Epsilon Archive for Student Projects

Abstract

Salt (NaCl) is an essential element in many plants and in the diets of humans and animals. Salt is even a preservative, protecting against spoilage and coincidentally maintaining life. In most places around the world, pasture and grain are deficient in both sodium (Na+) and chloride (Cl-) and animals have to be fed supplemental salt to satisfy their sodium requirement. Deficiency in chloride is not usual; therefore, the focus of this work is on sodium alone.

Sodium contributes to many processes in the body: for example, the maintenance of body temperature, chemical transport and nerve function. Sodium, together with potassium (K+) and chloride, is one of the most important ions for the body regulates pH and osmotic pressure. Deficiency in sodium is not always easy to detect but can lead to decreased appetite, weight gain, fertility, milk production and even weight loss. Excess of sodium is generally not a big problem as long as the animals have free access to water of good quality.

The sodium requirements for cattle, small ruminants and horses were calculated from National Research Council (NRC) and Swedish recommendations. Their expected sodium intakes from food were estimated to see if the animals were capable of compensating for the sodium deficit by unlimited access to a saltlick. These calculations showed insufficient intake of sodium in most of the cases and that access to saltlicks could not always fulfil animal needs.

A cow (650 kg) producing on average 31 kg energy-corrected milk has a sodium deficiency of between 3.3 and 17.7 g/day, depending on the feeding plan. A sheep 6 weeks before lambing lacks 1.7 g Na/day according to Swedish recommendations, although according to the NRC its sodium requirements are fulfilled. A lactating goat lacks 5.3 g Na/day according to Swedish recommendations and 1.8 g Na/day according to the NRC. For small ruminants, the recommendations for maintenance differ a lot between Swedish and NRC recommendations. The sodium requirements for a horse in normal training are almost fulfilled according to both Swedish and NRC recommendations. A horse in hard training, with big mineral losses in the sweat, lacks 14.3 g Na/day according to the NRC and 19.5 g Na/day according to Swedish recommendations.

This study points out that supplemental salt is needed and that more studies are need to investigate the actual intake by saltlick.