INFLUENCE OF WEANING ON SWINE ADIPOSE TISSUE LIPOLYSIS H. J. Mersmann, G. Phinney and L. J. Brown 1
SUMMARY
INTRODUCTION
Weaning of swine f r o m a milk diet to a grain diet (lower fat and protein) yielded a decrease in the epinephrine-stimulated maximal lipolytic rate as well as t h e sensitivity to epinephrine in adipose tissue slices. The dietary influence was n o t solely the caloric or fat c o n t e n t of the diet since a similar lard-fortified diet with caloric and fat c o n t e n t similar to the milk yielded maximal lipolytic rates and epinephrine sensitivities that were intermediate b e t w e e n the milk diet and the grain diet. (Key Words: Lipolysis, Epinephrine, Swine, Weaning, Diet.)
The lipolytic activity o f adipose tissue slices obtained f r o m 45-day-old swine was stimulated by several catecholamines (Mersmann et al., 1974). The responsiveness of the tissue to epinephrine (Epi) decreased as the animals increased in age f r o m 25 days postpartum, i.e., the maximal lipolytic rate decreased and the c o n c e n t r a t i o n of the h o r m o n e needed to achieve the m a x i m u m increased (Mersmann et al.; 1975). Since the 25-day animals were u n w e a n e d and older animals weaned, the observed decrease in lipolytic activity and sensitivity to Epi could be the result of any or all of the following: the dietary change at weaning, the physiological stress of weaning, the increased chronological age, or the increased size of the pigs. The present experiments were designed to test the effect of weaning on the lipolytic response.
~We would like to thank Dr. D. E. DeKay for the diet analysis arid Mr. F. Gonsalves for the animal care. 2Mailing Address: Shell Development Company, Biological Sciences Research Center, P. O. Box 4248, Modesto, California 95325. 3 Soweena| is a sow milk replacer manufactured by MATERIALS AND METHODS Foremost Foods Company, San Francisco, California. It contains dried skimmed milk, partially demineralFive crossbred sows (Yorkshire, Hampshire, ized whey, vegetable oil preserved with BHT, sodium Duroc) were farrowed and the pigs allowed to caseinate, lecithin, and vitamin and mineral supplesuckle for 5 days after which the sow was ments. The manufacturer will not reveal the percent of removed f r o m the pen and the pigs were fed a the various components. The manufacturer's guaranteed analysis is: crude protein, not less than 25.0%; milk replacer (Soweena| 3 ad libitum f r o m crude fat, not less than 10.0%; crude fiber (none); open pans (80 g S o w e e n a | p o w d e r plus 500 ml lactose, not less than 50.0%; neomycin (base) 200g/ of water). F r o m 12 to 19 days p o s t p a r t u m the ton; Vitamin A, not less than 25,000 USP units/lb; pigs also had access to dry p o w d e r e d milk Vitamin D~, not less than 2,500 USP units/lb; Vitamin E, not less than 50 IU units/lb; and riboflavin, not less (Soweena| in feeders. At 19 days P o s t p a r t u m than 24 mg/lb. Our analysis was 25% protein, 10% fat, each litter (balancing sex and weight) was and 4.5 kcal energy per kilogram. distributed (three pigs per diet f r o m each litter) 4The commercial starter ration contained 68% into three d i e t a r y groups: liquid plus dry corn, 1% milo, 21% soybean meal (49% protein), 6% p o w d e r e d milk (M) ; a commercial starter ration dehydrated alfalfa meal (20% protein), 2.5% whey and vitamin, mineral, and methionine supplements. The of low fat c o n t e n t (LF) 4 ; and the same ration calculated analysis was 17.9% crude protein, 2.7% supplemented with 10% lard (HF). The HF and crude fat, 3.3% fiber, 4.6% ash, .4% methionine, .5% LF diets were offered in open pans as a phosphorous, .6% calcium, 1.4% linoleic acid, 22.1 thoroughly m o i s t e n e d gruel and in dry f o r m in mg/kg xanthophyll, 6.9 mg/kg riboflavin, 20.5 mg/kg pantothen, 38.7 mg/kg niacin, 1128. mg/kg choline, feeders; all diets and water were offered ad 26,100 IU/kg Vitamin A, and 4,700 IU/kg Vitamin libitum. All animals fed a given diet were D 3, Our analyzsis was 17% protein, 3% fat, and 3.9 kcal energy per kilogram, wheras this diet supple- group-fed in a c o m m o n pen and, consequently, no feed intake was measured. mented with 10% lard yielded 16% protein, 11% fat, A f t e r a b o u t 2 weeks on the diets (32 to 36 and 4.4 kcal energy per kilogram. 1048 JOURNAL OF ANIMAL SCIENCE, Vol. 41, No. 4, 1975
Downloaded from https://academic.oup.com/jas/article-abstract/41/4/1048/4668144 by Iowa State University user on 24 January 2019
Shell Development Company, Biological Sciences Researcb Center 2, Modesto 95352
WEANING AND LIPOLYSIS
1049
logrithmic transformation were statistically analyzed by a two-way analysis of variance considering the factors, litter and diet.
