Nutrition is the Key

Balanced nutrition is vital for supplying energy and improving feed conversion efficiency for profitable sheep and beef production.

Proper mineral nutrition contributes to a strong immune system, reproductive success, improved milk production and calf/ lamb growth.

Have you got balanced feed for a profitable sheep & beef production?

Worldwide the predominant feed for sheep production is “pasture & forage,” and the productivity/quality of the pasture, rangeland, and forage crop can influence success of sheep production (Chiba, 2014). Soil fertility is an important factor in maintaining the yield and quality of pasture / forage and it is often achieved through the input of nutrients to support healthy plant growth. Most of the essential nutrients are supplied naturally to the plant by the soil, but all nutrients are not always available to plants at the right proportion. So it is necessary to supply nutrients and improve the nutrient density in plants through an application of manure, chemical fertiliser, or by seeding legumes to fix nitrogen.

The purpose of supplying nutrients from organic or inorganic source to pasture/crop is to provide a balanced feed ration for normal health, growth and reproduction of animals because nutrients in the feed are generally utilised by animals to meet their nutritional requirements. Plant materials can be tested for mineral nutrients or feed quality and based on the animal dietary mineral balance (ADMB) report, animal requirements and dietary intake per nutrient for a specific livestock class can be recognised. Nutrient demands among animals may vary at different stages of their growth and therefore, feeding is more than just providing their immediate needs at these stages. It also affects future production because inadequate feeding during key periods of embryonic, foetal and early postnatal growth influence subsequent performance. Also effective planning of diets to provide the correct levels of nutrients can reduce overall feed costs (HCC, 2006). Therefore, farm profitability is linked directly with the correct use of fertilisers to produce high-quality pastures, stocked at an appropriate grazing pressure, with livestock of high genetic merit.

Since animal diet is mainly plant regulated, an imbalance in plant nutrient ratios can create animal health problems. For example, a proper Ca: P ratio (2 to 2.5:1) is required to minimise urinary calculi problem in sheep. However, calcium and phosphorus are interrelated in the development and maintenance of the bones and teeth. Forages and legumes are a good source of calcium, whereas grains are a good source of phosphorus. Too much of either calcium or phosphorus can reduce the availability of the other. If the ratio of Ca: P is inverted and phosphorus exceeds calcium, absorption of calcium in the digestive tract is reduced, and the animal will metabolize calcium and phosphorus from bone. This can result in less bone growth, brittle bones, and “water belly” or kidney stones (Comerford, 2014). Similarly, the level of potassium in plants is generally high and high potassium reduces the availability of calcium and/or magnesium so that grass tetany risk is increased, thereby causing hypomagnesaemia. To avoid these health issues, a nutrient balance need to be properly maintained as per the animal dietary mineral requirement.

Role of minerals in raising sheep and beef

Minerals are essential components in animal diets and they serve many functions within an animal. They are important for promoting optimal fertility, immunity, growth, bone development, enzyme activation, muscle contractions, regulating acid-base balances and are a component of hormones critical for maintaining the well-being of animals. The primary objective of adding minerals in animal diet through plants is to maximise the rate of weight gain to get lambs to market as early as possible. Additional benefits of this strategy are improved feed efficiency and lower fixed costs.

Major minerals for sheep & beef production

Calcium (Ca) and phosphorus (P) are two of the most abundant minerals in the body, comprising about 99% of the calcium in the body, found in the skeleton, while 80% of the phosphorus is in bones and teeth. Calcium is the most demanding nutrient in animal diet due to its structural function (Underwood and Suttle, 1999) and it is required for the functioning of several intra- and extracellular processes including muscle contraction, nerve transmission, blood clotting, and for regulation of many hormones (Andriguetto et al., 1993). The soil solution usually provides an adequate supply of calcium to plants. To achieve an optimal uptake of calcium, boron is essential. Both calcium and boron are less mobile in plants and they are required continuously all over the season. The most important feature of calcium nutrition is the ratio of calcium to phosphorus. Data analysis conducted on plant samples collected from 12 different monitoring sites showed a strong and positive correlation between the plant boron content and the Ca: P ratio in these samples. Therefore, the level of boron is a key factor in improving the level and uptake of calcium in plants.

