Growth rate and protein and fat gain in early-weaned piglets housed below thermoneutrality

Growth rate and protein and fat gain in early-weaned piglets housed below thermoneutrality

Livestock Production Science, 9 (1982) 731--742 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands 731 GROWTH RATE AND ...

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Livestock Production Science, 9 (1982) 731--742 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

731

GROWTH RATE AND PROTEIN AND FAT GAIN IN EARLY-WEANED PIGLETS HOUSED BELOW THERMONEUTRALITY

J. LE DIVIDICH and J. NOBLET Institut National de la Recherche Agronomique, Station de Recherches sur l'Elevage des Porcs, Centre de Rennes-St Gilles, 35590 l'Hermitage (France) (Accepted 8 March 1982)

ABSTRACT Le Dividich, J. and Noblet, J., 1982. Growth rate and protein and fat gain in early-weaned piglets housed below thermoneutrality. Livest. Prod. Sci., 9: 731--742. Two trials involving 78 piglets were conducted over a period of six weeks, following weaning at approximately three weeks of age, in order to determine the effect of cold temperatures on growth depression and on the protein (N × 6.25) (P) and fat (F) deposition in individually-housed piglets. The temperature patterns and mean daily food intakes were 32--26, 28--22, 24--18°C and 81 g/kg °'~5 (Trial I); 28--22°C and 73 and 62 g/kg °'75, 24--18°C and 100 and 74.5 g/kg °'Ts (Trial II). Depositions of protein and fat were determined by the comparative slaughter technique. Growth rate increased with each unit of daily food intake (1 g/kg °'75) by 7.67 -+ 0.72 g/day. This value did not vary significantly with temperature. At a constant level of food intake of 80 g/kg°'TS/day, the growth rate of piglets and the gain: food ratio were similar in the 32--26 and 28--22°C environments and significantly higher than at 24--18°C. Growth rate decreased on average by 12.2 g per l°C fall in temperature below 28--22°C. Daily P and F were increased by 0.98 -+ 0.10 and 1.24 -+ 0.10 g/day per unit increment in food intake, respectively. These regression coefficients did not vary significantly with temperature. At a constant level of food intake, P and F decreased by 1.30 and 1.35 g/day per I°C fall in temperature below 28--22 ° C, respectively. The protein content of the empty body weight gain increased with each decrease in daily food intake by 0.09 + 0.02% and the fat content fell correspondingly by 0.23 -+ 0.03%. These regression coefficients did not vary significantly with temperature.

INTRODUCTION

The temperature recommendation for piglets weaned at 21 days of age and reared in intensive m o d e m conditions is normally an initial of 26--28°C reducing gradually to 19--20°C by 8--9 weeks of age (Brent et al., 1975; Le Dividich, 1981). Below thermoneutrality (TN), unless food intake is increased growth rate decreases as a result of an increased heat loss leading to a reduction of metabolizable energy available for growth. However, the increasing cost of fossil energy necessary to provide supplementary heating increases interest about growth depression below TN and the extra food required to