8 7 /k =LF
6
~ , / ~
RESULTS
..K"/
4
3
2
I
0
I0
Age
20 (days)
I ~0
40
Figure 1. Weight gain. Weight in kg is indicated as mean +- SE. The dietary groups indicated are: milk (M), weaned at day 19 to a corn-soy diet low in fat (LF), and weaned at day 19 to a diet similar to LF but supplemented with 10% lard (HF). days postpartum), the three pigs from each litter, on each diet, were sacrificed by a cephalic blow coupled with exsanguination. Backfat was removed and sliced, and an equally weighted, pooled sample of slices from the three littermates on the respective diet was obtained. The slices (200 mg) were incubated for 2 hr with shaking at 37 ~ under 95% 02 to 5% CO2 in a Krebs-Ringer-bicarbonate type buffer fortified with glucose, albumin treated to remove fatty acids, ascorbate, and the appropriate concentration of Epi (as indicated in figure 2). At the termination of incubation, the medium was analyzed for fatty acids (FA) using a titration method and glycerol (Glyc) using an enzymatic method. Details of the methodology and optimization of the incubation system for swine tissue were previously described (Mersmann et al., 1974). For each set of responses to Epi by the pooled tissue from littermates, a probit by log dose-response curve was estimated using least squares for the FA and Glyc release data. This resulted in estimates of the basal (no exogenous hormone) and maximal lipolytic rates of response and the EDs0 (dose of Epi required to achieve 50% of the maximal response) of the response. (In contrast to the estimates of descriptive parameters for each dose-response curve, figure 2 comprises a composite doseresponse curve with SE for the entire study.) For each variable discussed, the data after a
The average weight of the pigs in the three dietary groups is indicated in figure 1. The weight gains at day 29 compared to day 19 were M > LF = HF (P LF > HF (P LF) is a reflection of the inability of young pigs to effectively utilize many types of dietary fat (Frobish et al., 1969, 1970). Log dose-response curves composited across all litters for the three diets as measured by the release of FA are indicated in figure 2. The Glyc release data, although not presented, were similar. Composite dose-response curves may be misleading since animal variation in maximal response and EDs0 can bias the shape and position of the curves. As expected, analysis of individual dose-response curves indicated significant litter effects in regard to the maximal response as measured by FA release. There
80
O =HF ~ = LF
60
I~ "'''"" .......... ."
~//.-
,o
.~.';
~ ' ~
03
I I
I 3 Epi (pM)
I 9
I 27
I 81
Figure 2. Composite log dose-response curves. The response of pooled adipose tissue slices obtained from three littermates on a given diet to various doses of Epi as a percent of the maximal lipolytic response is indicated. For each diet five litters are represented. The data are indicated as the mean -+ SE and the dietary groups are as indicated in figure 1.
Downloaded from https://academic.oup.com/jas/article-abstract/41/4/1048/4668144 by Iowa State University user on 24 January 2019
"'S;
5
1050
MERSMANN, PHINNEY AND BROWN TABLE 1. CHARACTERISTICS OF THE EPI DOSE-RESPONSE CURVE
Characteristicb Basal response c
Maximal response c
EDs 0 c
na
FA
Glyc
FA
Glyc
FA
Glyc
Milk Low fat High fat
5 5 5
.21 .32 .23
.27 .28 .40
7.1 d 4.8 e 5.1 e
2.4 2.1 2.2
.89 d 3.27 e 1.69 d
.68 d 1.97 e 1.61 de
an = number of litters: three animals from each litter were distributed to each diet; the lipolytic data were obtained using a pooled sample of tissue obtained from the three animals (one litter fed the milk diet represents only two animals). bThe data are detransformed least square means. Values in a column with different superscripts (d,e) are significantly different (P
SUMMARY
INTRODUCTION
Weaning of swine f r o m a milk diet to a grain diet (lower fat and protein) yielded a decrease in the epinephrine-stimulated maximal lipolytic rate as well as t h e sensitivity to epinephrine in adipose tissue slices. The dietary influence was n o t solely the caloric or fat c o n t e n t of the diet since a similar lard-fortified diet with caloric and fat c o n t e n t similar to the milk yielded maximal lipolytic rates and epinephrine sensitivities that were intermediate b e t w e e n the milk diet and the grain diet. (Key Words: Lipolysis, Epinephrine, Swine, Weaning, Diet.)
