The following aspects of protein growth in pigs were examined:
I. Shape of daily protein and lean deposition rate against age and
live weight. 45 Large White pigs were fed to appetite; littermate trios
were serially slaughtered between 55 and 330 days of age. Daily feed
intakes increased linearly until 140 days and 85 kg LW. Daily protein
and lean gains, 55-195 days and 20-150 kg, were 0.128, 0.255 (boars),
0.108, 0.221 (g ilts ), 0.117, 0.234 (castrates). Dissected lean was
2.21 total body protein. Estimated MEm value, 0.545 MJME per kg
W⁰⁷⁵ d⁻¹; kp was 0.27 and kl, 0.73.
II. Body composition after weaning. Weight stasis concealed substantial
lipid loss from carcass fatty tissue and continued growth of carcass
muscle plus bone. Recovery from post-weaning growth check was more
rapid when diets of high nutrient density were offered. Thirty-five
female pigs were given 4 intake treatments and serially slaughtered
between 25 and 70 days. During refeeding previously-restricted pigs
gained 75.4 g protein d-1; appetite-fed controls gained 67.4 g d-1.
Refed pigs did not consume more food, or deposit protein more rapidly,
than controls of the same age or body weight. Twenty-eight pairs of
entire male pigs were grown from 5.6 to 25 kg on two diets of differing
ingredient composition and nutrient density. There were no differences
in carcass composition at 25 kg or daily feed intake (0.81 vs 0.76 k g ).
Pigs fed the diet of higher ingredient quality and nutrient density
reached 25 kg fourteen days sooner and ate 8.9 kg less in total. Postweaning growth was constrained by the poorer quality diet.
III. Compensatory nitrogen retention. Seventy-one Large White barrows
were fed various sequences of dietary nitrogen intakes over 30 days.
Following nitrogen deprivation, compensating animals retained 2.7
(Trial 1) and 4.2 (Trial 2) g N d-1 more than controls. Evidence suggests
extra nitrogen to be used to replenish labile nitrogen stores depleted
during nitrogen deprivation.