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732 prevent this depression. The cost of the extra food can then be compared to that of heating at optimum. The extent to which growth rate is reduced below TN depends upon the effect of cold temperature on protein and fat deposition. In the growing-finishing pigs, energy retained as protein is found to be less affected by cold temperatures than energy retained as fat (Close, 1980) and the depression in daily weight gain is in the range of 10 to 24 g/°C below TN (Fuller and Boyne, 1971 ; Verstegen et al., 1977, 1979; Bresk and Stolpe, 1979). In the weaned piglets the data available are very limited. Holmes and Close (1977) calculated that the weight gain reduction would be more seriously affected in piglets as compared to heavier animals. The objectives of this study were to determine: (1) the extent of growth depression in early weaned piglets reared below TN and the extra f o o d required to prevent this depression, (2) the effects of environmental temperature on the composition of the weight gain. The results concerning the energy metabolism in relation to environmental temperature were presented in the first paper of this series (Noblet and Le Dividich, 1982). MATERIALS AND METHODS The measurements presented here were made on the seventy eight piglets of the t w o trials described by Noblet and Le Dividich (1982), where details of animals, diet and feeding scales, housing and environmental conditions and procedures are given. The design of the two trials, the number of piglets per treatment, their mean age and weight at weaning, the levels of food intake and the temperature patterns are shown in Table I. In brief, Trial I involved three air temperature patterns (24--18, 28--22 and 32--26°C) and one level of food intake (100 g/kg°'TS/day). Trial II was designed in combination with Trial I to show the effects of the level of f o o d intake and to establish the presence or absence of an interaction with temperature. Two temperature patterns were used (24--18 and 28--22°C) since results of Trial I showed that the 32--26 and 28--22°C environments resulted in similar performance. At each of the t w o temperature patterns, t w o levels of food intake were associated, 70 and 85 g/kg°'TS/day at 28--22°C and 85 and 115 g/kg°'Ts/ day at 24--18°C. These levels of f o o d intake (70, 85, 100 and 115 g/kg°'~s/ day) corresponded to maximum intakes attained during the fourth week of each trial, each of six weeks duration. The f o o d provided 0.21 g crude protein and 14.1 KJ ME per g. Piglets were weighed at weaning, at the end of the first week following weaning and subsequently on Tuesday and Friday of each week. From these weighings the mean weight of each pig over the experimental period was estimated on a daily basis and daily metabolic weight (kg °'Ts) was c o m p u t e d and integrated over the experimental period for the calculation of mean metabolic size. At the end of the trials, the piglets were killed and the gut contents were

733

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734 removed. Subsequently the deep frozen carcasses were minced and homogenized for chemical analysis. Protein content (N × 6.25) was determined by the macroKjeldahl method, ash by mineralization at 550°C for 8 h and energy by adiabatic b o m b calorimeter. Fat content was calculated by the difference between dry matter and protein plus ash. This estimation was satisfactory since the difference in b o d y energy calculated from protein and fat content and that measured by b o m b calorimetry did n o t exceed 0.3%. Both the initial e m p t y b o d y weight (EBW) (live weight less gut contents) and chemical composition of surviving piglets were predicted from the determined compositions of piglets slaughtered at Day 0. It was assumed that both the initial EBW as a proportion of live weight and the chemical composition of the EBW of live piglets were similar to the compositions of the littermate piglet killed at Day 0. The data from the two trials were analysed together by covariance using initial b o d y weight (W) and daily food intake (g/kg °'Ts) as covariates for each temperature (T). A model was fitted with T, W and food intake and the slopes of W and f o o d intake were used to make a covariance adjustment of the data. These data were then subjected to a randomized block analysis (block = litter) using either data of Trial I comparing the three air temperature patterns and extracting linear and quadratic effects of temperature, or all data comparing the two lower temperatures. The data were adjusted to a comm o n initial b o d y weight of 6 kg and to a c o m m o n f o o d intake of 80 g/kg °'Ts per day corresponding to the overall daily mean f o o d intake. This level of f o o d intake corresponded to a b o u t 80--85% of the ad libitum intake calculated from the results of Leibbrandt et al. (1975b), Kornegay et al. (1979) and S~ve (1980b) on piglets of similar weight range. The interactions between temperature and food intake were either n o t significant or marginal, so they were not taken into account. The effects of cold and of a low food intake may thus be regarded as essentially additive. RESULTS

Growth performance During Period I (Weeks 1 and 2) average daily gain (ADG) and gain to food ratio (GFR) responded linearly (P < 0.05) to increasing environmental temperature (Fig. 1). In both Periods II (Weeks 3 and 4) and III (Weeks 5 and 6) ADG and G F R were similar in the 32--26 and 28--22°C environments and higher (P < 0.05) than in the 24--18°C environment. From Period I--III, G F R decreased linearly (P < 0.05} in piglets maintained at 32--26°C and remained practically constant in those housed at 28--22°C, whereas a quadratic response (P < 0.05) was found in piglets maintained at 24--18°C. The coefficient of regression relating G F R to food intake did not vary significantly with temperature. G F R increased significantly (P < 0.05) by 0.009 + 0.002 unit per 1 g/kg °'Ts increase in daily food intake during Period I,