The lipolytic activity o f adipose tissue slices obtained f r o m 45-day-old swine was stimulated by several catecholamines (Mersmann et al., 1974). The responsiveness of the tissue to epinephrine (Epi) decreased as the animals increased in age f r o m 25 days postpartum, i.e., the maximal lipolytic rate decreased and the c o n c e n t r a t i o n of the h o r m o n e needed to achieve the m a x i m u m increased (Mersmann et al.; 1975). Since the 25-day animals were u n w e a n e d and older animals weaned, the observed decrease in lipolytic activity and sensitivity to Epi could be the result of any or all of the following: the dietary change at weaning, the physiological stress of weaning, the increased chronological age, or the increased size of the pigs. The present experiments were designed to test the effect of weaning on the lipolytic response.
~We would like to thank Dr. D. E. DeKay for the diet analysis arid Mr. F. Gonsalves for the animal care. 2Mailing Address: Shell Development Company, Biological Sciences Research Center, P. O. Box 4248, Modesto, California 95325. 3 Soweena| is a sow milk replacer manufactured by MATERIALS AND METHODS Foremost Foods Company, San Francisco, California. It contains dried skimmed milk, partially demineralFive crossbred sows (Yorkshire, Hampshire, ized whey, vegetable oil preserved with BHT, sodium Duroc) were farrowed and the pigs allowed to caseinate, lecithin, and vitamin and mineral supplesuckle for 5 days after which the sow was ments. The manufacturer will not reveal the percent of removed f r o m the pen and the pigs were fed a the various components. The manufacturer's guaranteed analysis is: crude protein, not less than 25.0%; milk replacer (Soweena| 3 ad libitum f r o m crude fat, not less than 10.0%; crude fiber (none); open pans (80 g S o w e e n a | p o w d e r plus 500 ml lactose, not less than 50.0%; neomycin (base) 200g/ of water). F r o m 12 to 19 days p o s t p a r t u m the ton; Vitamin A, not less than 25,000 USP units/lb; pigs also had access to dry p o w d e r e d milk Vitamin D~, not less than 2,500 USP units/lb; Vitamin E, not less than 50 IU units/lb; and riboflavin, not less (Soweena| in feeders. At 19 days P o s t p a r t u m than 24 mg/lb. Our analysis was 25% protein, 10% fat, each litter (balancing sex and weight) was and 4.5 kcal energy per kilogram. distributed (three pigs per diet f r o m each litter) 4The commercial starter ration contained 68% into three d i e t a r y groups: liquid plus dry corn, 1% milo, 21% soybean meal (49% protein), 6% p o w d e r e d milk (M) ; a commercial starter ration dehydrated alfalfa meal (20% protein), 2.5% whey and vitamin, mineral, and methionine supplements. The of low fat c o n t e n t (LF) 4 ; and the same ration calculated analysis was 17.9% crude protein, 2.7% supplemented with 10% lard (HF). The HF and crude fat, 3.3% fiber, 4.6% ash, .4% methionine, .5% LF diets were offered in open pans as a phosphorous, .6% calcium, 1.4% linoleic acid, 22.1 thoroughly m o i s t e n e d gruel and in dry f o r m in mg/kg xanthophyll, 6.9 mg/kg riboflavin, 20.5 mg/kg pantothen, 38.7 mg/kg niacin, 1128. mg/kg choline, feeders; all diets and water were offered ad 26,100 IU/kg Vitamin A, and 4,700 IU/kg Vitamin libitum. All animals fed a given diet were D 3, Our analyzsis was 17% protein, 3% fat, and 3.9 kcal energy per kilogram, wheras this diet supple- group-fed in a c o m m o n pen and, consequently, no feed intake was measured. mented with 10% lard yielded 16% protein, 11% fat, A f t e r a b o u t 2 weeks on the diets (32 to 36 and 4.4 kcal energy per kilogram. 1048 JOURNAL OF ANIMAL SCIENCE, Vol. 41, No. 4, 1975
Downloaded from https://academic.oup.com/jas/article-abstract/41/4/1048/4668144 by Iowa State University user on 24 January 2019
Shell Development Company, Biological Sciences Researcb Center 2, Modesto 95352
WEANING AND LIPOLYSIS
1049
logrithmic transformation were statistically analyzed by a two-way analysis of variance considering the factors, litter and diet.
