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Effect of environmental temperature and dietary energy concentration on the performance and carcass characteristics of growing-finishing pigs fed to equal rate of gain
Livestock Production Science, 17 (1987) 235-246
235
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
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 and D i e t a r y E n e r g y Concentration on the P e r f o r m a n c e and Carcass Characteristics of G r o w i n g - F i n i s h i n g P i g s Fed to Equal Rate of Gain J. LE DIVIDICH, J. NOBLET and T. BIKAWA
Institut National de la Recherche Agronomique, Station de Recherches Porcines, Centre de Rennes-St GiUes, 35590 L 'Hermitage (France) (Accepted 17 March 1987)
ABSTRACT Le Dividich, J., Noblet, J. and Bikawa, T., 1987. Effect of environmental temperature and dietary energy concentration on the performance and carcass characteristics of growing-finishingpigs fed to equal rate of gain. Livest. Prod. Sci., 17: 235-246. An experiment involving 54 individually-housedcastrated male pigs was conducted to determine the interactive effects of environmental temperature (12, 20 or 28°C) and dietary-energy density (13.0 vs. 15.0 MJ digestible energy (DE) kg 1) on the performance and carcass characteristics of growing-finishingpigs, fed to achieve equal rate of weight gain at any treatment. The diets were based either on maize with supplemental maize oil (high-energy diet), or on barley with supplemental wheat bran (low-energy diet). There was no temperature × dietary-energy density interaction (P > 0.10) for any parameter studied. Daily DE intake, and the amount of DE required per unit of body weight gain (BWG) or empty body weight gain (EBWG), increased quadratically (P < 0.01 ) as environmental temperatures decreased. Additional DE required to compensate for 1 °C drop in temperature between 28 and 20°C, and between 20 and 12°C, amounted to 0.20 and 0.44 MJ day -1, respectively. The environmental temperature had no substantial effect on the total fat of the carcass. However, the body fat distribution was modified: backfat weight and thickness were increased (P < 0.05 ) in the cold, whereas weight of leaf fat was decreased (P < 0.05). The decrease in temperature was associated with a linear increase (P < 0.01 ) in the backfat unsaturation rate.
INTRODUCTION
It is generally accepted that the heat increment of feeding contributes to the maintenance of body temperature in the cold-exposed pigs, but has to be dissipated as additional heat under warm conditions (Verstegen et al., 1973 ). The magnitude of the heat increment increases with the amount of feed consumed ( Holmes and Close, 1977), and is inversely related to the energy concentration 0301-6226/87/$03.50
© 1987 Elsevier Science Publishers B.V.
236 of the diet, with fibrous feedstuffs having a higher increment than fat sources (Just, 1982a). It follows that diets possessing a low heat increment would be more beneficial for pigs under warm conditions, while those having a higher heat increment would be better utilized in the cold. In support of this view are the findings of Noblet et al. (1985) that feeding low- or high-energy diets resulted in similar heat production in cold-exposed pigs, whereas within the thermoneutral zone, the low-energy diet was associated with a higher heat production. Data from growth trials indicate that, under ad libitum feeding conditions, high-energy diets increase the rate of gain in the growing-finishing pigs maintained in a warm environment, whereas in the cold low- and high-energy diets result in similar growth rate (Seerley et al., 1978; Stahly and Cromwell, 1979; Coffey et al., 1982; Le Dividich and Noblet, 1986). However, voluntary feed intake and growth rate are known to be influenced both by environmental temperature (Verstegen et al., 1978) and by dietary-energy density (Henry, 1985). It is, therefore, difficult to evaluate the effect of energy density independently of that of the level of feed intake. The present experiment was therefore designed to evaluate the interaction between dietary-energy concentration and environmental temperature on performance and carcass characteristics of growing-finishing pigs, fed to achieve similar growth rate. MATERIALSAND METHODS An experiment involving a total of 54 Large White pigs was conducted to determine the interactive effects of dietary energy level and environmental temperature on the performance of growing-finishing animals, fed to achieve equal rate of gain at 12, 20 and 28 ° C. According to the rearing conditions of the study, the 20 ° C treatment was within the range of the optimum temperature for gain, whereas those of 12 and 28 °C were below the lower critical temperature, and close to the upper limit of the thermoneutral zone of pigs, respectively (Holmes and Close, 1977). The experiment was conducted in 3 similar temperature-controlled rooms (8X8 m), each being equipped with 18 individual pens (1.25X0.65 m) with totally-slatted concrete floors. Air temperature was regulated to within + 0.5 ° C at the level of the pigs. Air moisture was not controlled, but relative humidity (RH) averaged 60 _+3% and 81 _+6% at 28 and 20°C, respectively. At 12 °C, RH was over 95%. Air motion was less than 0.1 m s-1; water was provided ad libitum in each pen from nipple drinkers. The study was designed in a 3 X 2 factorial arrangement, including the 3 ambient temperatures with 2 dietary energy densities at each temperature. One replication (i.e., one block) consisted of 6 castrated male pigs of similar weight and age. A total of 9 replications was used. Before the start of the experiment, the air temperature was set at 20°C in each temperature-controlled
237 room and remained either constant (20°C treatment) or was gradually decreased to 12 ° C or increased to 28 ° C in one week during which the pigs were fed a commercial grower diet. After this 7-day adjustment period, pigs were reweighed and allotted within each room to dietary treatment. At the start of the experiment, pigs averaged 30.8 _+1.1 kg in weight and 74.9 _+4.3 days in age. All pigs of a given replication were slaughtered together when the live weight of 95 kg was reached by at least 4 of them. The actual mean weight at slaughter was 97.3 + 2.9 kg. The two experimental diets were similar to those previously used ( Noblet et al., 1985 ). They were composed of maize, barley, soya-bean meal, wheat bran and maize oil, fortified with minerals and vitamins (Table I). Dietary treatments were: (1) low-energy diet (LE), based on barley with supplemental wheat bran; (2) high-energy diet (HE), based on maize with supplemental maize oil. Digestible energy (DE) and digestible protein (DP) values were taken as those previously determined under thermoneutral conditions (Noblet et al., 1985 ). Diets LE and HE provided 13.01 and 15.02 MJ DE kg- 1, and 136 and 162 g DP kg-1, respectively, so that the ratio of DP/DE was held constant for the 2 diets ( Table I). The feed was offered to the animals in pelleted form, and was given twice daily in similar amount. Feeding levels were adjusted every week according to the metabolic body size (W°75), based on the live weight and on predicted weight gain from weekly weighings. Similar growth rate at any treatment was achieved by changing the amount of daily DE intake according to environmental temperature and energy concentration of the diet. In brief, within each block the amount of DE intake was fixed in the pig on the LE diet at 28 ° C. This amount of DE fed from the start to 50 kg live weight was 1380 KJ DE day- 1 kgO.7~ ( ~ 3.0 × thermoneutral maintenance requirement). Between 50 and 75 kg, this level was gradually reduced to 1210 KJ DE day 1 kg°7~ ( = 2.6 × thermoneutral maintenance requirement), then remained constant until slaughter. The amount of additional DE required to compensate the reduced gain at 20 and 12 °C was estimated from the previous data of Le Dividich et al. (1985). At each temperature a similar amount of DE from either LE or HE diet was offered to the pigs. However, when a variation in daily gain was observed within a block it was taken into account when correcting the amount of DE offered to the pigs during the following week. Following an overnight fast, pigs were electrically stunned and exsanguinated. The digestive tract was removed, weighed and emptied in order to estimate gut contents, empty body weight (EBW) and empty body-weight gain ( EBWG ). The eviscerated carcasses were split into 2 longitudinal halves and chilled for 24 h at + 4 ° C. The left half of each carcass was then cut according to the French procedure described by Ollivier (1970). Weights of fat and of muscle were estimated from the weight of loin, ham, backfat, leaf fat and belly, using the standard methods described by Desmoulin et al. (1976). Percent muscle, fat, backfat and leaf fat were those of the cold left-half carcass minus