735 Gain Food

ADG, g 500

0.80 400

300

0.75 0.70 0.65

200

0.6, 100 1

i

1"

t

6 weeks i periods

Fig. 1. A c c u m u l a t i v e average daily gain ( A D G ) and gain per unit o f f o o d (gain/food) for w e a n e d piglets housed at 24w18°C ( c - - • ...... ) 28--22°C (A • ..... ) and 32--26°C (o ). O p e n symbols and straight lines indicate the results of Trial I, solid symbols and b r o k e n lines indicate the results of Trial I (the t w o lower temperatures) and Trial II. The data are adjusted to a c o m m o n initial b o d y weight and to a c o m m o n daily f o o d intake of 6 kg and 50 g/kg °'Ts, 8 kg and 85 g/kg °'Ts, and 13 kg and 90 g/kg °'Ts on Periods 1, 2 and 3, respectively.

but no significant relationship between GFR and food intake was found in the subsequent periods. For the overall experiment, ADG and GFR were similar in piglets housed at 32--26 and 28--22 and significantly higher (P < 0.05) than in piglets maintained in the 24--18°C environment (Table II). The coefficient of regression relating ADG to food intake did not vary significantly with temperature, ADG decreased significantly (P < 0.05) by 7.67 + 0.72 g per 1 g/kg °'Ts T A B L E II Effect of e n v i r o n m e n t a l t e m p e r a t u r e on the overall p e r f o r m a n c e of piglets* E n v i r o n m e n t a l t e m p e r a t u r e (°C)

Average daily gain (g) Gain to f o o d ratio

24

28

32

18

22

26

303 a*** 356 b 352 b (310) a (355) b 0.646 a 0.718 b 0.724 b (0.649) a (0.710) b

*Data adjusted to a c o m m o n initial b o d y weight o f 6 o f 80 g/kg°'~S/day. Data w i t h o u t parentheses indicate parentheses refer to pooled results o f Trial 1 (the t w o * * S t a n d a r d error of difference of means. ***Means in the same row w i t h different superscripts

SED**

10.9 (8.5) 0.018 (0.015)

kg and to a c o m m o n f o o d intake the results o f Trial 1, those in lower temperatures) and Trial II. are significantly different (P < 0.05)

736

decrease in daffy food intake; there was no significant relationship between G F R and food intake. Assuming a linear effect of temperature on rate of gain at a constant feeding level, reducing the air temperature from 28--22 to 24--18°C involved a mean decrease of 12.2 g in ADG per I°C fall in temperature. Reducing the air temperature by 1°C between 28--22 and 24--18°C was therefore equivalent to a reduction in daily food intake of 1.6 g/kg °'Ts (i.e., 12.2/7.67). Thus the daily food intake must be increased by 1.6 g/kg °'Ts per I°C coldness in order to give similar growth rate as in the 28--22°C environment.

Protein and fat gain Daily protein deposition (P, g/day) determined by the comparative slaughter technique and daily fat deposition (F, g/day) estimated by difference (dry matter less protein and ash) are presented in Table III. P was similar in piglets housed in the 32--26 and 28--22°C environments and both environments resulted in higher (P < 0.05) P than the 24--18°C environment. Similarly to P, F was lower (P < 0.05) in piglets housed at 24--18°C than in those housed at 32--26 and 28--22°C. Reducing the environmental temperature from 28--22 to 24--18°C involved a decrease in P and F of 1.30 and 1.35 g/day on average per I°C fall in temperature, respectively. The corresponding percentage decrease of P was 2.3%, that of F was 5.3%. TABLE III Protein and fat gain in relation to environmental temperature Environmental temperature (°C)

Protein (g/day) Fat (g/day)

24

28

32

18

22

26

51.2 a (52.9) a 18.9 a (20.5) a

57.1 b (57.8~ b 25.2 (25.3) b

58.3 b 26.25

SED

2.81, L* (1.66) 2.87, L* (2.11)

See the footnotes for Table II. L* = significant (P < 0.05) linear effect of temperature.

