No abstract

NRC-suggested levels of Ca and P, and (4) maximization of bone development occurred when pigs were fed 125% P in combination with 125% Ca. (

Three groups of 96 crossbred gilts were weaned at 4 to 5 wk of age (average initial weight, 7.2 kg) and assigned to four dietary treatments in a 2 X 2 factorial arrangement of treatments (ad libitum vs 75% ad libitum and 100 vs 150% of NRC daily Ca and P). The effects of dietary treatments on the gait characteristics of gilts were analyzed by 16-mm motion picture photography. At approximately 50 and 100 kg body weight (periods 1 and 2, respectively), pigs were photographed walking on a treadmill, and gait characteristics were measured from the motion picture film. Ad libitum-fed gilts were longer, taller, wider and deeper when compared with restricted-fed gilts on an equal age basis, but not when compared on an equal weight basis. Other side view and rear view measurements were inconsistently affected by energy level (ad libitum vs restricted) at the two time periods, and all measurements were unaffected by Ca and P level. Analysis of the side and rear view characteristics over time generally revealed undesirable changes (P less than .01) from 59 to 100 kg. Both left and right hock-joint deviation increased (P less than .01) from period 1 to period 2, when expressed on an equal weight basis, suggesting the development of joint weakness. The hind pastern angle and the angle at the hock-joint also increased with time (P less than .01), suggesting development of post-leggedness as pigs increased in age and weight. Correlation coefficients among the various photographic characteristics and structural soundness scores were generally very low. Long-term effects of the dietary treatments on structural development are under study.

Daily gain, daily feed intake, feed per unit of gain, serum Ca, serum P, serum Mg, structural soundness scores, foot pad scores, metacarpal breaking force and metacarpal ash values from five Ca P trials with barrows, gilts or boars were subjected by sex in each trial to multivariate analysis of variance. Correlation coefficients were obtained from the residual sums of squares and sum of products; thus, coefficients were corrected for treatment effects. Individual values were used for all comparisons except those involving daily feed and feed/gain, for which pen means were used. High positive correlations were observed between daily gain and daily feed; there was no relationship between daily gain and feed/gain, but daily feed was positively correlated with feed/gain. Serum Ca levels were not highly correlated with daily gain, daily feed or feed/gain. Although all coefficients were less than .5, serum P was positively (P less than .01 or less than .05) related to daily gain. Serum Ca and serum Mg concentrations were unrelated to serum P concentrations, but serum Ca was positively correlated with serum Mg. There was no relationship between daily gain and soundness or pad scores. Although there were some inconsistencies, a positive relationship was observed between daily gain and metacarpal dried weight, and between daily gain and breaking strength. There appeared to be little, if any, relationship between daily feed and feed/gain and bone parameters. Ca, P and Mg were not consistently related to metacarpal dried weight, breaking strength or ash. Dried weight was positively correlated to breaking strength in four trials and to ash in two trials. Breaking strength was correlated to ash in only one trial. These results offer no support for the belief that stronger, denser bones produce more structurally sound animals, because soundness and pad scores were not related to bone parameters.