238 TABLEI Percentage composition of the diets Diet High energy (HE) Yellow maize, ground Barley, ground Soybean meal, dehulled Maize oil Wheat bran Molasses Dicalcium phosphate Limestone Salt Vitamins and trace minerals, mixture a Analyzed levels (as fed) Crude protein ( % ) Crude fiber ( % ) Neutral detergent fiber ( % ) Acid detergent fiber ( % ) Ether extract ( To) Digestible energy (MJ kg 1) b Digestible protein (g kg 1) b
Low energy (LE)
60.0 28.0 5.0
66.7 18.9
3.0 1.7 1.7 0.5 0.1
7.8 3.0 1.5 1.5 0.4 0.1
18.8 1.9 6.6 2.6 7.9 15.02 162.0
16.7 4.5 13.6 5.5 2.6 13.01 135.6
aContributed per kilogram of diet: Zn, 145 mg; Fe, 50 mg; Cu, 6 mg; Mn, 18 mg; Se, 0.2 mg; I, 0.1 mg; vitamin A, 6 100 IU; vitamin D, 1 220 IU; vitamin E, 12.2 IU; riboflavin, 4.9 mg; pantothenic acid, 12.2 mg; choline, 6.1 mg; vitamin B12, 20/~g; biotin, 240/lg. bValues determined from balance trials (Noblet et al., 1985). head. B a c k f a t t h i c k n e s s was d e t e r m i n e d at t h e last l u m b a r v e r t e b r a . C a r c a s s length was m e a s u r e d f r o m t h e f r o n t of t h e first cervical v e r t e b r a to t h e t u b e r coxae. P o r t i o n s of b a c k f a t a n d l o n g i s s i m u s dorsi m u s c l e ( L - m u s c l e ) , corres p o n d i n g to t h e last rib, were t a k e n on t h e cold h a l f carcass. T h e lipid c o m p o n e n t s of t h e b a c k f a t were e x t r a c t e d b y t h e m e t h o d of F o l c h et al. (1957), a n d m e t h y l e s t e r s p r e p a r e d . F a t t y acids were d e t e r m i n e d b y g a s - l i q u i d c h r o m a t o g r a p h y . T h e L - m u s c l e was a n a l y z e d for m o i s t u r e , c r u d e p r o t e i n a n d e t h e r extract, using standard procedures. D a t a were a n a l y z e d b y p r o c e d u r e s a p p r o p r i a t e for f a c t o r i a l e x p e r i m e n t s ( Snedecor, 1966). RESULTS T h e r e was no e n v i r o n m e n t a l t e m p e r a t u r e × d i e t a r y - e n e r g y d e n s i t y i n t e r a c tion ( P > 0 . 1 0 ) for a n y m e a s u r e d criteria. T h u s , o n l y t h e t e m p e r a t u r e a n d e n e r g y d e n s i t y m a i n effect m e a n s are r e p o r t e d .
239 T A B L E II Effects 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 a n d dietary-energy density on t h e performance of growi n g - f i n i s h i n g pigs Temperature ( m a i n effects )
Diet ( m a i n effects )
12
20
28
HE
LE
B W G ( g day - I ) E B W G (g d a y - ~ ) b
752 e 729 ~
776 e 755 e
774 e 755 e
773 759
761 734
D E intake a n d utilization D E i n t a k e ( M J d a y l)d DE: B W G ( M J k g - 1) c,d DE: E B W G ( M J kg -~ )b,d
35.655 47.38 e 48.98 °
32.27 f 41.65 f 42.79 ~
30.64 g 39.76 ~ 40.77 g
32.70 42.34 43.22
SEM a
13 13
33.00 43.52 45.14
0.29 0.73 0.74
aStandard error of means. bEffect of energy level ( P < 0 . 0 5 ) . CEffect of energy level ( P < 0 . 1 0 ) . dQuadratic effect of t e m p e r a t u r e ( P < 0.01 ). e'f'gTemperature m a i n effect m e a n s in t h e s a m e row with no c o m m o n superscript differ ( P < 0 . 0 5 ) .
As expected, daily body-weight gain ( B W G ) and daily empty body-weight gain ( E B W G ) were not affected ( P > 0.10) by the ambient temperature (Table II ). Feeding the LE diet caused a significant decline ( P < 0.05) in daily E B W G at each of the 3 temperatures. Digestible energy ( D E ) intake, and the amount of DE required per unit of either BWG or EBWG, increased quadratically ( P < 0.01 ) as environmental temperature was lowered from 28 to 12 ° C. Feeding the LE diet increased the amount of DE required per unit of BWG ( P < 0.10) and E B W G ( P < 0.01). The amounts of DE intake, adjusted by covariance to a common BWG of 767 g day -1, were 30.61, 32.23 and 35.72 M J DE day -1 at 28, 20 and 12 ° C, respectively. Similar values were obtained when data were adjusted to a common EBWG. Thus the mean extra DE intake necessary to sustain equal BWG and E B W G at 20 as at 28 ° C, and at 12 as at 20 ° C, amounted to 1.62 and 3.49 M J DE day -~, respectively. Therefore, a mean of 0.20 M J additional DE day-1 was necessary to compensate for a 1 °C decline in temperature between 28 and 20 ° C; between 20 and 12 oC, the corresponding value was 0.44 M J DE day-1. The weight of gut contents as a percentage of live weight, the empty weight of gut as a percentage of E B W and the killing-out percentage were unaffected by environmental temperature {Table III). Reduction of temperature from 28 to 20°C did not influence carcass length, but at 12°C carcasses were shorter ( P < 0.01 ). Feeding LE diet increased ( P < 0.01 ) both the weight of gut contents and the empty-weight of guts. Consequently the killing-out percentage was lowered ( P < 0 . 0 1 ) in pigs receiving LE diet. Expressed as the ratio of weight of hot carcass to EBW, the killing out percentage was less ( P < 0.01) in pigs given LE diet.
240 TABLE III Effects of environmental temperature and dietary-energy density on length of carcass, weight of gut and killing-out percentage Temperature (main effects)
Length (cm) b Gut content ( % live weight)" E m p t y gut ( % empty body weight)" Killing-out percentage Hot carcass (% live weight) (" Hot carcass ( % empty body weight) ¢
Diet (main effects)
12
20
28
HE
LE
100.7 a 3.76 d 5.91 d
103.1 e 3.43 d 5.88 d
102.7 e 3.52 d 5.81 d
102.0 2.98 5.67
102.3 4.16 6.06
81.0 d 84. i d
81.1 d 84.0 d
80.7 d 83.7 d
81.8 84.4
80.0 83.5
SEM a
0.7 0.24 0.13
0.5 0.4
aStand error of means. bQuadratic effect of temperature effect ( P < 0 . 0 5 ) . "Energy density effect ( P < 0 . 0 1 ) . d'°Temperature main effect means in the same row with no common superscript differ ( P < 0.05 ).
Diet had no significant effect ( P < 0.10) on any carcass characteristics (Table IV). There was a tendency ( P < 0 . 1 0 ) for the percentage of muscle to be decreased at the lower temperature (12 ° C ). Ratio of loin to backfat ( kg k g - 1) decreased linearly ( P < 0.05) as the environmental temperature was lowered from 28 to 12 ° C; however only the extreme values were significantly different ( P < 0.05). Backfat thickness and per cent backfat were linearly increased ( P < 0.05) with the decrease in temperature; again only the extreme values were significantly different ( P < 0.05). In contrast, per cent leaf fat was linearly reduced ( P < 0.01 ) with the reduction in temperature. However, per cent fat was not affected ( P > 0.10) by the environmental temperature. Diet had no substantial effect on the L-muscle composition (Table IV); there was only a tendency ( P < 0.10) for the ether extract to be increased in the L-muscle from pigs fed H E diet. There was no significant effect of environmental temperature on the water and ether-extract content in L-muscle. However the protein content increased linearly ( P < 0.01 ) with the decline in temperature. As reflected by the lower ( P < 0.01 ) content in palmitic and stearic acids, and a higher ( P < 0 . 0 1 ) content in linoleic acid, backfat from pigs fed H E diet, based on maize with supplemental maize oil, was more unsaturated ( P < 0.01 ) than that from pigs on LE diet, based on barley with supplemental wheat bran (Table V). Decreasing the environmental temperature was associated with a linear decrease ( P < 0.01 ) in palmitic, stearic and linoleic acids, and a linear increase ( P < 0.01 ) in oleic acid. The degree of backfat unsaturation was linearly increased ( P < 0.01 ) with the decrease in temperature.