In order to estimate the growth associated with the deposition of P and F, ADG (Y, g) was related to P (g/day) and F (g/day) by multiple regression. The c o m m o n equation was as follows Y = 4.5 (+ 0.3) P + 1.7 (-+ 0.3) F + 49 (n = 60, R 2 = 0.85) This indicated that deposition of 1 g P and F caused a weight gain of 4.5 and 1.7 g, respectively.

(1)

737

Both P and F were highly dependent on food intake. The coefficients of regression relating P and F to f o o d intake did n o t vary significantly with temperature. The c o m m o n regressions relating P (g/day) and F (g/day) to food intake (X, g/kg°'TS/day) were P = 0.98 (+ 0.10) X - - 2 4

(n=60, r=0.84)

(2)

F=1.24(+

(n=60, r=0.92)

(3)

0.10) X - - 7 5

It appeared that F was more dependent on f o o d intake than P although the slopes of regressions were significant at only P < 0.10. For example, P was increased by 36% when feeding level was increased from 80 to 100 g/kg°'Ts/ day, whereas F was increased by 103%.

Chemical composition of the empty body weight gain (EBWG) Table IV summarizes the chemical composition of the EBWG. The percentage of protein did n o t vary significantly with environmental temperature. Decreasing the environmental temperature involved a linear decrease (P < 0.05) in the percentage of fat and energy c o n t e n t and a linear increase (P < 0.05) in the percentage of ash. The effect of decreasing daily food intake was to increase significantly (P < 0.05) the percentage of protein and ash by 0.09 + 0.01 and 0.02 + 0.004% per 1 g/kg°'TS/day, respectively. Contrarily, the percentage of fat and the energy content of gain was reduced (P < 0.05) by 0.23 + 0.03% and 0.07 + 0.01 KJ/g per 1 g/kg°'TS/day, respectively. T A B L E IV C h e m i c a l c o m p o s i t i o n o f t h e e m p t y b o d y w e i g h t gain in r e l a t i o n t o e n v i r o n m e n t a l t e m perature E n v i r o n m e n t a l t e m p e r a t u r e (°C)

P r o t e i n (%) F a t (%) Ash (%) Energy (KJ/g)

24

28

32

18

22

26

17.97 a (18.02) a 6.64 a (6.71) a 3.52 a (3.49) a 6.64 a (6.78) a

17.35 a (17.59),a 7.33 au (7.36~ a 3.35 ~ (3.36) b 6.82 aD (6.97) a

17.80 a

See t h e f o o t n o t e s for Table II. L* = significant (P < 0.05) linear e f f e c t o f t e m p e r a t u r e .

8.06 b 3.20 b 7.32 b

SED

0.40 (0.27) 0.64 L* (0.45) 0.08 L* (0.07) 0.24 L* (0.22)