Phosphorus plays a key metabolic role and has more physiological functions than any other mineral. It is essential for the development and maintenance of skeletal tissue, maintenance of osmotic pressure and acid base balance, energy utilisation and energy transfer, protein synthesis, transport of fatty acids, amino acid exchange, appetite control, efficiency of feed utilisation, and fertility. Deficiencies of phosphorus have long been associated with reproductive problems with cattle, and in many cases phosphorus was overfed as a hedge against these problems (Fluharty, 2005). However, recent research with dairy cattle has shown (Wu, 2000; Dou, 2002) that reproduction is not compromised if the adequate amount and ratio of phosphorus is added to the diet. Excess phosphorus in the diet is excreted through faeces, and overfeeding has become a major issue for phosphorus-based nutrient management. Phosphorus in forages is also depleted with increased maturity of plants, drought conditions, and winter grazing. For beef cows, phosphorus requirements are relatively low, and, like calcium, are met with well-managed pastures (Comerford, 2014).
Potassium (K) comprises about 5 percent of the total mineral content and muscle contains most of the total potassium in the bodies of animals. Potassium functions in the intracellular fluids the same as sodium does in the extracellular fluids. Potassium is required for proper muscle development and it is involved in many body functions including maintaining water balance, osmotic pressure, acid-base balance, enzyme activities, metabolising carbohydrates and proteins and regulating neuromuscular activity (along with Ca) and heartbeat. Potassium deficiency may commonly be manifested by depressed growth, muscular weakness, stiffness, decreased feed intake, intracellular acidosis, nervous disorders, reduced heart rate, and abnormal electrocardiograms. The first sign of potassium deficiency is reduced feed intake. Potassium must be supplied in the daily ration because it is a mobile nutrient and there are not any appreciable reserves (Leeson et al., 1998). Most forages are adequate to excessive in potassium content, and the needs of grazing cattle are generally met. One possible result of excessive potassium (usually associated with grazing legumes in grass-legume pastures or in grasses in early spring) is a reduction in magnesium intake that results in grass tetany. Milliequivalent ratios of K/(Ca+Mg) above 2.2 in forage dry matter are considered hazardous.

Magnesium (Mg) is an important mineral for grazing cattle because of the association with grass tetany. Grass tetany is usually seen in cattle in the early spring when there is lush grass growth and cool, wet weather and is caused by a deficiency of magnesium to the cattle. Magnesium is important for enzyme activation, glucose breakdown, genetic code transmission, membrane transport, nerve impulse transmission, and skeletal development. Signs of magnesium deficiency include excitability, anorexia, increased blood flow, convulsions, frothing at the mouth, prolific salivation, and soft tissue calcification. Young cattle can mobilize large amounts of magnesium from bone, but mature cattle are unable to do this, and they must receive regular and adequate magnesium supplies from the diet (Parish and Rhinehart, 2008). Application of magnesium to pastures should be done based on soil tests, as excessive levels in the soil limit calcium availability. Forage magnesium concentrations depend on plant species, soil magnesium levels, plant growth stage, season, and environmental temperature. Legumes usually contain higher magnesium levels than grasses (Parish and Rhinehart, 2008).

Sodium (Na) is vital for animals but is not necessary for plant mineral nutrition. It plays a critical role as the principle cation in the extracellular fluid and in the regulation of the composition of the blood in all animals, ensuring that all the cells of the body are maintained in a constant environment. Sodium is essential in maintaining a constant pH in the rumen environment (rumen homeostasis) too. Sodium levels in many New Zealand pastures are relatively low due to continued leaching and the low proportion of farmers adding salt to their fertiliser requirements. Signs of deficiency include loss of appetite, abnormal licking and chewing, haggard appearance and loss of production.When salt is applied to pastures it dissolves rapidly and is taken up quickly by plants.

Sulphur (S) influences the yield and quality of pasture and it is essential for both plants and animals. It is a building block in several amino acids (methoinine, cysteine, and cystine) and B vitamins (thiamin and biotin) along with other organic compounds. Sulphur functions in the body in detoxification reactions and is required by ruminal microorganisms for growth and normal cell function. Sulphur deficiencies can reduce feed intake, digestibility, rumen microorganism numbers, and microbial protein synthesis. Sulphur in feedstuffs is found largely as a component of protein (Parish and Rhinehart, 2008). Sulphur is important for improving the efficiency of applied nitrogen to pasture.

