ENERGY VALUE OF SWEET POTATO CHIPS FOR YOUNG SWINE

Transcription

1 ENERGY VALUE OF SWEET POTATO CHIPS FOR YOUNG SWINE J. F. Wu The Pig Researcb Institute, Taiwan, P. O. Box 23 Cbunan, Miaoli, Taiwan, Republic of Cbina Summary A comparative slaughter experiment was conducted to determine the energy values of sweet potato chips for young pigs. Sweet potato chips fed in addition to the basal diet significantly increased daily gain and improved the feed to gain ratio. The apparent digestibility coefficients (ADC) for dry matter and energy remained constant, but the ADC for nitrogen decreased with the addition of sweet potato chips. Digestible energy decreased significantly, while metabolizable energy and net energy remained constant with the addition of sweet potato chips. The average energy values for sweet potato chips, in kilocalories per gram of dry matter, were: gross energy, 4.024; digestible energy, 3.497; metabolizable energy, 3.377, nitrogen-corrected metabolizable energy, 3.332, and net energy, Comparison of the net energy values of corn and sweet potato chips showed that the net energy of sweet potato chips is about 78.8% that of corn. (Key Words: Energy, Sweet Potato Chips, Swine.) Introduction Sweet potatoes (Ipomoea batatas Lain.) are traditionally grown for use as both human and animal food in many tropical and subtropical areas. The sweet potato in the fresh state contains approximately 68% moisture and 32% dry matter (Pond and Maner, 1974). Sweet potatoes have been utilized in many forms in Taiwan as local carbohydrate sources for swine (Koh et al., 1976). They have been fed raw, cooked and as a silage, and they have also been dehydrated to form a meal. Sweet potatoes can be used in swine diets either as a fresh root or as a dehydrated meal. Koh et al. (1976) reported that sweet potato chips properly supplemented with protein are considered an adequate energy source for growing-finishing pigs. The objective of the present experiment was to determine the digestible energy, metabolizable energy and net energy of sun-cured, ground sweet potato chips for young swine. Experimental Procedure A randomized block design experiment was conducted with 16 crossbred pigs (eight males and eight females) averaging 6.5 kg at 35 days of age. Four pigs were assigned to each treatment and treatment groups were randomly assigned to pens in four replications. The basal diet (table 1) was formulated to supply at least twice the requirement for young pigs for all TABLE 1. COMPOSITION OF DIET Internat'l Ingredient Ref. No. % Soybean meal (solv., 44%) Ground yellow corn Soybean oil Defluorinated calcium phosphate Limestone Iodized salt.6 DL-methionine.8 L-lysine.4 ASP-250 a.5 Mecadox- 10 b.5 Vitamin premix c.5 Trace mineral premix d.5 acontributed the following per kilogram of diet: 100 mg chlortetracycline, 100 mg sulfamethazine and 50 mg penicillin. bcontributed the following per kilogram of diet: 50 nag mecadox. CContributed the following per kilogram of diet: 5,400 IU vitamin A, 1,800 IU vitamin D3, 2.9 mg thiamin, 6 nag riboflavin, 3 mg vitamin B6, 14 mg pantothenic acid, 24 mg niacin, 90 mg choline and 48 jag vitamin B t2 9 dcontributed the following per kilogram of diet: 100 mg Zn and 90 mg Fe JOURNAL OF ANIMAL SCIENCE, Vol. 51, No. 6, 1980