738 DISCUSSION In the present experimental conditions growth performance of piglets was maximised over the temperature ranges of 28--22 to 32--26°C, although previous results obtained on the same animals (Noblet and Le Dividich, 1982) indicated that the heat production was minimal at 32--26°C. However, as mentioned by Mount (1973) the temperature range which is neutral for metabolism does not necessarily coincide with that at which growth is optimal. From the present results it can be reasonably assumed that the 28-22°C environment is very close to the lower limit of the temperature range which is optimal for growth. Below this limit the rate of gain of piglets is depressed by 12.2 g/day per I°C coldness. This estimate agrees with the 14 g calculated by Close (1980) for a 20-kg pig or estimated from the results of Hacker et al. (1973) in weaned piglets. It is somewhat lower than that ranging from 10--24 g found in growing--finishing animals (Close, 1980; Bresk and Stolpe, 1979; Fuller and Boyne, 1971; Phillips et al., 1979; Verstegen et al., 1977, 1979). However, expressed in g/kg body weight, the depression amounts from 0.7 to 1.0 g/day per I°C in piglets which is higher than that ranging from 0.23--0.53 g/day per l°C found in growing--finishing animals. Alternatively, the additional amount of food required to sustain similar growth rate in cold as in the optimum temperature is 1.6 g/kg°'TS/day per l°C coldness. This figure compares that of 1.5 g/kg°'TS/day calculated by Close (1980) for a 20-kgpig, but is lower than that ranging from 1.8--2.3 g/kg°'TS/day found in growing--finishing animals (Fuller and Boyne, 1971; Verstegen et al., 1977; Phillips et al., 1979). This, together with the fact that the growth depression (g/kg body weight) is higher in the young pig may be related to the fact that the rate of lean tissue deposition as a proportion of the total tissue deposited i s higher in the young pig than in the older animal (Doornenbal, 1971a, b). The lower efficiency of food utilization expressed as gain/food in cold temperature indicates that a high proportion of food energy is used for maintenance which amounted to 653, 510 and 445 KJ ME/kg°'Ts at the 24--18, 28--22°C and 32--26°C environments, respectively (Noblet and Le Dividich, 1982). Results of Kornegay et al. (1979) suggested that poor performance of piglets during the immediate post-weaning period was due primarily to poor food efficiency. Present results indicate a linear increase in GFR with food intake during the first 2 weeks following weaning. In agreement with the results of Bayley and Carlson (1970) Leibbrandt et al. (1975a) and Kornegay et al. (1974, 1981), this indirectly suggests that poor performance during this period is due mainly to inadequate food intake. The growth depression occurring in piglets maintained below the optimal temperature range is associated with a reduction in P and F of which energy deposited as protein appears to be the less affected in growing--finishing pigs (Fuller and B oyne, 1971; Verstegen et al., 1973; Close et al., 1978; Phillips et al., 1979) and in piglets in the immediate period following weaning (Le

739

Dividich et al., 1980). In the present experiment, P and F expressed in g/day are similarly depressed in cold conditions which also indicates that energy deposited as protein is the less affected on the assumption that the energy content of protein and fat are 23.8 and 39.8 KJ/g, respectively. From eqn. 1 the weight gain reduction associated with the 1.30 g P and 1.35 g F reduction per 1°C coldness may be estimated and amounts to 5.9 and 2.3 g, respectively. This suggests that below thermoneutrality the deposition of lean tissue which represents the major part of the weight gain in weaned piglets is, in absolute, more affected than the fatty tissue deposition. A similar conclusion could be drawn from the results of Fuller and Boyne (1971) and Phillips et al. (1979) which also showed a significant effect of cold temperatures on the reduction in protein gain. Nevertheless, from eqns. 2 and 3 it can be calculated that, irrespective of temperature, piglets begin to gain protein and fat at a daffy food intake higher than 24.5 and 60.5 g/kg °'Ts, respectively. These results, together with those reported previously (Le Dividich et al., 1980) show that protein deposition is prioritary over fat deposition in weaned piglets. Chemical analysis of whole carcass and the measurement of backfat thickness indicate that cold exposure results in leaner carcass in both weaned piglets (Sugahara et al., 1970; Hacker et al., 1973; Brown et al., 1976) and growing--finishing pigs (see the literature in the review by Verstegen et al., 1978). When adjusted to a c o m m o n daily food intake, results of this study also show that cold exposure involves leaner EBWG in piglets although the absolute rate of decrease of P (g/day) and F (g/day) are similar in cold. This is explained by the fact that the relative decrease of F is by 2.3 times higher than that of P. A decrease in b o d y fat content has been reported in piglets during the immediate period following weaning (Le Dividich et al., 1980; Whittemore et al., 1978, 1981), the initial b o d y fat content being recovered in ad libitum feeding conditions by a b o u t 4--6 weeks following weaning (Leibbrandt et al., 1975b; S~ve, 1980a). In the present study the e m p t y b o d y fat content at weaning was 13.3 ± 0.8% and the fat content of the EBWG ranged from 6.6--8.1% which indicates that piglets do not recover their initial b o d y fat content six weeks following weaning. This is related to the fact that the data were adjusted to a c o m m o n food intake of 80 g/kg°'75/day which corresponded to 80--85% of the ad libitum intake. From the regression equations relating fat content of the EBWG to f o o d intake, the level of f o o d intake necessary to recover the initial e m p t y b o d y fat c o n t e n t may be calculated. For example, at 28--22°C it amounts to 102 g/kg °"7S/day.

