Phosphorus in Swine. VI. Utilization of Nitrogen, Calcium and Phosphorus and Reproductive Performance of Gravid Gilts Fed Two Dietary Phosphorus Levels for Five Parities

Abstract

Sixty-two gilts were paired at breeding and assigned randomly to one of the following dietary treatments: (1) low P or (2) high P during gestation and lactation. Two sets of diets (A and B) were formulated; each set to provide a low (10 g) and high (15 g) daily P intake (equal Ca daily intake, 15 g) when fed at 1.82 and 2.27 kg daily, respectively for sets A and B. Females were fed 1.82 kg daily of set A diets during the first 11 wk of gestation, 2.27 kg daily of set B diets for the next 3 wk and 3.34 kg of the appropriate set B diets containing 20% wheat bran until farrowing, at which time the bran was gradually removed from set B diets and the feed level increased to 4 kg daily until weaning. The proportions of defluorinated phosphate and limestone were varied to provide the appropriate level of Ca and P (low and high). At approximately 5 wk before farrowing at each parity, up to 12 females from each group were used in Ca, P and N balance trials that lasted about 2 wk. Dietary P intake did not affect the apparent absorption and retention of N and Ca; 88% of the consumed N was absorbed and one-half of the absorbed was retained, and 37% of the Ca was absorbed and 94% of the absorbed was retained. Females fed the higher P intake, although excreting higher levels of P in the feces and urine, absorbed and retained a larger amount of P; but the low P-fed sows were more efficient in the retention of P when expressed as a percentage of intake or as a percentage of the absorbed P. With the exception of average total litter weight at birth that favored high P-fed sows, live, dead and total pigs at birth, average birth weight and breeding performance were not statistically different between P levels. Except for the first parity, most characteristics favored sows fed the higher P intake. Serum Ca and P levels and hair P concentration were similar between P levels. Hair Ca concentration, however, was higher for the high P-fed sows. Sows fed the higher daily P intake retained more P and there was a trend for better farrowing performance. However, breeding performance, serum Ca and P levels, hair P concentrations and Ca and N balance were similar between dietary P intakes. These results would support current National Research Council-suggested Ca and P levels for sows.

Evaluation of Different Calcium Sources on the Performance of Highly Prolific Lactating Sows

“…The lack of difference on average weight gain of litters and sow milk production between the different levels and sources of Ca is in agreement with the findings of Komegay and Kite and Kornegay et al who evaluated the use of different Ca and P levels for sows and found no differences on litter size, birth weight nor weaning weight [20,21]. Similarly, Maxon and Mahan, studying first and second parity sows for two consecutive reproductive cycles using a Ca to P ratio of 1.3:1, also found no difference in litter parameters [22].…”

Influence of Dietary Calcium-Phosphorus Levels on Apparent Absorption of Minerals and Nitrogen During Growth and Reproduction in Gilts

“…absorption of both Ca and P during the gestation period with higher Ca-P intake was in agreement with the findings of Nimmo et al (1981) and Kornegay and Kite (1983). An overall increase in the absorption of Ca and P during both gestation and lactation from the finishing period could be due to an increased metabolic need of these minerals during these periods.…”

Dietary Calcium and Phosphorus for Lactating Swine at High and Average Production Levels

“…Measures of skeletal strength or bone mineralization are maximized with increasing dietary Ca:P levels for swine from 5 to 110 kg body weight, 3 weeks to 7 months age, (Chapman et al, 1962;Miller et al, 1962;Libal et al, 1969;Fammatre et al, 1977;Mahan et al, 1980;Nlmmo et al, 1981;Mahan, 1982;Maxson and Mahan, 1983)* Peak adult bone mass does not appear necessary for market swine slaughtered between these ages or weights (Miller and Kornegay, 1983)* Peak adult bone mass developed In market swine and selected to remain in the reproducing herd beyond 110 kg body weight or 7 months of age, 13 controversial (Miller and Kornegay, 1983). Several researchers suggest that structural unsoundness or fractures are unrelated to dietary Ca:P levels during growth above HRC (1979) recommended levels (Nlmmo et al, 1980;Kornegay and Thomas, 1981;Arthur et al, 1983;Kornegay and Kite, 1983)* Conversely, other workers (Kornegay et al, 1973;Thomas and Kornegay, 1981;Nlmmo et al, 1981a;Cromwell, 1982;Mahan and Fetter, 1982) lndioate that pigs may benefit from Increased dietary Ca:P above NRC (1979) recommended levels during growth and as an adult in the reproducing herd. Confounded in these results are sex, age, reproductive status as well as feeding practices, differences in experimental conditions and the criteria used to assess results.…”

“…Average weaning weight or the number of pigs weaned has been generally reported unaffected by increasing dietary Ca:P in sows from one to five reproductive cycles (Kornegay et al, 1973;Nimmo et al, 1981a, Hahan andFetter, 1982;Kornegay and Kite, 1983). Therefore, dietary levels of Ca:P, unless they are severely deficient, appear to have little affect on milk production in swine.…”

“…Sows provided with dietary Ca:P levels at or above NRC recommendations (1973 or 1979) have had elevated serum Ca and P levels from one to five parities (Kornegay et al, 1973;Harmon et al, 1974;Hedges et al, 1976;Nimmo et al, 1981a;Mahan and Fetter, 1982;Kornegay and Kite, 1983 In those cases where extreme deficiency causes a mobilization of bone macro-mineral, the minerals released from bone tissue co-exist in the blood stream with those absorbed from the diet. Beoause of the dual origin of Ca, P and Mg, the blood levels of these three minerals do not appear to be a good guide in determining adequaoy of intake, mineral reserves status or to whether reserves are in the prooess of being drawn upon or replenished.…”