Sow nutrient requirements calculation formula
The calculation formulas in the table below are taken from "Nutrition of Sows and Boars"; compared with the modern NRC2012 method, they have typical characteristics of the 1980s and 1990s. But from a historical perspective, their significance is still extraordinary. Formulators may no longer use them for nutritional calculations, but they can still be used to learn about the sow's organism. It is recommended that you use these formulas to calculate step by step, so that you can deepen your understanding of sow nutrition
Nutrient Requirements Calculation for Pregnant Sows
Calculation of energy and lysine requirements for gestating sows (sow and boar nutrition):
1. Total birth weight of piglets = number of piglets x birth weight of piglets
2. Fetal weight = total birth weight of piglets ÷ 0.75; (total birth weight of piglets accounts for 75% of total weight loss during delivery)
3. Breast tissue weight during pregnancy: 4.6kg (empirical value)
4. Total reproductive gain = total birth weight of piglets + breast tissue weight
5. Body weight gain of sows during pregnancy = total weight gain - reproductive weight gain
6. Body weight of sows after delivery = breeding weight + sow weight gain - breeding weight gain
7. Average weight during pregnancy = (breeding weight + postpartum weight) ÷ 2
8. AFRC (1990): The highest average nitrogen storage capacity when pigs weigh 100 kg is 16g/d (NR max); in the following 7 or 8 years, with genetic improvement, it is believed that 18g/d (112.5 g protein) shall prevail. This is an average, NR may be 4-6 g/d low in early pregnancy and 4-6 g/d high later in pregnancy.
9. AFRC (1990) suggested: the mature weight of sows is 320kg, and for every 20kg increase in breeding weight of sows, the NR max value will decrease by 1g/d (protein 0.31g/kg weight gain, 1/20*6.25=0.31).
10. Based on the above: increase protein (g/d)=112.5-(average body weight-100)×0.31
11. Total increase in body protein during pregnancy (kg) = daily increase in protein × 114 ÷ 1000
12. 1 kg of body protein combined with 4.347 kg of water in the body, protein + water = lean mass, therefore: lean mass kg = protein weight gain × 4.347
13. Body weight gain = intestinal content + ash + lean meat + fat; intestinal content and ash account for 10% of the total weight gain, so body fat gain kg = 0.9 × body weight gain - lean meat gain
14. Body fat (kg)=0.161×body weight kg+1.44×P2(mm)-11.6
P2(mm)=(body fat kg+11.6-0.161×weight kg)÷1.44
15. The relationship between P2 value of backfat thickness measured by ultrasound and body condition was summarized as a linear formula by Whittemore (1980). When body condition score changes by 1 unit, P2 value of backfat thickness changes by about 6mm. P2 (mm) = 5.8 × body condition score - 0.7.
16. Maintain energy requirement MER (DE MJ/d)=0.455×average body weight 0.75; obese people subtract 5%, and lean people increase by 5%.
17. Reproductive energy requirement RER (DE MJ/d) = tissue weight gain × 6.7 ÷ 114
18. Energy requirement for maternal weight gain BER (DE MJ/d) = total maternal weight gain × 21.4÷114
19. The total daily energy requirement TER=MER+RER+BER; the total energy requirement should also be adjusted according to the maternal score: for every unit change in the body condition score, the feed energy requirement will change by 7.5%.
20. 1 kg of protein contains 23.8MJ digestible energy, and the net utilization efficiency of protein in the body during pregnancy is 0.6, so 1 kg of protein requires 23.8÷0.6=39.7MJ of metabolic energy, or 41.3MJ/d of digestible energy; 1 kg of fat contains 39.7MJ of energy, The efficiency for fat deposition during pregnancy is 0.8, and 49.6MJ of metabolizable energy or 51.7MJ of digestible energy is required to deposit 1 kg of fat. Total energy requirements = maintenance needs + protein deposition needs + fat deposition needs.
21. Fuller et al. (1989): Daily maintenance requires lysine MLR0.036W0.75 g/day.
22. 1 gram of protein contains 0.07 grams of lysine, and the lysine deposition efficiency is 0.7. The digestible lysine PLR required for protein deposition = daily protein deposition × 0.07 ÷ 0.7.
23. Total digestible lysine TDLR=MLR+PLR; the digestibility of lysine is 80%, then total lysine=TDLR÷0.8. Feed lysine digestibility is 0.9, then digestible lysine in feed = total lysine × 0.9.
24. Under the maintenance of energy, the floor is insulated, and there is no draft, the LCT of sows is 23°C; when the weight of sows increases by 60 kg on the basis of 120 kg, the LCT decreases by 1°C (AFRC, 1990); the feed intake is maintained For each increase of ME80kj/W0.75/d on the basis, the LCT will decrease by 1°C; for each 1°C lower than the LCT, the energy intake needs to be increased by 18kj/W0.75/d. Maintenance requires ME430×W0.75 or DE448×W0.75.
25. Based on 24 items, LCT (°C)=23-(sow weight-120)÷60-((0.96×digestible energy average feed intake MJ/d×1000÷W0.75)-430)÷80
26. Extra energy EER (DE, KJ/d) = (LCT-ambient temperature) × 18 × W0.75÷0.96
27. Energy requirement after temperature correction=TER+EER