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740 Bresk, B. and Stolpe, J., 1979. Wechselbeziehungen zwischen Umgebungstemperatur, Leistung und Fiitterungsh~le bei wachsenden Schwein. Arch. Tierernrthr., 29 : 461-467. Brown, D.E., Hacker, R.R. and King, G.J., 1976. Growth and ACTH responses to cold stress of young pigs fed ad libitum. Can. J. Anita. Sci., 56: 365--371. Close, W.H., 1980. The climatic requirements of the pig. In: J.A. Clark (Editor), Environmental aspects of housing for animal production. Butterworths, London, pp. 149--166. Close, W.H., Mount, L.E. and Brown, D., 1978. The effects of plane of nutrition and environmental temperature on the energy metabolism of the growing pig. 2. Growth rate, including protein and fat deposition. Br. J. Nutr., 40: 423--431. Doornenbal, H., 1971a. Growth, development and chemical composition of the pig. I. Lean tissue and protein. Growth, 35: 281--295. Doornenbal, H., 1971b. Growth, development and chemical composition of the pig. II. F a t t y tissue and chemical fat. Growth, 36: 185--194. Fuller, M.F. and Boyne, A.W., 1971. The effects of environmental temperature on the growth and metabolism of pigs given different amounts of food. I. Nitrogen metabolism, growth and body composition. Br. J. Nutr., 25: 259--272. Hacker, R.R., Stefanovic, M.P. and Batra, T.R., 1973. Effects of cold exposure on growing pigs: growth, body composition and 17-ketosteroids. J. Anita. Sci., 37: 739--744. Holmes, C.W. and Close, W.H., 1977. The influence of climatic variables on energy metabolism and associated aspects of productivity in pigs. In: W. Haresign, H. Swan and D. Lewis (Editors), Nutrition and the Climatic Environment. Butterworths, London, pp. 51--73. Kornegay, E.T., Thomas, H.R. and Kramer, C.Y., 1974. Evaluation of protein levels and milk products for pig starter diets. J. Anita. Sci., 39: 527--535. Kornegay, E.T., Ogunbameru, B.O., Collins, E.R., Bryant, K.L., Hinkelmann, K.H. and Knight, J.W., 1979. Double and triple decking of pigs to increase nursery capacity. J. Anita. Sci., 49: 39--43. Kornegay, E.T., Thomas, H.R. and Bryant, K.L., 1981. Flooring materials, pigs per cage and use of oats in starter diets for pigs housed in triple deck nurseries. J. Anita. Sci., 53 : 130--137. Le Dividich, J., 1981. Effects of environmental temperature on the growth rates of early weaned piglets. Livest. Prod. Sci., 8: 75--86. Le Dividich, J., Vermorel, M., Noblet, J., Bouvier, J.C. and Auma~re, A., 1980. Effects of environmental temperature on heat production, energy retention, protein and fat gain in early weaned piglets. Br. J. Nutr., 44: 313--323. Leibbrandt, V.D., Ewan, R.C., Speer, V.C. and Zimmerman, D.R., 1975a. Effect of weaning and age at weaning on baby pig performance. J. Anita. Sci., 40: 1077--1080. Leibbrandt, V.D., Ewan, R.C., Speer, V.C. and Zimmerman, D.R., 1975b. Effect of age and calorie: protein ratio on performance and body composition of baby pigs. J. Anim. Sci., 40: 1081--1085. Mount, L.E., 1973. The concept of thermal neutrality. In: J.L. Monteith and L.E. Mount (Editors), Heat Loss from Animals and Man. Butterworth, pp. 425--439. Nobler, J. and Le Dividich, J., 1982. Effect of environmental temperature and feeding level on energy balance traits of early weaned piglets. Livest. Prod. Sci., 9: 000--000. Phillips, P.A., Young, B.A., Mc Quitty, J.B. and Hardin, R.T., 1979. Effect of low temperature on swine performance. II. Protein deposition, weight gains. Paper no. 794002 presented at the 1979 Summer Meeting of ASAE and CSAE (June 1979). S~ve, B., 1980a. Age at weaning and development of body components of piglets from 3 to 25 kg live weight. Paper presented at the 31st Annual Meeting. E.A.A.P., Miinchen. S~ve, B., 1980b. Le rationnement du porcelet apr~s sevrage: interaction avec l'apport de mati~res azot~es. J. Rech. Porc. Fr., INRA--ITP, Paris, pp. 195--202. Sugahara, M., Baker, D.H., Harmon, B.G. and Jensen, A.H., 1970. Effect of ambient temperature on performance and carcass development in young swine. J. Anim. Sci., 31: 59--62.