2 1262 wu nutrients except energy (NRC, 1979). Therefore, the daily requirements for all nutrients, except energy, were provided in excess if the diet was fed at low levels. The basal diet, which contained 42.8% protcin, was fed to all pigs at 3% of body weight daily during a 7-day adjustment period. After the adjustment, one pig from each replication was slaughtered. The remaining pigs were housed in metabolism cages at a temperature of 26 C. The treatments were sweet potato chips (chemical analysis in tablc 2) fed at (1) O, (2) 1% or (3) 2% of body weight per day plus the basal diet, which was fed at 3% of body weight daily. The daily allotment of feed was supplied in two equal feedings at 0700 and 1800 hr, and feeding levels were adjusted weekly. Each cage was equipped with an automatic nozzle-type waterer, and watcr was given at each feeding. Any feed rcmaining from the previous feeding was collected, pooled for the period, Item TABLE 2. CHEMICAL ANALYSIS OF SWEET POTATO CHIPS, DRY MATTER BASIS a Nitrogen, %.87 Protein, % 5.44 Ether extract, % 1.45 Ash, % 3.89 Crude fiber, % 3.31 Gross energy, kcal/g 3.94 Sweet potato chips asweet potato chips contained 90.44% dry matter. wcighed, dricd at 75 C for 4 days, air equilibrated, ground through a 10-mesh screen and retained for chenaical analysis. After the adjustment period, urine and fecal collections werc poolcd each week for 4 wceks and samples werc "FABLE 3. EFFECT OF SUPPLEMENTAL SWEET POTATO CIIIPS ON PERFORMANCE, DIGESTION AND METABOLISM Item Si 5b Pig performance Daily gain, gcd Feed to gain ratio e Apparent digestion coefficient Dry matter, % Nitrogen, %df Energy, % Nitrogen metabolism Balance, g/daycdg NPU, %cflh BV, %dfi Energy metabolism DE, kcal/g cd ME, kcal/g ME, %DE ~]f NE, kcal/g of body weight. Feeding levels were adjusted weekly. Four pigs were allotted per treatment. bstandard error. Cl.inear effect of level of sweet potato chips (P<.O5). dquadratic effect of level of sweet potato chips (P<.O1). equadratic effect of level of sweet potato chips (P<.05). flinear effect of level of sweet potato chips (P<.01). gnitrogen intake for 28 days minus fecal and urinary nitrogen. hnitrogen balance as a percentage of nitrogen consumed. initrogen balance as a percentage of nitrogen consumed minus fecal nitrogen.

3 SWEET POTATO C]IIPS FOR SWINE 1263 lyophilized for chemical analysis by procedures of De Goey and Ewan (1975a, b). At the end of the experiment, the pigs were killed by electric shock. The intestinal and stomach contents were removed, and the empty, body was stored at -10 C. Frozen empty bodies were ground and lyophilized for chemical analysis as described by l)e Goey and Ewan (1975a). Gross energy of the diets, test ingredients, urine, feces, refused feed and empty body were determined with an adiabatic bomb calorimeter j. Dry matter, ether extract, nitrogen and ash were determined by AOAC (1975) methods. The pig was considered as the experimental unit, and the data were analyzed statistically by the method of least squares (Harvey, 1960). Calculation of Energy Values. Energy values were calculated as described by De Goey and Ewan (1975b), except that the estinaate of the net energy requirement for maintenance was calculated from pooled data for the basal diets used in the experiments of Jimenez (1972), De Goey and Ewan (1975a,b), Phillips and Ewan l Parr Instrument Co., Moline, IL. (1977), Pals and Ewan (1978), Wu and Ewan (1979) and the present experiment. The energy required for maintenance was kcal/dav/ unit of metabolic weight (W vs). Results and Discussion Average daily gain increased linearly (P<.05) and quadratically (P<.01) and the feed to gain ratio improved quadratically (P<.05) as sweet potato chips were added to the basal diet (table 3). The apparent digestion coefficients (AI)C) for dry matter of the diets were not statistically different. The ADC for dietary nitrogen decreased (linearly and quadratically, P<.01), but nitrogen balance increased (linearly, P<.05 and quadratically, P<.O1) with the addition of sweet potato chips. Nitrogen balance, expressed as a percentage of nitrogen intake, increased linearly (P<.05) and quadratically (P<.01) and, expressed as a percentage of nitrogen digested, improved linearly and quadratically (P<.O1) with the addition of sweet potato chips. Nitrogen utilization after digestion improved as additional energy was provided by sweet potato chips, suggesting that more energy was available for the synthesis of new tissue at the high level intake. "FABLE 4. EFFECT OF LEVEL OF SUPPLEMENTAL SWEET POTATO CItlPS ON BODY COMPOSITION OF YOUNG SWINE Item IS b SE e Body composition Dry matter, % Water, % Nitrogen, % Ether extract, % Energy, kcal/g Ash, %d Composition of daily gain Nitrogen, gd Ether extract, gde Energy_ kcald Ash, gf' of body weight. Feeding levels were adjusted weekly. blnitial slaughter group. CStandard error. dquadratic effect of level of sweet potato chips (P<.01). elinear effect of level of sweet potato chips (P<.O1). fquadratic effect of level of sweet potato chips (P<.05).