241 T A B L E IV Effect of environmental temperature and dietary-energy density on carcass characteristics and c h e m i c a l c o m p o s i t i o n of l o n g i s s i m u s d o r s i m u s c l e ( L - m u s c l e ) Temperature ( m a i n effects)
Diet ( m a i n effects)
SEM ~
12
20
28
HE
LE
Carcass characteristics Muscle ( % ) b Fat (%) Leaf fat (%)¢ Backfat (%)c Backfat (mm) ¢ Loin:Backfat (kg:kg) c
49.5 e 28.8 e 1.37 g 13.6 g 23.6 g 2.27 g
50.9 f 27.8 ~ 1.64 gh 12.5 gh 20.3 gh 2.57 gh
50.0 ef 28.0 ~ 1.96 gh 11.9 h 19.7 h 2.67 h
50.1 28.3 1.70 12.6 21.3 2.51
50.2 28.3 1.61 12.6 21.0 2.51
0.6 0.9 0.14 0.4 1.1 0.14
L-muscle composition Dry matter (%) Protein ( % )c Ether extract ( % ) d
24.9 e 22.8 g 1.09 e
24.9 e 22.3 gh 1.13 ~
24.7 e 22.0 h 1.07 ~
24.9 22.4 1.15
24.8 22.4 1.05
0.2 0.2 0.07
aStandard error of means. bQuadratic effectof temperature (P < 0.I0 ). CLinear effectof temperature (P < 0.01 ). dEflect of energy density (P<0.10). e'fTemperature main effectmeans in the same row with no c o m m o n superscript differ ( P < 0.10). g'hTemperature main effectmeans in the same row with no c o m m o n superscriptdiffer (P < 0.05 ). DISCUSSION
The lower critical temperature (LCT) of individually-housed pigs is in the range of 17-19 ° C during the growing period (Verstegen and Van der Hel, 1974; Close and Mount, 1978). However, in the present study, the quantity of DE required to achieve a similar rate of gain at 20 and at 28 ° C was lower at 28 ° C. This would suggest that the temperature corresponding to minimal heat production does not necessarily coincide with that at which growth performance is optimal. Over the whole experiment a mean extra DE of 0.20 MJ day -1 is required to compensate for 1 ° C drop in temperature between 28 and 20 ° C, and 0.44 MJ day -1 between 20 and 12°C. When expressed in terms of a standard feed containing 13.4 MJ DE kg-1, these values are equivalent to 15 and 33 g of feed, respectively. The finding of an additional feed requirement of 15 g day- 1 per 1 °C decrease between 28 and 20°C is consistent with that of 16 g daythat we reported earlier (Le Dividich et al., 1985). Our estimate of 33 g day -1 extra feed per I°C drop between 20 and 12°C agrees with that of 36 g day -1 derived from growth studies (Le Dividich et al., 1985). Likewise, work by Ver-
242 TABLE V Effects of environmental temperature and dietary-energy density on fatty-acid composition of the back fat" Fatty acids ( % of methyl esters)
16:0 18:0 18:1 18:2 SFA UFA
Temperature (main effects)
Diet (main effects)
12
20
28
HE
LE
20.8 d 11.6 ~t 42.4 d 18.1 d 33.3 d 62.8 ¢~
21.8 d° 13.0" 39.1 a" 18.3 d~ 35.7 e 60.8 a~
22.8 e 14.5 ~ 34.6 e 21.0 ~' 38.5 f 58.0 ~
19.1 10.3 35.7 28.2 30.3 66.0
24.6 15.8 41.7 10.2 41.4 55.1
SEM b
0.4 0.5 0.6 0.7 0.8 0.8
aFor any criteria there was a dietary-energy density effect ( P < 0.01 ) and a linear effect ( P < 0.01 ) of temperature. bStandard error of means. CSFA, sum of saturated fatty acids (%C14:o+% C1~:o+% C~8:o) UFA sum of unsaturated fatty acids (% C16:1+C18:1+% CIS:2+% Cls::J. a'e'rTemperature main effect in the same row with no common superscript differ ( P < 0.05).
stegen et al. (1982) provides a mean value of 33 g day -1 additional feed per 1 °C fall in temperature below LCT. In energy-balance trials, an average value of 35 g day-1 can be estimated from the data of Noblet et al. (1985). In our conditions of equal rate of gain, no interaction was found between environmental temperature and dietary-energy density on DE efficiency. Our data are in contrast with the reported data of Seerley et al. (1978), Stahly and Cromwell (1979), Coffey et al. (1982) and Le Dividich and Noblet (1986), where high-energy diets are found to improve DE efficiency under warm conditions while, in the cold, low- and high-energy diets resulted in similar efficiencies. This suggests that the improved efficiency of HE diets under warm conditions is mainly due to the higher DE intake which is observed with such diets in ad libitum feeding ( Stahly and Cromwell, 1979; Le Dividich and Noblet, 1986). Similarly, metabolic study by Noblet et al. (1985) showed that in conditions of constant ME intake, low- and high-energy diets resulted in similar energy retention in pigs housed in the cold (13 °C), while at 23 °C energy retention was improved with the HE diet. However, the extra energy retained at 23 ° C was deposited as fat, which is therefore associated with a small weight gain. At each temperature, feeding LE diet compared with HE diet was associated with an increase in the weight of the empty gut and particularly of the gut contents, in agreement with the results of Henry (1969) and Just (1982b). This largely accounts for the decreased killing-out percentage which was observed at each temperature in pigs on the LE diet. Therefore, as mentioned
243
by Henry (1985), the increase in weight of the gut and gut contents may lead to an over-estimate of the growth performance and energy efficiency with lowenergy diets compared with high-energy diets. In the present trial, this is illustrated by the fact that feeding LE diet compared with HE diet depressed DE efficiency by 2.8% when expressed as DE/BWG, and by 4.5% when expressed as DE/EBWG. When fed to achieve equal rate of gain, pigs housed at low environmental temperature exhibited a reduction in lean to fat ratio in the body weight gain (Verstegen et al., 1985), suggesting an increased fatness in the cold. Similarly, in the present study, the decrease in temperature was associated with a reduction in the ratio of loin to backfat and an increase in both weight and thickness of backfat. However, no significant effect of temperature was observed on either the percentage of fat in the carcass or the ether extract content in the L-muscle. In fact, the loin-to-backfat ratio accounts only partly for the actual effect of temperature on body composition, since protein content in the L-muscle is increased at low environmental temperature. In addition, our data indicate that the ambient temperature can modify the body-fat partition between subcutaneous and deep-body sites, in that per cent backfat is increased in the cold whereas per cent leaf fat is depressed. This shift of body fat from deep sites to backfat occurring in the cold and the reduced length of carcass (Stahly and Cromwell, 1979; present results) represent adaptations for minimizing heat loss in the cold through an enhanced insulation and a reduced surface exposure, respectively. Fatty acid composition of the backfat is found to be influenced both by diet and by environmental temperature. The fact that linoleic acid content in the backfat was highly increased in pigs fed the diet based on maize with supplemental maize oil, as compared with pigs fed the diet based on barley, reflects the fatty acid composition of maize oil (Brooks, 1971). The increased unsaturation rate of backfat with the decline in ambient temperature is in agreement with the results of Fuller et al. (1974). Interestingly, feeding diets high in maize (and energy ) is less detrimental to the fat consistency when pigs are maintained in warm conditions, whereas feeding diets high in barley ( and lower in energy) can help to counterbalance the effect of cold weather on the softening of fat.
ACKNOWLEDGEMENTS
The authors thank Annick Blanchard, Odile Douillet, Nadine M6zibre, J. Lebost and A. Mounier for technical assistance and J. Gauthier for husbandry of the animals.
