hillyer, G.M., Wilson, D. and Stamataris, C., 1984. Influence of body fat stores on reproductive performance of sows. Anim. Prod., 38: 527, Abstract. RESUME Gatel, F., Castaing, J. and Lucbert, J., 1987. l~volution de la productivit~ et du taux de r~forme des truies en fonction du num~ro du cycle et des conditions d'~levage. Livest. Prod. Sci., 17: 247-261 (en anglais). Les effets ~ long terme du niveau de rationnement Snerg~tique des truies en gestation sont encore mal connus. Lors de deux essais successifs, nous avons compar~ quatre niveaux de rationnement 6nergStique en gestation: 24.7 (I); 29.9 (II); 33.2 (III); et 36.6 (IV) M.J.E.D. jour 1; les apports journaliers de prot~ines et de lysine dtaient similaires quel que soit le traitement. En lactation, tousles animaux 6taient soumis au m~me rationnement. Enfin, chaque truie ~tait soumise au m~me traitement depuis la premiere saillie jusqu'~ la r~forme. Les deux essais ont port~ au total sur 790 truies, soit 1857 port~es. La prolificit~ varie selon le numSro du cycle; elle appara]t par contre peu lide aux apports ~nergdtiques de gestation. Le taux de mortalit~ des porcelets varie principalement avec la taille de la

261 portde et le cycle de la truie; il est aussi ldg~rement plus faible lorsque le rationnement est plus s~v~re en gestation. Dans chaque essai, le hombre de porcelets sevrds par port~e est ldg~rement plus dlevd pour les animaux les plus rationnSs. Par contre, le poids des porcelets tend h ~tre plus faible avec te Traitement I; mais pour les trois autres traitements, il n'apparalt pas lid au rationnement en gestation. L'dvolution ponddrale des truies au cours de leur carri~re est directement lide aux quantit~s d'dnergie consomm~es en gestation. Le poids des truies au sevrage est toujours plus faible avec l'apport dnergdtique le plus bas. Cependant, le taux de rdforme est plus dlevd chez les truies les moins rationndes, en liaison avec des probl~mes d'anoestrus apr~s sevrage ou des troubles de locomotion. KURZFASSUNG Gatel, F., Castaing, J. und Lucbert, J., 1987. ~,nderungen der Produktivit~t under Merzungsrate in Abhiingigkeit von Futteraufnahme w~ihrend der Tr~ichtigkeit und Wurfzahl. Livest. Prod. Sci., 17:247-261 (auf englisch). Langfristige Auswirkungen des Ftitterungsniveaus von Sauen w~ihrend der Tragezeit sind nicht gut nachgewiesen. In zwei aufeinander folgenden Versuchen wurden vier Niveaus der Energieversorgung wiihrend der Triichtigkeit verglichen: 24.7 ( I ), 29.9 ( II ), 33.2 (III) und 36.6 (IV) M.J. verdauliche Energie pro Tag. Die tiigliche Versorgung mit Protein und Lysin war in allen vier Behandlungen gleich. W~hrend der Laktation wurde den Sauen aller Behandlungen die gleiche Futteraufnahme ermSglicht. Jede Sau blieb in der Behandlungsgruppe von der ersten Besamung bis zur Merzung. Insgesamt wurden in diesen zwei Versuchen die Daten von 790 Jungsauen bzw. 1857 Wiirfen ausgewertet. Die WurfgrSt~e ~inderte sich mit der Wurfzahl. Hier bestand jedoch kaum eine Beziehung zur Energieversorgung wiihrend der Triichtigkeit. Die Ferkelsterblichkeit hing vor allen Dingen von der WurfgrSi~e und der Wurfzahl ab; sie war jedoch etwas geringer, wenn die Energieaufnahme wiihrend der Triichtigkeit niedrig war. In jedem Versuch war die Zahl der abgesetzten Ferkel pro Wurf etwas h~her ffir die Sauen mit der niedrigsten Aufnahme in der Triichtigkeit. Es war jedoch eine Tendenz zu niedrigerem Ferkelgewicht in Behandlung I; ftir die anderen drei Behandlungen bestand keine Beziehung zur Energieaufnahme wiihrend der Triichtigkeit. Gewichtsver~inderungen der Sauen wiihrend der reproduktiven Phase war stark korreliert mit der Energieaufnahme wiihrend der Tragezeit. Das Gewicht der Sauen zum Zeitpunkt des Absetzens war wesentlich niedriger in den Sauen mit der niedrigsten Energieaufnahme. Jedoch war die Merzungsrate hSher fiir die weniger restriktiv gefiitterten Sauen vor allen wegen anoestrus Problemen nach dem Absetzen oder wegen Beinschiiden.