741 Verstegen, M.W.A., Close, W.H., Start, I.B. and Mount, L.E., 1973. The effects of environmental temperature and plane of nutrition on heat loss, energy retention and deposition of protein and fat in groups of growing pigs. Br. J. Nutr., 30: 21--35. Verstegen, M.W.A., Van der Hel, W. and Willems, G.E.J.M., 1977. Growth depression and food requirements of fattening pigs at low environmental temperatures when housed either on concrete slats or straw. Anita. Prod., 24: 253--259. Verstegen, M.W.A., Brascamp, E.W. and Van der Hel, W., 1978. Growing and fattening of pigs in relation to temperature and feeding level. Can. J. Anim. Sci., 58: 1--13. Verstegen, M.W.A., Mateman, G., Brandsma, H.A. and Haartsen, P.I., 1979. Rate of gain and carcass quality in fattening pigs at low ambient temperatures. Livest. Prod. Sci., 6: 51--60. Whittemore, C.T., Auma~re, A. and Williams, I.H., 1978. Growth of body components in young weaned pigs. J. Agric. Sci., 91: 681--692. Whittemore, C.T., Taylor, H.M., Henderson, R., Wood, J.D. and Brock, D.C., 1981. Chemical and dissected composition changes in weaned piglets. Anim. Prod., 32: 203--210.

RESUME Le Dividich, J. et Noblet, J., 1982. Croissance et accretion prot~ique et lipidique chez le porcelet seord, ~lev~ en dessous de la thermoneutralit~. Livest. Prod. Sci., 9: 731-742 (en anglals). Deux essais portant sur un effcctif de 78 porcelets sevr~s ~ environ trois semaines d'~ge ont ~t~ entrepris afin de d~terminer l'effet des basses temperatures sur la r~duction la vitesse de croissance, et des d~pSts prot~ique (N × 6,25) (P) et lipidique (F) chez l'animal ~lev~ individuellement. La dur~e de chaque essai est de six semaines. Les milieux climatiques sont 32--26, 28--22 et 24--18°C soit 32, 28 et 24°C au cours de la semaine consecutive au sewage et 26, 22 et 18°C au cours de la derni~re semaine d'exp~rience. Le premier essai comporte les 3 milieux climatiques et un seul niveau alimentaire soit en moycnne 81 g/kg °,Ts par jour sur l'ensemble de l'essai. Le deuxi~me essai comprend deux niveaux alimentaires compl~mentaires et deux traitements climatiques, soit 100 et 74,5 g/kg°,TS/jour en moyenne ~ 24--18°C, 73 et 62 g/kg °,Ts en moyenne ~ 28--22°C. Les d~pSts de prot~ines et de lipides sont estim~s ~ partir de la m~thode des abattages. Les donn~es sont ajust~es ~ u n m~me niveau d'alimentation de 80 g/kg °'Ts/jour. La diminution clu niveau alimentaire de 1 g/kg °' ~S/jour s'accompagne d ' u n e r~duction de 7,67 + 0,72 g/jour de la vitesse de croissance. Cette valeur ne varie pas significativement avec la temperature de l'air. La vitesse de croissance de porcelets et l'efficacit~ alimentaire ajust~es au niveau alimentaire de 80 g/kg °, ~S/jour sont semblables ~ 32--26 et 28--22°C et significativement sup~rieures (P < 0,05) ~ celles obtenues ~ 24--18°C. Une r~duction de 1°C de la temperature de l'air dans l'intervalle 28--22, 24--18°C entrafne une diminution de la vitesse de croissance de 12,2 g/jour. Les d~pSts de prot~ines et de lipides diminuent de 0,98 -+ 0,10 et de 1,24 -+ 0,10 g/ jour pour une r~duction de 1 g/kg °, 7S/jour du niveau alimentaire. Ces coefficients de r~gression ne varient pas significativement avec la temperature de l'air. Une r~duction de la temperature de l'air de 1°C dans l'intervalle 28--22, 24--18°C s'accompagne d'une diminution des d~p~)ts de prot~ines et de lipides de 1,30 et 1,35 g/jour, respectivement. Une r~duction du niveau alimentaire de 1 g/kg °, ~5/jour entrafne une augmentation de la teneur en prot~ines du gain de poids vif vide de 0,09 -+ 0,02% et une diminution de la teneur en lipides de 0,23 + 0,03%. Ces coefficients de regression ne varient pas significativement avec la temperature de Fair.