244 REFERENCES Brooks, C.E., 1971. Fatty acid composition of pork lipids as affected by diet, fat source and fat level. J. Anim. Sci., 33: 1224-1231. Close, W.H. and Mount, L.E., 1978. The effect of plane of nutrition and environmental temperature on the energy metabolism of the growing pig. 1. Heat loss and critical temperature. Br. J. Nutr., 40: 413-421. Coffey, M.T., Seerley, R.W., Funderburke, D.W. and McCampbell, H.C., 1982. Effect of heat increment and level of dietary energy and environmental temperature on the performance of growing-finishingswine. J. Anim. Sci., 54: 95-105. Desmoulin, B., Grandsart, P. and Tassencourt, L., 1976. Crit~res d'apprdciation de la composition anatomique de la carcasse de porc et des pi~ces de ddcoupe. Principes gdndraux et difficult~s de classification. Journ. Rech. Porcine en France, 8: 89-98. Folch, J., Lees, M. and Standley, G.H.S., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem., 266: 497-509. Fuller, M.F., Duncan, W.R.H. and Boyne, A.W., 1974. Effect of environmental temperature on the degree of unsaturation of depot fats pigs given different amount of food. J. Sci. Fd. Agric., 25: 205-210. Henry, Y., 1969. Effets nutritionnelsde l'incorporation de cellulose purifi~e dans le r~gime du porc en croissance-finition. 2. Influence sur les performances de croissance et la composition corporelle. Ann. Zootech., 23: 171-184. Henry, Y., 1985. Dietary factors involved in feed intake regulation in growing pigs: a review. Livest. Prod. Sci., 12: 339-354. Holmes, C.W. and Close, W.H., 1977. The influence of climatic variables on the energy metabolism and associated aspects of productivity in the pig. In: W. Haresign, H. Swan and D. Lewis (Editors), Nutrition and the Climatic Environment. Butterworths, London, pp. 51-74. Just, A., 1982a. The net energy value of balanced diets for growing pigs. Livest. Prod. Sci., 8: 541-555. Just, A., 1982b. The influence of crude fibre from cereals on the net energy value of diets for growth in pigs. Livest. Prod. Sci., 9: 569-580. Le Dividich, J., Desmoulin, B. and Dourmad, J.Y., 1985. Influence de la temperature ambiante sur les performances du porc en croissance-finition en relation avec le niveau alimentaire. Journ. Rech. Porcine en France, 17: 275-282. Le Dividich, J. and Noblet, J., 1986. Effect of dietary energy level on the performance of individually housed early-weaned piglets in relation to environmentaltemperature. Livest. Prod. Sci., 14: 255-263. Noblet, J., Le Dividich, J. and Bikawa, T., 1985. Interaction between energy level in the diet and environmental temperature on the utilization of energy in growing pigs. J. Anim. Sci., 61: 452-459. Ollivier, L., 1970. L'exp~rience de la descendance chez le porc Large White fran~ais de 1953 h 1966. 1. Analyse de la variation. Ann. G~n~t. Sdl. Anim., 2: 311-324. Seerley, R.W., McDaniel, M.C. and McCampbell, H.C., 1978. Environmental influence on utilization of energy in swine diets. J. Anim. Sci., 47: 427-434. Snedecor, G.W., 1966. Statistical methods, 5th edn. Iowa State University Press, IA, 534 pp. Stahly, T.S. and Cromwell, G.L., 1979. Effect of environmental temperature and dietary fat supplementation on the performance and carcass characteristics of growing and finishing swine. J. Anim. Sci., 49: 1478-1488. 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. and Van der Hel, W., 1974. The effect of temperature and type of floor on the
245 metabolic rate and effective critical temperature in groups of growing pigs. Anim. Prod., 18: 1-11. Verstegen, M.W.A., Brascamp, E.W. and Van der Hel, W., 1978. Growing and fattening of pigs in relation to temperature of housing and feeding level. Can. J. Anim. Sci., 58: 1-13. Verstegen, M.W.A., Brandsma, H.A. and Mateman, G., 1982. Feed requirement of growing pigs at low environmental temperatures. J. Anita. Sci., 55: 88-94. Verstegen, M.W.A., Brandsma, H.A. and Mateman, G., 1985. Effect of ambient temperature and feeding level on slaughter quality in fattening pigs. Neth. J. Agric. Sci., 33: 1-15. RESUME
Le Dividich, J., Noblet, J. et Bikawa, T., 1987. Influence de la concentration dnerg~tique du rdgime sur les performances du porc en croissance-finition rdalisant un gain de poids constant aux temp4ratures ambiantes de 12, 20 et 28°C. Livest. Prod. Sci., 17:235-246 (en anglais). Un essai portant sur un effectif de 54 porcs males castrds pesant initialement 30.8 _ 1.1 kg a dt~ entrepris afin de ddterminer les effets de la concentration dnergdtique du rdgime sur les performances de croissance et la composition corporelle des animaux maintenus aux tempdratures de 28, 20 ou 12 ° C. Deux aliments sont utilisds, l'un dilu4 en 6nergie ( 13.0 MJ EF kg- 1) h base d'orge et de son de bld, l'autre, concentrd en dnergie ( 15.0 MJ ED kg- 1) h base de ma'/s additionnd d'huile de mgfs. Les porcs sont dlev4s individuellementsur sol en caillebotis bdton. Ils sont aliment~s de fa~on telle que les gains de poids journaliers soient comparables aux trois tempdratures. L'interaction entre la tempdrature ambiante et la concentration en dnergie du rdgime n'est significative (P > 0.10) pour aucun des critbres dtudi~s. La quantit~ journalibre d'ED ing~r~e et l'indice de consommation exprim6 en MJ ED kg- 1 de gain de poids vif ou kg- 1 de gain de poids vif vide augmentent de mani~re quadratique (P < 0.01 ) lorsque la tempdrature ambiante diminue de 28 h 12 ° C. La quantitd d'ED ndcessaire pour compenser l'effet de rabaissement de la tempdrature ambiante de 1 °C entre 28 et 20 °C sur le gain de poids s'dl~ve h 0.20 MJ jour-1; entre 20 et 12 ° C, la valeur correspondante est de 0.44 MJ jour- 1. La tempdrature ambiante n'a pas d'effet notable sur la masse adipeuse totale de la carcasse, mais elle modifie sa rdpartition: le pourcentage de gras externe (bardi~re) augmente (P < 0.01 ) avec rabaissement de la tempdrature ambiante tandis que |e pourcentage de gras interne (panne) diminue (P < 0.01 ). Le degr~ d'insaturation du gras externe augmente (P < 0.01 ) avec la diminution de la temperature ambiante. KURZFASSUNG Le Dividich, J., Noblet, J. und Bikawa, T., 1987. Einflu£ von Umgebungstemperatur und Energiekonzentration im Futter auf Mast- und Schlachtleistung von Mastschweinen bei gleichem Tageszuwachs. Livest. Prod. Sci., 17:233-246 (auf englisch). Das Experiment wurde mit 54 kastrierten miinnlichen Schweinen in Einzelhaltung durchgefiihrt. Es sollten Wechselwirkungen zwischen der Umgebungstemperatur (12, 20 und 28 °C) und der Energiedichte im Futter ( 13.0 und 15.0 MJ verdauliche Energie (DE) kg 1in ihrem Einflu~ auf Mast- und Schlachtleistungskriterienbei schlachtfertigen Mastschweinen untersucht werden. Dabei wurden die Tiere so versorgt, da£ ftir jede Behandlung gleiche Tageszunahmen erreicht werden konnten. Die Futterrationen bestanden zum einen hauptsiichlich aus Mais und zusiitzlich MaisS1 (hohe Energiedichte), zum anderen aus Gerste mit Zusatz von Weizenkleie (niedrige Energiedichte). Bei kienem der untersuchten Parameter konnte eine signifikante Wechselwirkung ( P > 0.10) zwischen Temperatur und Futterenergiekonzentrationgefunden werden. Sowohl die t~gliche Aufnahme an DE als auch der Verbrauch an DE pro Einheit Lebendgewichtszunahme bzw. Netto-
246 zunahme erhShte sich quadratisch ( P < 0.01) bei sinkender Umgebungstemperatur. Zum Ausgleich mui~ten zwischen 28 und 20°C pro 1 °C Temperaturrtickgang 0.20 MJ DE und zwischen 20 und 12 °C 0.44 MJ DE pro Tier und Tag zus~itzlich verabreicht werden. Die Umgebungstemperatur hatte keine nennenswerten Auswirkungen auf den Fettanteil im SchlachtkSrper. Lediglich die Verteilung des KSrperfettes war ver~indert: bei kiihler Temperatur waren Riickenspeckdicke und Rtickenspeckmasse erhSht ( P < 0.05), w~ihrend das KSrperh~hlenfett gewichtsm~ii~ig abnahm (P < 0.05). Der Temperaturrtickgang war mit einem linearen Anstieg des S~ttigungsgrades im Riickenspeck verbunden {P<0.01 ).
