Restricted energy intake and elevated calcium and phosphorus intake for gilts during growth. II. Gait characteristics analyzed from 16-mm motion picture photography

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.