Nutritional, physiological, genetic, sex, and age effects on fat-free dry matter composition of the body in avian, fish, and mammalian species: a review.

The purpose of this review is to outline and interpret the effects of nutrition, physiological state, sex, genetics, and age on composition of the fat-free dry matter of birds, mammals, and fishes in order to test the hypothesis that the protein:ash ratio in the body is constant. Calculations from a broad array of published data revealed that nutritional factors, including mineral, protein and amino acid nutriture, frequency and level of feeding, and energy intake and nonnutritional factors, including physiological state, sex, genetic background, and age of animal, may each alter the ratio of protein:ash in the body. All or part of the response may be associated with changes in accretion of body protein and(or) skeletal development and mineralization imposed by these nutritional and nonnutritional factors. In most cases of amino acid or protein deficiency, the protein:ash ratio was decreased relative to the control because the deposition of protein in muscle and viscera was reduced more than the growth and mineralization of the skeleton. In other cases, the protein:ash ratio was increased relative to a control because the dietary Ca or P intake or absorption limited skeletal mineralization. More knowledge is needed of how skeletal development and protein:ash ratio in the body is regulated, especially under the influence of nutritional, ontogenetic, and physiological variables among different genotypes of mammals, birds, and fishes. Documentation that the protein:ash ratio in the whole body of representative mammals, birds, and fishes is not constant, but is subject to manipulation, has important physiological and economic implications for developing food animals for the efficient production of lean meat.

Effects of additional feed during late gestation on reproductive performance of sows: a cooperative study.

A cooperative research study involving 1,080 litters was conducted at eight stations to determine the effects of additional feed during the last 23 d of gestation on reproductive performance of sows and on preweaning performance of their pigs. Primiparous and multiparous sows were fed fortified corn- or sorghum-soybean meal diets (14% crude protein). Control sows received 1.82 kg/d from March through November and 2.27 kg/d from December through February. Treated sows were fed an additional 1.36 kg of feed/d from d 90 of gestation to farrowing. Sows were allowed to consume the same diet ad libitum during a 21-d lactation. Additional feed in late gestation resulted in greater (P less than .001) sow weight gain from d 90 to d 110 of gestation (16.8 vs 9.0 kg) and greater (P less than .001) parturition-lactation weight loss (21.3 vs 16.4 kg). Total weight gain from breeding to 21 d of lactation favored sows that received extra feed (27.5 vs 22.7 kg; P less than .001). Sows receiving extra feed had more live pigs at farrowing (10.05 vs 9.71, P = .06) and at 21 d postpartum (8.35 vs 8.06, P = .09), and the pigs were heavier at birth (1.48 vs 1.44 kg, P = .003) and at 21 d (5.37 vs 5.20 kg, P = .006). Lactation feed intake and number of days from weaning to estrus were not affected by treatment. The results indicate that additional feed in late gestation improves reproductive performance in sows. In this study, the cost of an additional 31 kg of feed/sow was more than offset by the value of the additional sow weight gain (approximately 5 kg), the additional .3 of a pig/litter at weaning and the additional 2.6 kg of total litter weaning weight.

Excess crude protein for nongravid gilts.

Twenty-five nongravid crossbred gilts (avg initial wt, 126 kg) were placed on either a high (38%) or a low (13%) crude protein (CP) diet and fed either at the rate of 1.82 kg/d or had ad libitum access to feed. In addition, a fifth group was pair-fed the 13% CP diet to the average intake of the gilts fed high CP ad libitum. The experimental period lasted 30 d. Corn-soybean meal diets were used and CP levels were varied by altering the corn:soybean meal ratio. Gain and gain/feed were reduced (P less than .01) in gilts fed 1.82 kg/d compared with the gilts fed ad libitum or pair-fed gilts. Gain (P less than .03) and feed intake (P less than .01) of gilts with ad libitum access to the 13% CP diet were higher than those of gilts with ad libitum access to the 38% CP diet. Gain/feed was not different (P greater than .10) between the two groups, however. Rate of gain and feed efficiency of gilts pair-fed the 13% CP diet were similar (P greater than .10) to those of gilts with ad libitum access to the 38% CP diet. Plasma total free amino acids, NH3 and total protein were not (P greater than .10) affected by treatment. Plasma urea-N and urinary total N, urea-N and orotic acid were increased (P less than .01) in gilts fed the high CP diet regardless of feed intake level. However, urinary NH3 was higher (P less than .01) in gilts fed the low-protein diet. These results indicate that excess dietary CP for nongravid gilts decreases gain and feed intake and has no effect on efficiency of feed utilization, but it increases plasma urea-N and urinary total N, urea-N and orotic acid.

Ammonium polyphosphate as a source of phosphorus and nonprotein nitrogen for monogastrics.

Ammonium polyphosphate (APP) was substituted for 0, 50 and 100% of the P supplied by defluorinated rock phosphate (DRP) in corn-soybean meal diets for growing rats and growing-finishing (G-F) pigs. The diets were formulated to contain 10% protein, .75% Ca and .60% P. Two-thirds of the P in the control diet was supplied by DRP. Replacement of 50 or 100% of the DRP with APP increased the dietary N by 7.25 and 14.5%, respectively. To evaluate nonprotein N (NPN) utilization, we used ammonium chloride (NH4Cl) to provide a level of N equivalent to that supplied by APP when it replaced 100% of the P supplied by DRP. These four treatments were repeated with supplementation of limiting amino acids (L-lysine, L-tryptophan and DL-methionine. Daily feed intake, rate of gain and feed:gain (F:G) of rats and G-F pigs were not influenced (P greater than .05) by the substitution of APP for DRP as a P source in corn-soybean meal diets with or without supplemental amino acids. F:G was improved (P less than .05) by the addition of limiting amino acids to diets for pigs, and a similar trend occurred in rats. The addition of NH4Cl to the 10% protein diets as a source of NPN resulted in no observable benefit for growing rats or G-F pigs. Percentages of ham and loin, percentages of bone ash and P content of the bone ash in pigs were not influenced by the dietary treatments.