235
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
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 and D i e t a r y E n e r g y Concentration on the P e r f o r m a n c e and Carcass Characteristics of G r o w i n g - F i n i s h i n g P i g s Fed to Equal Rate of Gain J. LE DIVIDICH, J. NOBLET and T. BIKAWA
Institut National de la Recherche Agronomique, Station de Recherches Porcines, Centre de Rennes-St GiUes, 35590 L 'Hermitage (France) (Accepted 17 March 1987)
ABSTRACT Le Dividich, J., Noblet, J. and Bikawa, T., 1987. Effect of environmental temperature and dietary energy concentration on the performance and carcass characteristics of growing-finishingpigs fed to equal rate of gain. Livest. Prod. Sci., 17: 235-246. An experiment involving 54 individually-housedcastrated male pigs was conducted to determine the interactive effects of environmental temperature (12, 20 or 28°C) and dietary-energy density (13.0 vs. 15.0 MJ digestible energy (DE) kg 1) on the performance and carcass characteristics of growing-finishingpigs, fed to achieve equal rate of weight gain at any treatment. The diets were based either on maize with supplemental maize oil (high-energy diet), or on barley with supplemental wheat bran (low-energy diet). There was no temperature × dietary-energy density interaction (P > 0.10) for any parameter studied. Daily DE intake, and the amount of DE required per unit of body weight gain (BWG) or empty body weight gain (EBWG), increased quadratically (P < 0.01 ) as environmental temperatures decreased. Additional DE required to compensate for 1 °C drop in temperature between 28 and 20°C, and between 20 and 12°C, amounted to 0.20 and 0.44 MJ day -1, respectively. The environmental temperature had no substantial effect on the total fat of the carcass. However, the body fat distribution was modified: backfat weight and thickness were increased (P < 0.05 ) in the cold, whereas weight of leaf fat was decreased (P < 0.05). The decrease in temperature was associated with a linear increase (P < 0.01 ) in the backfat unsaturation rate.
INTRODUCTION
It is generally accepted that the heat increment of feeding contributes to the maintenance of body temperature in the cold-exposed pigs, but has to be dissipated as additional heat under warm conditions (Verstegen et al., 1973 ). The magnitude of the heat increment increases with the amount of feed consumed ( Holmes and Close, 1977), and is inversely related to the energy concentration 0301-6226/87/$03.50
© 1987 Elsevier Science Publishers B.V.
236 of the diet, with fibrous feedstuffs having a higher increment than fat sources (Just, 1982a). It follows that diets possessing a low heat increment would be more beneficial for pigs under warm conditions, while those having a higher heat increment would be better utilized in the cold. In support of this view are the findings of Noblet et al. (1985) that feeding low- or high-energy diets resulted in similar heat production in cold-exposed pigs, whereas within the thermoneutral zone, the low-energy diet was associated with a higher heat production. Data from growth trials indicate that, under ad libitum feeding conditions, high-energy diets increase the rate of gain in the growing-finishing pigs maintained in a warm environment, whereas in the cold low- and high-energy diets result in similar growth rate (Seerley et al., 1978; Stahly and Cromwell, 1979; Coffey et al., 1982; Le Dividich and Noblet, 1986). However, voluntary feed intake and growth rate are known to be influenced both by environmental temperature (Verstegen et al., 1978) and by dietary-energy density (Henry, 1985). It is, therefore, difficult to evaluate the effect of energy density independently of that of the level of feed intake. The present experiment was therefore designed to evaluate the interaction between dietary-energy concentration and environmental temperature on performance and carcass characteristics of growing-finishing pigs, fed to achieve similar growth rate. MATERIALSAND METHODS An experiment involving a total of 54 Large White pigs was conducted to determine the interactive effects of dietary energy level and environmental temperature on the performance of growing-finishing animals, fed to achieve equal rate of gain at 12, 20 and 28 ° C. According to the rearing conditions of the study, the 20 ° C treatment was within the range of the optimum temperature for gain, whereas those of 12 and 28 °C were below the lower critical temperature, and close to the upper limit of the thermoneutral zone of pigs, respectively (Holmes and Close, 1977). The experiment was conducted in 3 similar temperature-controlled rooms (8X8 m), each being equipped with 18 individual pens (1.25X0.65 m) with totally-slatted concrete floors. Air temperature was regulated to within + 0.5 ° C at the level of the pigs. Air moisture was not controlled, but relative humidity (RH) averaged 60 _+3% and 81 _+6% at 28 and 20°C, respectively. At 12 °C, RH was over 95%. Air motion was less than 0.1 m s-1; water was provided ad libitum in each pen from nipple drinkers. The study was designed in a 3 X 2 factorial arrangement, including the 3 ambient temperatures with 2 dietary energy densities at each temperature. One replication (i.e., one block) consisted of 6 castrated male pigs of similar weight and age. A total of 9 replications was used. Before the start of the experiment, the air temperature was set at 20°C in each temperature-controlled
237 room and remained either constant (20°C treatment) or was gradually decreased to 12 ° C or increased to 28 ° C in one week during which the pigs were fed a commercial grower diet. After this 7-day adjustment period, pigs were reweighed and allotted within each room to dietary treatment. At the start of the experiment, pigs averaged 30.8 _+1.1 kg in weight and 74.9 _+4.3 days in age. All pigs of a given replication were slaughtered together when the live weight of 95 kg was reached by at least 4 of them. The actual mean weight at slaughter was 97.3 + 2.9 kg. The two experimental diets were similar to those previously used ( Noblet et al., 1985 ). They were composed of maize, barley, soya-bean meal, wheat bran and maize oil, fortified with minerals and vitamins (Table I). Dietary treatments were: (1) low-energy diet (LE), based on barley with supplemental wheat bran; (2) high-energy diet (HE), based on maize with supplemental maize oil. Digestible energy (DE) and digestible protein (DP) values were taken as those previously determined under thermoneutral conditions (Noblet et al., 1985 ). Diets LE and HE provided 13.01 and 15.02 MJ DE kg- 1, and 136 and 162 g DP kg-1, respectively, so that the ratio of DP/DE was held constant for the 2 diets ( Table I). The feed was offered to the animals in pelleted form, and was given twice daily in similar amount. Feeding levels were adjusted every week according to the metabolic body size (W°75), based on the live weight and on predicted weight gain from weekly weighings. Similar growth rate at any treatment was achieved by changing the amount of daily DE intake according to environmental temperature and energy concentration of the diet. In brief, within each block the amount of DE intake was fixed in the pig on the LE diet at 28 ° C. This amount of DE fed from the start to 50 kg live weight was 1380 KJ DE day- 1 kgO.7~ ( ~ 3.0 × thermoneutral maintenance requirement). Between 50 and 75 kg, this level was gradually reduced to 1210 KJ DE day 1 kg°7~ ( = 2.6 × thermoneutral maintenance requirement), then remained constant until slaughter. The amount of additional DE required to compensate the reduced gain at 20 and 12 °C was estimated from the previous data of Le Dividich et al. (1985). At each temperature a similar amount of DE from either LE or HE diet was offered to the pigs. However, when a variation in daily gain was observed within a block it was taken into account when correcting the amount of DE offered to the pigs during the following week. Following an overnight fast, pigs were electrically stunned and exsanguinated. The digestive tract was removed, weighed and emptied in order to estimate gut contents, empty body weight (EBW) and empty body-weight gain ( EBWG ). The eviscerated carcasses were split into 2 longitudinal halves and chilled for 24 h at + 4 ° C. The left half of each carcass was then cut according to the French procedure described by Ollivier (1970). Weights of fat and of muscle were estimated from the weight of loin, ham, backfat, leaf fat and belly, using the standard methods described by Desmoulin et al. (1976). Percent muscle, fat, backfat and leaf fat were those of the cold left-half carcass minus
238 TABLEI Percentage composition of the diets Diet High energy (HE) Yellow maize, ground Barley, ground Soybean meal, dehulled Maize oil Wheat bran Molasses Dicalcium phosphate Limestone Salt Vitamins and trace minerals, mixture a Analyzed levels (as fed) Crude protein ( % ) Crude fiber ( % ) Neutral detergent fiber ( % ) Acid detergent fiber ( % ) Ether extract ( To) Digestible energy (MJ kg 1) b Digestible protein (g kg 1) b
Low energy (LE)
60.0 28.0 5.0
66.7 18.9
3.0 1.7 1.7 0.5 0.1
7.8 3.0 1.5 1.5 0.4 0.1
18.8 1.9 6.6 2.6 7.9 15.02 162.0
16.7 4.5 13.6 5.5 2.6 13.01 135.6
aContributed per kilogram of diet: Zn, 145 mg; Fe, 50 mg; Cu, 6 mg; Mn, 18 mg; Se, 0.2 mg; I, 0.1 mg; vitamin A, 6 100 IU; vitamin D, 1 220 IU; vitamin E, 12.2 IU; riboflavin, 4.9 mg; pantothenic acid, 12.2 mg; choline, 6.1 mg; vitamin B12, 20/~g; biotin, 240/lg. bValues determined from balance trials (Noblet et al., 1985). head. B a c k f a t t h i c k n e s s was d e t e r m i n e d at t h e last l u m b a r v e r t e b r a . C a r c a s s length was m e a s u r e d f r o m t h e f r o n t of t h e first cervical v e r t e b r a to t h e t u b e r coxae. P o r t i o n s of b a c k f a t a n d l o n g i s s i m u s dorsi m u s c l e ( L - m u s c l e ) , corres p o n d i n g to t h e last rib, were t a k e n on t h e cold h a l f carcass. T h e lipid c o m p o n e n t s of t h e b a c k f a t were e x t r a c t e d b y t h e m e t h o d of F o l c h et al. (1957), a n d m e t h y l e s t e r s p r e p a r e d . F a t t y acids were d e t e r m i n e d b y g a s - l i q u i d c h r o m a t o g r a p h y . T h e L - m u s c l e was a n a l y z e d for m o i s t u r e , c r u d e p r o t e i n a n d e t h e r extract, using standard procedures. D a t a were a n a l y z e d b y p r o c e d u r e s a p p r o p r i a t e for f a c t o r i a l e x p e r i m e n t s ( Snedecor, 1966). RESULTS T h e r e was no e n v i r o n m e n t a l t e m p e r a t u r e × d i e t a r y - e n e r g y d e n s i t y i n t e r a c tion ( P > 0 . 1 0 ) for a n y m e a s u r e d criteria. T h u s , o n l y t h e t e m p e r a t u r e a n d e n e r g y d e n s i t y m a i n effect m e a n s are r e p o r t e d .
