Energy in the diet is measured either by calories (Mcal) as used in the USA and Canada or joules (MJ) as used in Europe. In some countries the kilocalorie (kcal) is used and in others the Megacalorie(Mcal) = 1000 kcal. To convert calories to joules multiply by 4.184.

Thus 1Mcal = 4.184 MJ. The most common nutritional deficiency in pigs is that of energy and the amount available in the diet is usually measured either as digestible energy (DE) or metabolisable energy (ME). (ME = 0.96DE). Digestible energy is the amount of energy which is present in the feed and readily digested and absorbed from the intestine into the body.

The pig could not operate without adequate sources of energy because it is the fuel that supports maintenance and drives the whole of the metabolic processes resulting in the production of meat and milk. Fig.14-5 shows the key factors that contribute to an energy deficient state. If there is poor growth problem in your herd you would be advised to check this list and identify those factors that are likely to have a bearing on your problem and then refer to the index or other chapters relating to the problem area.

Energy requirements are determined by the weight of the pig, its growth rate, the amount required for maintenance and its stage in the reproductive cycle. The requirements for energy in the lactating sow should not be underestimated. Fig.14-6 shows the critical periods of energy demand in the pig through its life and diseases that may be associated if an energy deficiency arises. Daily feed intake and the energy level per kg of feed are crucial factors which help the pig to maintain a positive (anabolic) energy state instead of a negative (catabolic) one. The intake of energy is also essential to maximise reproduction performance (see chapter 5). The relationship between feed intake and energy used by the pig on the one hand and that lost to the environment is a complex one. The survival of the piglet in the first 2 to 3 days of life is highly dependent on a regular supply of energy and if the sows nutrition is inadequate leading to poor quality milk, the susceptibility to disease and piglet mortality rises. Diarrhoea in the neonatal period and up to 14 days of age is often precipitated by intermittent periods of catabolism associated with low environmental temperatures. The introduction of creep feed at an inopportune time can, through indigestion and abnormal fermentation, initiate a sequence of events leading to scour or increased susceptibility to rotavirus, PRRS, joint infections or glässers disease. If you have an intransigent scour problem on your farm and you are feeding creep to sucking piglets stop doing it. Many problems become lesser ones or disappear. See diseases of the sucking piglet in chapter 8.

In the newly weaned pig the quality and availability of carbohydrates and other energy sources are vital if a healthy rapid growing pig is to be produced. Within 12 to 24 hours after weaning most pigs become energy deficient for a short period, which affects the degree of villus atrophy and the rate of their regeneration. The immune system also does not respond efficiently and the results are more disease or a greater incidence. The important changes in management and feeding practices are considered in detail in chapter 9.

The significance of maintaining a positive energy balance in the pig and its role in the precipitation of disease is often not appreciated on the farm. Aspects of this are dealt with in the relevant chapters and specific diseases. Conditions however are highlighted here from field experiences, so that you can assess them in relation to problems on your farm.