Nitrogen (N) applied on pasture can improve feed quality and it is an essential element in animal production too. Plants need nitrogen to make the proteins they require for growth. The availability of soil nitrogen is a major growth-limiting factor for all New Zealand pastures. Pasture depends on nitrogen fixed by bacteria, such as those in the root nodules of legumes like clover and lucerne, mineralised N from soil organic matter, or the N supplied by fertilisers. Spring application of nitrogen would improve pasture quality by increasing the leaf to stem ratio and delaying heading in some situations. Clover is an essential nitrogen source for beef and sheep and it usually contains 4-6% nitrogen in its leaves, whereas the concentration in grass is variable, often only 2-3% unless receiving fertiliser nitrogen (Cosgrove et al., 2002). Proteins are required for formation of body tissue. The requirement of both energy and protein by any animal depends on the degree of production expected from the animal. Prolonged deficiency of both proteins and energy would result in loss of condition and inability to be productive.

Trace minerals for sheep & beef production

Important trace minerals to consider in New Zealand beef and sheep farming are selenium (Se), copper (Cu), iodine (I), cobalt (Co) and zinc (Zn).

Selenium is an ultra-trace element essential for the nutrition of all animals. It acts as an antioxidant to protect the integrity of cell membranes and maintains the integrity of the immune system. Selenium deficiency can reduce conception rate, lamb and calf survival and growth rate. The classic symptom of selenium deficiency is ‘white muscle disease’ of lambs, the muscle most affected is the heart. This results in heart failure or paralysis of the hind limbs and resulting in a high mortality rate for new born animals. Selenium is passed from the placenta to the fetus during late gestation, and proper selenium supplementation to does and ewes will assist in preventing white muscle disease in kids and lambs. So it is a critical nutrient during during gestation. Sulphur at high levels in the diet will reduce selenium absorption by grazing animals. Care must be taken when applying selenium as this element is also potentially very toxic. The level of selenium that is considered adequate in pasture and animal feeds is 0.10 mg/kg.

Cobalt is required by animals to make vitamin B12. Vitamin B12 is required for the absorption of some of the products of rumen fermentation so deficiency produces symptoms rather like starvation of the animal. Deficiency symptoms include reduced growth rate, decreased appetite, decreased milk production, rough hair coat, weight loss, weak animals, increased susceptibility to parasites, increased risk of disease or infections and increased mortality of young animals. Lambs have the highest requirement followed by calves, adult sheep and adult cattle. Cobalt is added as a fertiliser supplement and is taken up by the plants thereby providing the animals’ requirements. Sheep, goats and deer pastures should also be maintained at a level of between 0.10 and 0.15 mg/kg especially for young animals being weaned onto pasture.

Copper is an essential trace element required for both plant growth and animal nutrition. Sheep have a lower requirement for copper than cattle or deer and are more likely to suffer from copper toxicity due to a relatively low ability to excrete excessive dietary copper. Copper is required for the normal growth of bone, hair and skin so animals that are growing rapidly and female animals in late pregnancy are most likely to show copper deficiency. Molybdenum reduces the absorption of copper by animals. Foliar application of copper to pasture or feed is an option for supplying copper. Sheep have adequate copper at levels between 6 and 10 mg/kg and cattle require about 10 mg/kg.

Iodine has an indirect effect on reproduction through its action on the thyroid gland.
Iodine deficiencies may indirectly cause early embryonic death, abortion, stillbirths, prolonged gestation (time the calf is carried in the uterus), and an increase in the incidence of retained placenta. Lactating cows and sheep are more likely to suffer from iodine deficiency than non-lactating stock due to the loss of iodine in milk. A minimum level of iodine considered to be adequate for animal nutrition is 0.5 mg/kg.

Zinc is an essential trace element for the nutrition of pasture and all ruminant animals. Deficiency of zinc typically results in reduced growth rates of young stock, reduced feed consumption, reduced efficiency of conversion of feed energy to milk or live-weight gains, dermititis or scaley skin, swollen tissue around the hooves and foot problems. Development or growth of testicles and sperm production is likely to be affected. The desired range of zinc levels considered adequate in pasture and animal feeds is 30 to 50 mg/kg.

Tony Joseph BScAg, MScAg, PhD.                 027 680 9707