239 T A B L E II Effects 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 a n d dietary-energy density on t h e performance of growi n g - f i n i s h i n g pigs Temperature ( m a i n effects )
Diet ( m a i n effects )
12
20
28
HE
LE
B W G ( g day - I ) E B W G (g d a y - ~ ) b
752 e 729 ~
776 e 755 e
774 e 755 e
773 759
761 734
D E intake a n d utilization D E i n t a k e ( M J d a y l)d DE: B W G ( M J k g - 1) c,d DE: E B W G ( M J kg -~ )b,d
35.655 47.38 e 48.98 °
32.27 f 41.65 f 42.79 ~
30.64 g 39.76 ~ 40.77 g
32.70 42.34 43.22
SEM a
13 13
33.00 43.52 45.14
0.29 0.73 0.74
aStandard error of means. bEffect of energy level ( P < 0 . 0 5 ) . CEffect of energy level ( P < 0 . 1 0 ) . dQuadratic effect of t e m p e r a t u r e ( P < 0.01 ). e'f'gTemperature m a i n effect m e a n s in t h e s a m e row with no c o m m o n superscript differ ( P < 0 . 0 5 ) .
As expected, daily body-weight gain ( B W G ) and daily empty body-weight gain ( E B W G ) were not affected ( P > 0.10) by the ambient temperature (Table II ). Feeding the LE diet caused a significant decline ( P < 0.05) in daily E B W G at each of the 3 temperatures. Digestible energy ( D E ) intake, and the amount of DE required per unit of either BWG or EBWG, increased quadratically ( P < 0.01 ) as environmental temperature was lowered from 28 to 12 ° C. Feeding the LE diet increased the amount of DE required per unit of BWG ( P < 0.10) and E B W G ( P < 0.01). The amounts of DE intake, adjusted by covariance to a common BWG of 767 g day -1, were 30.61, 32.23 and 35.72 M J DE day -1 at 28, 20 and 12 ° C, respectively. Similar values were obtained when data were adjusted to a common EBWG. Thus the mean extra DE intake necessary to sustain equal BWG and E B W G at 20 as at 28 ° C, and at 12 as at 20 ° C, amounted to 1.62 and 3.49 M J DE day -~, respectively. Therefore, a mean of 0.20 M J additional DE day-1 was necessary to compensate for a 1 °C decline in temperature between 28 and 20 ° C; between 20 and 12 oC, the corresponding value was 0.44 M J DE day-1. The weight of gut contents as a percentage of live weight, the empty weight of gut as a percentage of E B W and the killing-out percentage were unaffected by environmental temperature {Table III). Reduction of temperature from 28 to 20°C did not influence carcass length, but at 12°C carcasses were shorter ( P < 0.01 ). Feeding LE diet increased ( P < 0.01 ) both the weight of gut contents and the empty-weight of guts. Consequently the killing-out percentage was lowered ( P < 0 . 0 1 ) in pigs receiving LE diet. Expressed as the ratio of weight of hot carcass to EBW, the killing out percentage was less ( P < 0.01) in pigs given LE diet.
240 TABLE III Effects of environmental temperature and dietary-energy density on length of carcass, weight of gut and killing-out percentage Temperature (main effects)
Length (cm) b Gut content ( % live weight)" E m p t y gut ( % empty body weight)" Killing-out percentage Hot carcass (% live weight) (" Hot carcass ( % empty body weight) ¢
Diet (main effects)
12
20
28
HE
LE
100.7 a 3.76 d 5.91 d
103.1 e 3.43 d 5.88 d
102.7 e 3.52 d 5.81 d
102.0 2.98 5.67
102.3 4.16 6.06
81.0 d 84. i d
81.1 d 84.0 d
80.7 d 83.7 d
81.8 84.4
80.0 83.5
SEM a
0.7 0.24 0.13
0.5 0.4
aStand error of means. bQuadratic effect of temperature effect ( P < 0 . 0 5 ) . "Energy density effect ( P < 0 . 0 1 ) . d'°Temperature main effect means in the same row with no common superscript differ ( P < 0.05 ).
Diet had no significant effect ( P < 0.10) on any carcass characteristics (Table IV). There was a tendency ( P < 0 . 1 0 ) for the percentage of muscle to be decreased at the lower temperature (12 ° C ). Ratio of loin to backfat ( kg k g - 1) decreased linearly ( P < 0.05) as the environmental temperature was lowered from 28 to 12 ° C; however only the extreme values were significantly different ( P < 0.05). Backfat thickness and per cent backfat were linearly increased ( P < 0.05) with the decrease in temperature; again only the extreme values were significantly different ( P < 0.05). In contrast, per cent leaf fat was linearly reduced ( P < 0.01 ) with the reduction in temperature. However, per cent fat was not affected ( P > 0.10) by the environmental temperature. Diet had no substantial effect on the L-muscle composition (Table IV); there was only a tendency ( P < 0.10) for the ether extract to be increased in the L-muscle from pigs fed H E diet. There was no significant effect of environmental temperature on the water and ether-extract content in L-muscle. However the protein content increased linearly ( P < 0.01 ) with the decline in temperature. As reflected by the lower ( P < 0.01 ) content in palmitic and stearic acids, and a higher ( P < 0 . 0 1 ) content in linoleic acid, backfat from pigs fed H E diet, based on maize with supplemental maize oil, was more unsaturated ( P < 0.01 ) than that from pigs on LE diet, based on barley with supplemental wheat bran (Table V). Decreasing the environmental temperature was associated with a linear decrease ( P < 0.01 ) in palmitic, stearic and linoleic acids, and a linear increase ( P < 0.01 ) in oleic acid. The degree of backfat unsaturation was linearly increased ( P < 0.01 ) with the decrease in temperature.