4 1264 wu TABLE 5. ENERGY VALUES FOR SWEET POTATO CHIPS IN KILOCALOR1ES PER GRAM DRY MATTER Item 1 2 Pooled DE b ME MEn NE of body weight. Feeding levels were adjusted weekly. bmean -+ SE. No difference was observed in the ADC for energy as sweet potato chips were added to the basal diet, but the digestible energy (DE) per gram decreased linearly (P<.05) and quadratically (P<.O1), indicating that the DE per gram of sweet potato chips was less than the DE per gram of the basal diet. Metabolizable energy (ME) values were not significantly affected by the addition of sweet potato chips. ME, expressed as a percentage of DE, increased linearly and quadratically (P<.01) as sweet potato chips were added to the basal diet, from 93.8% to 95.7 and 97.1% for diets 1, 2 and 3, respectively. Dietary crude protein levels decreased from 42.8 to 32.4 and 27.2% when sweet potato chips were added at 1 and 2% of body weight, respectively. The increase in ME as a percentage of DE can be attributed partly to a decrease in crude protein content of the diets. May and Bell (1971) and Morgan et al. (1975) reported that as the level of crude protein decreased in the diet, ME as a percentage of DE increased. Net energy (NE) values of the diets were not significantly affected by the addition of sweet potato chips. No significant differences were observed in the percentages of empty body dry matter, water, nitrogen, ether extract and energy of pigs fed diets containing sweet potato chips (table 4). The percentage of empty body ash decreased quadratically (P<.01). The daily gains in nitrogen (P<.01), energy (P<.01) and ash (P<.05) increased quadratically as sweet potato chips were added to the basal diet. Linear and quadratic (P<.01) increases were observed for ether extract as sweet potato chips were added. The utilization of the energy of sweet potato chips is presented in table 5. The gross energy of sweet potato chips was kcal/g dry matter. Ware (1947) reported that sweet potatoes fed as a fresh root in swine diets had a feeding value 33% that of corn. Lee et al. (1963) showed that dehydrated sweet potato chips had approximately 87% the feeding value of corn when supplemented with soybean cake or a yeast mixed feed. De Goey and Ewan (1975b) reported the NE of corn was keal/g dry matter. In this study, the average NE value of sweet potato chips was kcal/g dry matter. Comparison of the NE values of corn and sweet potato chips shows that the NE of sweet potato chips is about 78.8% that of corn. Literature Cited AOAC Official Methods of Analysis (12th Ed.). Association of Official Analytical Chemists, Washington, DC. De Goey, L. W. and R. C. Ewan. 1975a. Effect of level of intake and diet dilution on energy metabolism in the young pig. J. Anita. Sci. 40:1045. De Goey, L. W. and R. C. Ewan. 1975b. Energy values of corn and oats for young swine. J. Anita. Sci. 40:1052. Harvey, W. R Least-squares analysis of data with unequal subclass members. USDA, ARS Jimenez, J. I Energy utilization by young pigs. M.S. Thesis. Iowa State Univ., Ames. Koh, F. K., T. P. Yeh and H. T. Yen Effects of feeding sweet potatoes, dried sweet potato chips and sweet potato vine on the growth performance of growing-finishing pigs. J. Chinese Soc. Anim. Sci. 5:3. Lee, P. K., Y. F. Yang and S. S. Ling Comparative study on yellow corn grain and sweet potato chips in the nutrition of pigs. Report, Taiwan Provincial Livestock Research Institute, Taiwan, China. May, R. W. and T. M. Bell Digestible and metabolizable energy values of some feeds for the growing pig. Can. J. Anita. Sci. 51:271.

5 SWEET POTATO CHIPS FOR SWINE 1265 Morgan, D. J., D.J.A. Cole and D. Lewi~ Energy values in pig nutrition. I. The relationship between digestible energy, metabolizable energy and total digestible nutrient values of a range of feedstuffs. J. Agt. Sci. (Camb.) 84:7. NRC Nutrient Requirements of Domestic Animals, No. 2. Nutrient Requirements of Swine. Eighth Revised Ed. National Academy of Sciences'National Research Council, Washington, DC. Pals, D. A. and R. C. Ewan utilization of the energy of dried whey and wheat middlings by young swine. J. Anim. Sci. 46:402. Phillips, B. C. and R. C. Ewan Utilization of energy of milo and soybean oil by young swine. J. Anim. Sci. 44:990. Pond, W. G. and J. H. Maner Swine Production in Temperate and Tropical Environment. W. H. Freeman and Co., San Francisco. Ware, L. M Sweet potatoes for livestock. Alabama Agr. Exp. Sta. Progr. Rep. Ser. No. 12. Wu, J. F. and R. C. Ewan Utilization of energy of wheat and barley by young swine. J. Anita. Sci. 49:1470.