China is a natural market for our exports, not only for offals but also for lean cuts as the demand from 300 million middle-class earners exerts its pressure on pork consumption. The large influx of tourists and business visitors throughout China eat in western-style four- and five-star hotels, with a big demand for bacon, ham and sausages at breakfast. Pig stomachs and pig brains are delicacies in Sichuan Province hot-pot restaurants.

Summit gilt 8113

Trait	Tot	Ave
Total born	213	17.8
Born live	188	15.7
Born dead	22	1.8
Mummies	3	0.3
Pigs Weaned	22	1.8
Wean-serv interv		4.8
Gest. Length		115.4
Lact. Length		22.8

[Record production for a Yorkshire sow that I am aware of was 225 piglets born live over 15 litters owned by Cora Thornton in 1974.]

One of Old Elm Colony’s 3rd parity sows farrowed 18 pigs with 16 liveborn – no runty piglets at all!
Springpoint Colony farrowed 3 gilt litters with 46 liveborn pigs – all other litters were so large there was nowhere to foster to.

For situations in which final selection of replacement gilts is made at a market weight of approximately 115 kg, the feeding and management program of the gilts after selection should be based on the age and backfat level at selection, with the objective of having gilts with 16-18 mm P2 backfat at time of breeding. A common situation is that gilts arrive on-farm at 145 to 155 days of age, weighing 95 to 105 kg and with 11 to 13 mm P2 backfat. Transportation stress, relocation and mixing usually result in a significant reduction in average daily feed intake and consequently in average daily gain. Feed intake may drop as low as 1.7 kg/day in the first week and average only 2.6 kg over the first three weeks after arrival. Expected growth rates will be about 650 g/day with a feed conversion efficiency of 4:1. The composition of the 650 g/day will be approximately 450 g lean plus bone, with 200 g fat. With this level of fat gain, the gilts will gain about 0.9 mm P2 backfat per week, assuming that it takes about 1.5 kg fat deposition to achieve a gain of 1 mm P2. Therefore, on a conventional gilt developer diet, gilts with 11 to 12 mm backfat upon arrival will have to be in the gilt pool for 5 to 6 weeks to reach the target backfat of 16 to 17 mm at breeding. However, if they are fed a fat-enhancing diet, they can gain about 2 mm backfat per week.

Table 1. Gilt diets fed from selection to time of breeding

	Gilt Developer	Fat Enhancing
Age, days	>145	<145
Backfat, mm	>14	<14
Mcal DE/kg	3.25	3.45
Crude protein, %	>14.5	<13.5
Lysine, %	0.65	0.55
Calcium, %	0.80	0.85
Phosphorus, %	0.70	0.75

Table 2. Vitamin/mineral levels for replacement gilts

Minerals	Gilt Finisher	Gilt Developer
Selenium, mg/kg	0.30	0.30
Iron, mg/kg	40	150
Copper, mg/kg	10	120
Vitamins
Biotin, mg/kg	0.30	0.40
Folic acid, mg/kg	3	4
Choline, mg/kg	750	1250
Riboflavin, mg/kg	8	10

If we are serious about doing the best for our replacement gilts then we should measure backfat when they arrive on farm and feed and manage them based on backfat levels.

Three possible management strategies might be:
Strategy 1

For gilts that are 145 days of age or more and have greater that 14 mm P2 backfat at time of selection, these gilts can be fed ad libitum a gilt developer diet similar to the one shown in Table 1.
The premix in this diet should be similar to that used for grower pigs of 25 to 50 kg and should ensure a higher intake of calcium, phosphorus, copper, iron, zinc, selenium, folic acid, biotin, choline, pyridoxine and riboflavin than that supplied to finisher hogs (Table 2). This increased intake of vitamins and minerals will enhance body reserves that may be used during future reproduction and may reduce culling rate due to locomotor problems.

Strategy 2

For gilts that are less than 140 to 150 days of age at time of selection (115 kg) and have less than 14 mm P2 backfat, such gilts should be fed a diet similar to the “fat enhancing” diet shown in Table 3. This diet should reduce growth rate slightly and should allow ad libitum-fed gilts to gain 1.5 to 2 mm P2 backfat per week. Therefore, these gilts should weigh about 125 kg and have 19 to 22 mm P2 backfat at breeding at their second estrus.

Strategy 3

Some producers do not like to breed gilts that are less than 7 months of age. A strategy used to slow growth rate is to restrict-feed a diet similar to the fourth phase diet shown in Table 2. This program will allow for gilts to increase in age but not become excessively large at time of breeding at the second or third estrus. In a trial commissioned by the NPPC in the USA (Culbertson and Mabry, 1995) restricting energy intake or feeding a low protein diet (13% CP) high energy (3.5 Mcal ME/kg) from 82 kg liveweight to 180 days of age resulted in a higher proportion of sows surviving through four parities (56 and 53% respectively) compared to 35% survival rate for sows fed a high protein (18% CP) normal energy (3.2 Mcal ME/kg) up to the time of breeding. These data suggest restricted feeding in the late finishing period will not reduce reproductive performance or lifetime productivity. But it won’t enhance it either, it will just slow growth rate. Also, if gilts are restricted in feed intake in the late finishing period or after selection, restriction should not be greater than 15% below ad libitum intake levels and the restricted gilts must be ad libitum fed for 10 to 12 days before breeding in order to optimize ovulation rate. It is important to note that in the NPPC trial all gilts, including the restrict-energy gilts were fed ad libitum. Also, just because gilts are fed ad libitum does not mean that their feed intake is high. As mentioned previously, newly arrived gilts may have average daily feed intakes as low as 1.7 kg during the first week after arrival. If such gilts come in heat that first week or 10 days they may have lower conception rates and lower subsequent litter size. So, try to ensure that gilts are eating 2.5 kg of feed per day for at least 10 days before breeding. If gilts are put on a restricted feeding program, either total feed, energy or protein level they must be put back to normal levels of feed, energy or protein for 10 to 12 days before being bred. This ‘flushing’ will ensure normal ovulation rates and embryo survival levels.