241 T A B L E IV Effect of environmental temperature and dietary-energy density on carcass characteristics and c h e m i c a l c o m p o s i t i o n of l o n g i s s i m u s d o r s i m u s c l e ( L - m u s c l e ) Temperature ( m a i n effects)
Diet ( m a i n effects)
SEM ~
12
20
28
HE
LE
Carcass characteristics Muscle ( % ) b Fat (%) Leaf fat (%)¢ Backfat (%)c Backfat (mm) ¢ Loin:Backfat (kg:kg) c
49.5 e 28.8 e 1.37 g 13.6 g 23.6 g 2.27 g
50.9 f 27.8 ~ 1.64 gh 12.5 gh 20.3 gh 2.57 gh
50.0 ef 28.0 ~ 1.96 gh 11.9 h 19.7 h 2.67 h
50.1 28.3 1.70 12.6 21.3 2.51
50.2 28.3 1.61 12.6 21.0 2.51
0.6 0.9 0.14 0.4 1.1 0.14
L-muscle composition Dry matter (%) Protein ( % )c Ether extract ( % ) d
24.9 e 22.8 g 1.09 e
24.9 e 22.3 gh 1.13 ~
24.7 e 22.0 h 1.07 ~
24.9 22.4 1.15
24.8 22.4 1.05
0.2 0.2 0.07
aStandard error of means. bQuadratic effectof temperature (P < 0.I0 ). CLinear effectof temperature (P < 0.01 ). dEflect of energy density (P<0.10). e'fTemperature main effectmeans in the same row with no c o m m o n superscript differ ( P < 0.10). g'hTemperature main effectmeans in the same row with no c o m m o n superscriptdiffer (P < 0.05 ). DISCUSSION
The lower critical temperature (LCT) of individually-housed pigs is in the range of 17-19 ° C during the growing period (Verstegen and Van der Hel, 1974; Close and Mount, 1978). However, in the present study, the quantity of DE required to achieve a similar rate of gain at 20 and at 28 ° C was lower at 28 ° C. This would suggest that the temperature corresponding to minimal heat production does not necessarily coincide with that at which growth performance is optimal. Over the whole experiment a mean extra DE of 0.20 MJ day -1 is required to compensate for 1 ° C drop in temperature between 28 and 20 ° C, and 0.44 MJ day -1 between 20 and 12°C. When expressed in terms of a standard feed containing 13.4 MJ DE kg-1, these values are equivalent to 15 and 33 g of feed, respectively. The finding of an additional feed requirement of 15 g day- 1 per 1 °C decrease between 28 and 20°C is consistent with that of 16 g daythat we reported earlier (Le Dividich et al., 1985). Our estimate of 33 g day -1 extra feed per I°C drop between 20 and 12°C agrees with that of 36 g day -1 derived from growth studies (Le Dividich et al., 1985). Likewise, work by Ver-
242 TABLE V Effects of environmental temperature and dietary-energy density on fatty-acid composition of the back fat" Fatty acids ( % of methyl esters)
16:0 18:0 18:1 18:2 SFA UFA
Temperature (main effects)
Diet (main effects)
12
20
28
HE
LE
20.8 d 11.6 ~t 42.4 d 18.1 d 33.3 d 62.8 ¢~
21.8 d° 13.0" 39.1 a" 18.3 d~ 35.7 e 60.8 a~
22.8 e 14.5 ~ 34.6 e 21.0 ~' 38.5 f 58.0 ~
19.1 10.3 35.7 28.2 30.3 66.0
24.6 15.8 41.7 10.2 41.4 55.1
SEM b
0.4 0.5 0.6 0.7 0.8 0.8
aFor any criteria there was a dietary-energy density effect ( P < 0.01 ) and a linear effect ( P < 0.01 ) of temperature. bStandard error of means. CSFA, sum of saturated fatty acids (%C14:o+% C1~:o+% C~8:o) UFA sum of unsaturated fatty acids (% C16:1+C18:1+% CIS:2+% Cls::J. a'e'rTemperature main effect in the same row with no common superscript differ ( P < 0.05).
stegen et al. (1982) provides a mean value of 33 g day -1 additional feed per 1 °C fall in temperature below LCT. In energy-balance trials, an average value of 35 g day-1 can be estimated from the data of Noblet et al. (1985). In our conditions of equal rate of gain, no interaction was found between environmental temperature and dietary-energy density on DE efficiency. Our data are in contrast with the reported data of Seerley et al. (1978), Stahly and Cromwell (1979), Coffey et al. (1982) and Le Dividich and Noblet (1986), where high-energy diets are found to improve DE efficiency under warm conditions while, in the cold, low- and high-energy diets resulted in similar efficiencies. This suggests that the improved efficiency of HE diets under warm conditions is mainly due to the higher DE intake which is observed with such diets in ad libitum feeding ( Stahly and Cromwell, 1979; Le Dividich and Noblet, 1986). Similarly, metabolic study by Noblet et al. (1985) showed that in conditions of constant ME intake, low- and high-energy diets resulted in similar energy retention in pigs housed in the cold (13 °C), while at 23 °C energy retention was improved with the HE diet. However, the extra energy retained at 23 ° C was deposited as fat, which is therefore associated with a small weight gain. At each temperature, feeding LE diet compared with HE diet was associated with an increase in the weight of the empty gut and particularly of the gut contents, in agreement with the results of Henry (1969) and Just (1982b). This largely accounts for the decreased killing-out percentage which was observed at each temperature in pigs on the LE diet. Therefore, as mentioned
243
by Henry (1985), the increase in weight of the gut and gut contents may lead to an over-estimate of the growth performance and energy efficiency with lowenergy diets compared with high-energy diets. In the present trial, this is illustrated by the fact that feeding LE diet compared with HE diet depressed DE efficiency by 2.8% when expressed as DE/BWG, and by 4.5% when expressed as DE/EBWG. When fed to achieve equal rate of gain, pigs housed at low environmental temperature exhibited a reduction in lean to fat ratio in the body weight gain (Verstegen et al., 1985), suggesting an increased fatness in the cold. Similarly, in the present study, the decrease in temperature was associated with a reduction in the ratio of loin to backfat and an increase in both weight and thickness of backfat. However, no significant effect of temperature was observed on either the percentage of fat in the carcass or the ether extract content in the L-muscle. In fact, the loin-to-backfat ratio accounts only partly for the actual effect of temperature on body composition, since protein content in the L-muscle is increased at low environmental temperature. In addition, our data indicate that the ambient temperature can modify the body-fat partition between subcutaneous and deep-body sites, in that per cent backfat is increased in the cold whereas per cent leaf fat is depressed. This shift of body fat from deep sites to backfat occurring in the cold and the reduced length of carcass (Stahly and Cromwell, 1979; present results) represent adaptations for minimizing heat loss in the cold through an enhanced insulation and a reduced surface exposure, respectively. Fatty acid composition of the backfat is found to be influenced both by diet and by environmental temperature. The fact that linoleic acid content in the backfat was highly increased in pigs fed the diet based on maize with supplemental maize oil, as compared with pigs fed the diet based on barley, reflects the fatty acid composition of maize oil (Brooks, 1971). The increased unsaturation rate of backfat with the decline in ambient temperature is in agreement with the results of Fuller et al. (1974). Interestingly, feeding diets high in maize (and energy ) is less detrimental to the fat consistency when pigs are maintained in warm conditions, whereas feeding diets high in barley ( and lower in energy) can help to counterbalance the effect of cold weather on the softening of fat.
ACKNOWLEDGEMENTS
The authors thank Annick Blanchard, Odile Douillet, Nadine M6zibre, J. Lebost and A. Mounier for technical assistance and J. Gauthier for husbandry of the animals.