8 7 /k =LF
6
~ , / ~
RESULTS
..K"/
4
3
2
I
0
I0
Age
20 (days)
I ~0
40
Figure 1. Weight gain. Weight in kg is indicated as mean +- SE. The dietary groups indicated are: milk (M), weaned at day 19 to a corn-soy diet low in fat (LF), and weaned at day 19 to a diet similar to LF but supplemented with 10% lard (HF). days postpartum), the three pigs from each litter, on each diet, were sacrificed by a cephalic blow coupled with exsanguination. Backfat was removed and sliced, and an equally weighted, pooled sample of slices from the three littermates on the respective diet was obtained. The slices (200 mg) were incubated for 2 hr with shaking at 37 ~ under 95% 02 to 5% CO2 in a Krebs-Ringer-bicarbonate type buffer fortified with glucose, albumin treated to remove fatty acids, ascorbate, and the appropriate concentration of Epi (as indicated in figure 2). At the termination of incubation, the medium was analyzed for fatty acids (FA) using a titration method and glycerol (Glyc) using an enzymatic method. Details of the methodology and optimization of the incubation system for swine tissue were previously described (Mersmann et al., 1974). For each set of responses to Epi by the pooled tissue from littermates, a probit by log dose-response curve was estimated using least squares for the FA and Glyc release data. This resulted in estimates of the basal (no exogenous hormone) and maximal lipolytic rates of response and the EDs0 (dose of Epi required to achieve 50% of the maximal response) of the response. (In contrast to the estimates of descriptive parameters for each dose-response curve, figure 2 comprises a composite doseresponse curve with SE for the entire study.) For each variable discussed, the data after a
The average weight of the pigs in the three dietary groups is indicated in figure 1. The weight gains at day 29 compared to day 19 were M > LF = HF (P LF > HF (P LF) is a reflection of the inability of young pigs to effectively utilize many types of dietary fat (Frobish et al., 1969, 1970). Log dose-response curves composited across all litters for the three diets as measured by the release of FA are indicated in figure 2. The Glyc release data, although not presented, were similar. Composite dose-response curves may be misleading since animal variation in maximal response and EDs0 can bias the shape and position of the curves. As expected, analysis of individual dose-response curves indicated significant litter effects in regard to the maximal response as measured by FA release. There
80
O =HF ~ = LF
60
I~ "'''"" .......... ."
~//.-
,o
.~.';
~ ' ~
03
I I
I 3 Epi (pM)
I 9
I 27
I 81
Figure 2. Composite log dose-response curves. The response of pooled adipose tissue slices obtained from three littermates on a given diet to various doses of Epi as a percent of the maximal lipolytic response is indicated. For each diet five litters are represented. The data are indicated as the mean -+ SE and the dietary groups are as indicated in figure 1.
Downloaded from https://academic.oup.com/jas/article-abstract/41/4/1048/4668144 by Iowa State University user on 24 January 2019
"'S;
5
1050
MERSMANN, PHINNEY AND BROWN TABLE 1. CHARACTERISTICS OF THE EPI DOSE-RESPONSE CURVE
Characteristicb Basal response c
Maximal response c
EDs 0 c
na
FA
Glyc
FA
Glyc
FA
Glyc
Milk Low fat High fat
5 5 5
.21 .32 .23
.27 .28 .40
7.1 d 4.8 e 5.1 e
2.4 2.1 2.2
.89 d 3.27 e 1.69 d
.68 d 1.97 e 1.61 de
an = number of litters: three animals from each litter were distributed to each diet; the lipolytic data were obtained using a pooled sample of tissue obtained from the three animals (one litter fed the milk diet represents only two animals). bThe data are detransformed least square means. Values in a column with different superscripts (d,e) are significantly different (P