Use of deuterium oxide for the in vivo prediction of body composition in female rats in various physiological states.

Deuterium oxide (D2O) was used to estimate total body water (TBW) and subsequently to predict the body composition of female rats at breeding, after pregnancy and after lactation as influenced by dietary manipulation. The correlation between D2O space (grams) and body water (grams) was 0.893 (P < 0.01). Deuterium oxide space accounted for 70% of the variance in predicting the weight of TBW. Fixed effects (pregnancy, lactation, feeding levels and two-way interactions) accounted for an additional 10% (P < 0.05) of the variance. The correlation between TBW in grams (predicted from D2O space, grams) and total body protein (grams) was 0.700 (P < 0.01). Total body water accounted for 49% of the variance in total body protein. Fixed effects accounted for an additional 21% (P < 0.05) of the variance in total weight of body protein. The correlations between D2O space (%) and body water (%) and between D20 space (%) and body fat (%) were 0.786 (P < 0.01) and -0.758 (P < 0.01), respectively. The accuracy of estimation of body water (%) and body fat (%) from D2O space was not significantly improved (P > 0.05) when the fixed effects (pregnancy, lactation, feeding levels and two-way interactions) were included in the model.

Effect of energy intake during pregnancy and lactation on body composition in rats.

A paired feeding experiment involving high (H) and low (L) feeding levels during pregnancy and lactation was conducted using bred and open female rats to determine the effects on body composition. Pregnant rats contained a higher percentage of water in the fat-free body (FFB) than that of non-pregnant rats indicating tissue hydration. Composition of the FFB and fat-free dry matter (FFDM) was not altered by feeding level during pregnancy. During lactation, the feeding levels were either continued H-H and L-L or were changed to H-L or L-H within the lactating or open (non-lactating) pairs. Composition of the FFB and of the FFDM was altered by feeding level during lactation. A high energy intake result in a greater proportional loss of ash than of protein during lactation. In contrast, neither the composition of FFB nor FFDM was altered in the non-lactating rats on similar energy intake regimes. The lactating females had a higher percentage of water in FFB than the non-lactating rats. Although there was variation in water content of FFB and in the composition of FFDM, the correlation between percentage of body water and body fat after the adjustment of effects of pregnancy, lactation, energy and their interaction, was high (r = -0.98).

Nutrition and management of early weaned pigs: effect of increased nutrient concentrations and (or) supplemental liquid feeding.

Four experiments involving a total of 304 crossbred pigs weaned at 3 to 4 weeks of age were conducted to examine the effect of feeding supplemental liquid milk two to three times daily at weaning and (or) of altering the nutrient composition of the weaning diet. In addition, the effects on postweaning performance of preconditioning young pigs to supplemental milk feeding in the farrowing house were determined. Performance immediately postweaning was poor and was characterized by low weight gains and low feed intakes for approximately 7 days. Increasing the protein and (or) energy concentrations in the weaning diet had no beneficial effect on pig performance in Exp. 1. Feeding supplemental cow's milk three times daily for 4 days postweaning and (or) adding fat to the dry weaning diet also had no beneficial effect on pig performance in Exp. 2. An added milk product to the diet did tend to improve feed efficiency in this experiment. In the third experiment, performance was not affected by supplemental liquid milk feeding three times daily for 7 days and twice daily for an additional 7 days. Additions of 30% nonfat dried milk to the dry diet offered ad libitum did result in improvement in pig performance. Preconditioning of young pigs to supplemental liquid feeding while still nursing the sow resulted in no beneficial response in pig performance immediately postweaning in Exp. 4.

Ammoniation of corn contaminated with aflatoxin and its effects on growing rats.

Corn naturally contaminated with 2,000 ppb total aflatoxin was adjusted to 17% moisture and ammoniated (Am) with 1.5% (w/w) anhydrous ammonia in an attempt at detoxification. The ammonia treatment reduced the detectable concentration to 510 ppb total aflatoxins. Ninety-six male Sprague-Dawley rats (75 g avg) were randomly divided into eight treatment groups with 12 rats per treatment. A fortified 12%-protein corn-soybean meal diet served as the control (C) diet. The corn used in the C diet contained no detectable aflatoxin. Treatment 2 contained 1,670 ppb aflatoxin; treatments 3 and 4 were similar to treatments 1 and 2, respectively, except the corn used was ammoniated. Treatments 5 through 8 contained 830, 420, 210 and 100 ppb total aflatoxin, respectively. Liver weights expressed as a percentage of final live weight were increased (P less than .05) in rats consuming diets containing 1,670 ppb aflatoxin compared to the other treatments. Serum albumin, IgG and IgM concentrations were not affected by ammoniation or by concentration of aflatoxin in the corn. At the end of 4 weeks, total serum protein was increased (P less than .05) in rats consuming diets containing aflatoxin-contaminated (AfC) corn and Am corn compared to those consuming the C diet. Average daily gain and average daily feed consumption were reduced (P less than .01) in rats consuming the diet containing 1,670 ppb aflatoxin. The growth of rats consuming AfC corn that was Am was equal to that of rats consuming a similar concentration of aflatoxin by dilution. From these results and the results of others, it appears that ammoniation of corn contaminated with aflatoxin may be a practical and economical method for detoxification.