244 REFERENCES Brooks, C.E., 1971. Fatty acid composition of pork lipids as affected by diet, fat source and fat level. J. Anim. Sci., 33: 1224-1231. Close, W.H. and Mount, L.E., 1978. The effect of plane of nutrition and environmental temperature on the energy metabolism of the growing pig. 1. Heat loss and critical temperature. Br. J. Nutr., 40: 413-421. Coffey, M.T., Seerley, R.W., Funderburke, D.W. and McCampbell, H.C., 1982. Effect of heat increment and level of dietary energy and environmental temperature on the performance of growing-finishingswine. J. Anim. Sci., 54: 95-105. Desmoulin, B., Grandsart, P. and Tassencourt, L., 1976. Crit~res d'apprdciation de la composition anatomique de la carcasse de porc et des pi~ces de ddcoupe. Principes gdndraux et difficult~s de classification. Journ. Rech. Porcine en France, 8: 89-98. Folch, J., Lees, M. and Standley, G.H.S., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem., 266: 497-509. Fuller, M.F., Duncan, W.R.H. and Boyne, A.W., 1974. Effect of environmental temperature on the degree of unsaturation of depot fats pigs given different amount of food. J. Sci. Fd. Agric., 25: 205-210. Henry, Y., 1969. Effets nutritionnelsde l'incorporation de cellulose purifi~e dans le r~gime du porc en croissance-finition. 2. Influence sur les performances de croissance et la composition corporelle. Ann. Zootech., 23: 171-184. Henry, Y., 1985. Dietary factors involved in feed intake regulation in growing pigs: a review. Livest. Prod. Sci., 12: 339-354. Holmes, C.W. and Close, W.H., 1977. The influence of climatic variables on the energy metabolism and associated aspects of productivity in the pig. In: W. Haresign, H. Swan and D. Lewis (Editors), Nutrition and the Climatic Environment. Butterworths, London, pp. 51-74. Just, A., 1982a. The net energy value of balanced diets for growing pigs. Livest. Prod. Sci., 8: 541-555. Just, A., 1982b. The influence of crude fibre from cereals on the net energy value of diets for growth in pigs. Livest. Prod. Sci., 9: 569-580. Le Dividich, J., Desmoulin, B. and Dourmad, J.Y., 1985. Influence de la temperature ambiante sur les performances du porc en croissance-finition en relation avec le niveau alimentaire. Journ. Rech. Porcine en France, 17: 275-282. Le Dividich, J. and Noblet, J., 1986. Effect of dietary energy level on the performance of individually housed early-weaned piglets in relation to environmentaltemperature. Livest. Prod. Sci., 14: 255-263. Noblet, J., Le Dividich, J. and Bikawa, T., 1985. Interaction between energy level in the diet and environmental temperature on the utilization of energy in growing pigs. J. Anim. Sci., 61: 452-459. Ollivier, L., 1970. L'exp~rience de la descendance chez le porc Large White fran~ais de 1953 h 1966. 1. Analyse de la variation. Ann. G~n~t. Sdl. Anim., 2: 311-324. Seerley, R.W., McDaniel, M.C. and McCampbell, H.C., 1978. Environmental influence on utilization of energy in swine diets. J. Anim. Sci., 47: 427-434. Snedecor, G.W., 1966. Statistical methods, 5th edn. Iowa State University Press, IA, 534 pp. Stahly, T.S. and Cromwell, G.L., 1979. Effect of environmental temperature and dietary fat supplementation on the performance and carcass characteristics of growing and finishing swine. J. Anim. Sci., 49: 1478-1488. 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. and Van der Hel, W., 1974. The effect of temperature and type of floor on the
245 metabolic rate and effective critical temperature in groups of growing pigs. Anim. Prod., 18: 1-11. Verstegen, M.W.A., Brascamp, E.W. and Van der Hel, W., 1978. Growing and fattening of pigs in relation to temperature of housing and feeding level. Can. J. Anim. Sci., 58: 1-13. Verstegen, M.W.A., Brandsma, H.A. and Mateman, G., 1982. Feed requirement of growing pigs at low environmental temperatures. J. Anita. Sci., 55: 88-94. Verstegen, M.W.A., Brandsma, H.A. and Mateman, G., 1985. Effect of ambient temperature and feeding level on slaughter quality in fattening pigs. Neth. J. Agric. Sci., 33: 1-15. RESUME
Le Dividich, J., Noblet, J. et Bikawa, T., 1987. Influence de la concentration dnerg~tique du rdgime sur les performances du porc en croissance-finition rdalisant un gain de poids constant aux temp4ratures ambiantes de 12, 20 et 28°C. Livest. Prod. Sci., 17:235-246 (en anglais). Un essai portant sur un effectif de 54 porcs males castrds pesant initialement 30.8 _ 1.1 kg a dt~ entrepris afin de ddterminer les effets de la concentration dnergdtique du rdgime sur les performances de croissance et la composition corporelle des animaux maintenus aux tempdratures de 28, 20 ou 12 ° C. Deux aliments sont utilisds, l'un dilu4 en 6nergie ( 13.0 MJ EF kg- 1) h base d'orge et de son de bld, l'autre, concentrd en dnergie ( 15.0 MJ ED kg- 1) h base de ma'/s additionnd d'huile de mgfs. Les porcs sont dlev4s individuellementsur sol en caillebotis bdton. Ils sont aliment~s de fa~on telle que les gains de poids journaliers soient comparables aux trois tempdratures. L'interaction entre la tempdrature ambiante et la concentration en dnergie du rdgime n'est significative (P > 0.10) pour aucun des critbres dtudi~s. La quantit~ journalibre d'ED ing~r~e et l'indice de consommation exprim6 en MJ ED kg- 1 de gain de poids vif ou kg- 1 de gain de poids vif vide augmentent de mani~re quadratique (P < 0.01 ) lorsque la tempdrature ambiante diminue de 28 h 12 ° C. La quantitd d'ED ndcessaire pour compenser l'effet de rabaissement de la tempdrature ambiante de 1 °C entre 28 et 20 °C sur le gain de poids s'dl~ve h 0.20 MJ jour-1; entre 20 et 12 ° C, la valeur correspondante est de 0.44 MJ jour- 1. La tempdrature ambiante n'a pas d'effet notable sur la masse adipeuse totale de la carcasse, mais elle modifie sa rdpartition: le pourcentage de gras externe (bardi~re) augmente (P < 0.01 ) avec rabaissement de la tempdrature ambiante tandis que |e pourcentage de gras interne (panne) diminue (P < 0.01 ). Le degr~ d'insaturation du gras externe augmente (P < 0.01 ) avec la diminution de la temperature ambiante. KURZFASSUNG Le Dividich, J., Noblet, J. und Bikawa, T., 1987. Einflu£ von Umgebungstemperatur und Energiekonzentration im Futter auf Mast- und Schlachtleistung von Mastschweinen bei gleichem Tageszuwachs. Livest. Prod. Sci., 17:233-246 (auf englisch). Das Experiment wurde mit 54 kastrierten miinnlichen Schweinen in Einzelhaltung durchgefiihrt. Es sollten Wechselwirkungen zwischen der Umgebungstemperatur (12, 20 und 28 °C) und der Energiedichte im Futter ( 13.0 und 15.0 MJ verdauliche Energie (DE) kg 1in ihrem Einflu~ auf Mast- und Schlachtleistungskriterienbei schlachtfertigen Mastschweinen untersucht werden. Dabei wurden die Tiere so versorgt, da£ ftir jede Behandlung gleiche Tageszunahmen erreicht werden konnten. Die Futterrationen bestanden zum einen hauptsiichlich aus Mais und zusiitzlich MaisS1 (hohe Energiedichte), zum anderen aus Gerste mit Zusatz von Weizenkleie (niedrige Energiedichte). Bei kienem der untersuchten Parameter konnte eine signifikante Wechselwirkung ( P > 0.10) zwischen Temperatur und Futterenergiekonzentrationgefunden werden. Sowohl die t~gliche Aufnahme an DE als auch der Verbrauch an DE pro Einheit Lebendgewichtszunahme bzw. Netto-
246 zunahme erhShte sich quadratisch ( P < 0.01) bei sinkender Umgebungstemperatur. Zum Ausgleich mui~ten zwischen 28 und 20°C pro 1 °C Temperaturrtickgang 0.20 MJ DE und zwischen 20 und 12 °C 0.44 MJ DE pro Tier und Tag zus~itzlich verabreicht werden. Die Umgebungstemperatur hatte keine nennenswerten Auswirkungen auf den Fettanteil im SchlachtkSrper. Lediglich die Verteilung des KSrperfettes war ver~indert: bei kiihler Temperatur waren Riickenspeckdicke und Rtickenspeckmasse erhSht ( P < 0.05), w~ihrend das KSrperh~hlenfett gewichtsm~ii~ig abnahm (P < 0.05). Der Temperaturrtickgang war mit einem linearen Anstieg des S~ttigungsgrades im Riickenspeck verbunden {P<0.01 ).