Partial Calculation of Metabolizable Energy and Crude Protein Requirements of Lactating Sows.
The influence of metabolizable energy and crude protein level in the ration of sows on the reproduction performance data was investigated in four trials. On the basis of the experimental data and partial requirements the energy and protein balances of lactating sows were calculated.
1. Energy balance. Sows fed at a low (below 65 MJ) metabolizable energy level had a negative (according to ARC, 1981) energy balance – 9.9 MJ. An average daily weight loss of these sows was 0.44 kg.
Sows fed at a medium (65…70 MJ) energy level had an energy lack of 4.6 MJ/day (by ARC, 1981). At the same time the daily weight loss of sows averaged 0.56 kg. To meet this modest energy deficiency, it appears, the energy content of body tissues used for milk synthesis was only 9.7 MJ/kg. Such low energy content is explicable only in the case, when body tissues used for milk synthesis replaced partly by water.
Sows fed at a high (over 70 MJ) energy level had a higher milk yield (according by Walker, Young, 1992) and energy deficient (by ARC, 1981) was 13.8 MJ/day. Body weight loss of these sows was an average 0.47 kg a day.
2. Protein balance. The protein balance was most negative in sows fed at a low (below 800 g) protein level.
Sows fed at a medium (800…900 g) protein level had (by ARC, 1981) the protein lack of 112 g/d concurred with 0.56 kg daily weight loss.
The protein requirement of sows fed at a high (over 900 g) protein level was almost met, the protein balance (by ARC, 1981) was only a little (20 g) nega-tive. Weight losses (0.47 kg/d) of these sows probably composed mainly of fat.
High metabolizable energy and crude protein level in the diet of pregnant sows had no influence on the survival of piglets, but a high feeding level of lactating sows had a little advantage compared with low energy and protein intakes. Sows obtaining more energy and protein with the feed had a greater number of piglets in the litter at the age of three and eight weeks.
Litters from the sows fed at a low metabolizable energy and crude protein level during lactation were heavier than those from the sows fed at a medium and high level, which was caused by increased creep feed consumption of these piglets.
Key words: swine nutrition, energy requirement of sows, protein requirement of sows.