742

KURZFASSUNG Le Dividich, J. und Noblet, J., 1982. Waehstumsrate sowie Protein- und Fettansatz bei friih-abgesetzten Ferkeln unter thermoneutralen Bedingungen. Livest. Prod. Sci., 9: 731--742 (auf englisch). Nach dem Absetzen mit etwa drei Wochen wurden zwei Versuche mit 78 Ferkeln fiber einen Zeitraum von sechs Wochen durchgefiihrt, um den Einfluss kalter Temperatur auf die Wachstumsdepression sowie den Protein- (N × 6,25) (P) und Fett- (F) Ansatz bei den einzeln aufgestallten Ferkeln zu bestimmen. Die Temperaturwerte und die durchschnitt liche t/igliche Futteraufnahme waren 32--26, 28--22, 24--18°C und 81 g/kg °, 7s (Versuch I); 28--22°C mit 73 und 62 g/kg °, 7~ und 24--18°C mit 100 und 74,5 g/kg °, 75 (Versuch II). Protein- und Fettansatz wurden mit Hilfe einer vergleichenden Schlachttechnik bestimmt. Die Verringerung im Fiitterungsniveau um 1 g/kg °, 7S/Tag war begleitet yon einer Depression der Wachstumsrate um 7,67 + 0,72 g/Tag. Dieser Weft variierte nieht signifikant mit der Lufttemperatur. Bei einer konstanten Futteraufnahme yon 80 g/kg°°7~/Tag waren die Wachstumsrate und die Futterverwertung der Ferkel bei 32--26 und 28--22°C etwa gleieh, w~/hrend diese Werte bei 24--18°C signifikant hSher waren. Die Wachstumsrate sank durchschnittlieh um 12,2 g je l°C Erniedrigung der Temperatur in den Bereichen 28--22 und 24--18°C. Der t~gliche Ansatz an Protein und Fett erhShte sich urn 0,98 -+ 0,10 bzw. 1,24 + 0,10 g/Tag je Einheit Zunahme in der Futteraufnahme. Diese Regressionskoeffizienten variierten nicht signifikant mit der Temperatur. Bei einem konstanten Niveau in der Futteraufnahme verringerte sich der P- und F- Ansantz um 1,30 g bzw. 1,35 g/Tag je 1°C Abfall in der Temperatur bei 28--22°C und 24--18°C. Der Proteinanteil am SchlaehtkSrper bezogen auf die Nettolebendzunahme erhShte sich mit jeder Verringerung in der t~glichen Futteraufnahme um 0,09 + 0,02% und der Fettanteil fie1 entsprechend um 0,23 -+ 0,03%. Diese Regressionskoeffizienten variierten nieht signifikant mit der Temperatur.