By Chantal Farmer
Editor’s note: Chantal Farmer is a research scientist at Agriculture and Agri-Food Canada’s Sherbrooke Research and Development Centre. She can be contacted at firstname.lastname@example.org.
Modern piglet problems for modern sows
Intra-uterine growth-restricted piglets occur more frequently when litter sizes are large, making piglets more susceptible to death due to overcrowding in utero.
Low birth weights, lack of energy reserves and poor immune protection also leave piglets vulnerable, and this situation has become worse with the current use of hyperprolific sow lines. Assisting newborn and suckling piglets to maximize their survival and growth is essential, given the trend of increasingly larger litters.
Intra-uterine growth-restricted piglets are characterized by their dolphin-like head shape (Figure 1) and their reduced growth rate, resulting ina poorer capacity for ingestion and use of colostrum – a sow’s nutrient-dense milk that is available to piglets only immediately after birth. This is most important considering that the early intake of 250 grams of colostrum is crucial for the survival and growth of piglets.
Various nutritional strategies can be used in gestation and prior to farrowing to help suckling piglets, including supplementary feeding of arginine – an amino acid – in gestation, which may improve nutrient supply to the placenta and increase birthweight. Additionally, feeding a source of n-3 polyunsaturated fatty acids in late gestation – such as fish oils – to stimulate fetal brain development and vigor can decrease the interval between birth and first suckling.
Sow backfat thickness matters
Recent findings have shown that body condition of gilts at the end of gestation must be considered to achieve optimal sow lactation performance (Table 1). A gilt that is too thin (with 12 to 15 millimetres of backfat at the P2 site of the last rib) on day 110 of gestation has less milk-secreting tissue in her udder than a gilt with 17 to 26 millimetres of backfat. This difference was achieved by offering varying amounts of feed throughout gestation (1.30, 1.58 or 1.83 times the maintenance requirements). Body condition is also important for colostrum yield. Sows with moderate body conditions (17 to 23 millimetres of backfat) produced more colostrum (4.0 kilograms versus 3.2 kilograms) compared with fatter sows (more than 23 millimetres of backfat).
Feeding during the transition period – starting on day 108 of gestation – has received quite a bit of attention recently. The amount of energy reserves of sows at the time of farrowing has a great effect on farrowing duration and on the incidence of piglet stillbirths and hypoxia – a state caused by insufficient oxygen levels in body tissues.
Lessons for hog farmers
Maximizing the energy intake of sows prior to farrowing is important. This can be achieved in various ways, such as increasing energy intake (to 33.8 megajoules versus 28.2 megajoules of net energy per day), feeding a readily available energy source, feeding a high-fibre diet to prolong energy uptake via hind-gut fermentation, or feeding sows three times a day. Farrowing duration and stillbirths have been shown to increase if a sow has not eaten in the 3.1 hours prior to farrowing.
Management strategies during farrowing and lactation are also needed to maximize piglet performance. Farrowing supervision and piglet assistance at birth – such as drying, placing close to a teat, providing an extra source of energy to low-birthweight piglets, split-suckling and cross-fostering – will help decrease piglet mortality.
Sows do not produce enough milk to sustain maximal growth of their piglets. A teat that is not suckled in first lactation will produce less milk in second lactation. First-parity sows should have all their teats suckled for the first 48 hours after farrowing to maximize milk yield in the next parity.
There must also be enough teats for all piglets in a litter, but if that is not the case, the use of nurse sows or providing artificial milk can help. Artificial rearing of a whole litter should be used only when piglets cannot be reared normally, since artificially reared piglets will grow slower than sow-fed piglets, taking five more days to reach market weight.