A review of factors influencing litter size in Irish sows

Table 4 Energy requirement of sows during lactation and sow weight loss during lactation (kg over 26 days) associated with three different lactation feed curves (see Appendix 2).

	Energy requirement during lactation				Curve 1		Curve 2		Curve 3
Sow weight (kg)	Maintenance (MJ DE)¹	Milk (MJ DE)²	Total/day (MJ)	Total/day (kg)	Fed (MJ)	Weight loss³(kg)	Fed (MJ)	Weight loss³(kg)	Fed (MJ)	Weight loss³(kg)
180	22.6	69.0	91.6	6.45	74.3	23.4	85.5	8.4	98.3	-9.1
190	23.6	69.0	92.6	6.52	74.3	24.7	85.5	9.6	98.3	-7.8
200	24.5	69.0	93.5	6.58	74.3	26.0	85.5	10.9	98.3	-6.5
210	25.4	69.0	94.4	6.65	74.3	27.2	85.5	12.1	98.3	-5.3
220	26.3	69.0	95.3	6.71	74.3	28.4	85.5	13.3	98.3	-4.1
230	27.2	69.0	96.2	6.77	74.3	29.6	85.5	14.5	98.3	-2.9
240	28.1	69.0	97.1	6.84	74.3	30.8	85.5	15.7	98.3	-1.7
250	28.9	69.0	97.9	6.90	74.3	32.0	85.5	16.9	98.3	-0.5
260	29.8	69.0	98.8	6.96	74.3	33.2	85.5	18.1	98.3	0.7

1 DE for maintenance (MJ DE/day) = ((110 × BW^0.75)/1000) × 4.1853 [26] where BW is body weight.
2 DE for milk (MJ DE/day) = ((((6.83 × ADG × pigs) - (125 × pigs)) × 4.1853)/1000)/0.96) [26] where ADG is the daily gain of sucking pigs (assumed here as 250 g/day) and pigs is the number of piglets sucking per sow (assumed here as 10).
3 (Total energy requirement during lactation - Energy fed )/((5 × 4.1853 × 0.88)/0.96) = weight loss [25].