Nutritional issues with grain feeding

  • Insufficient protein
  • Lack of calcium
  • Clinical & Sub-clinical Acidosis
  • Urinary Calculi (bladder stones)

The effect of grains limitations are magnified in those sheep that have the largest demands on nutrition, in particularly growing lambs and weaners.

Understanding the nutritional needs of lambs and weaners is important in overcoming the limitations of cereal grain but first lets understand what cereal grains offer.

Table 1 shows the average content of key nutritional ingredients of three of the major cereal grains.

TABLE 1 – DRY MATTER BASIS (TYPICAL ANALYSIS)
Grain Energy (ME)(1) MJ/kg Crude Protein (avg) % Calcium g/kg Phosphorus g/kg
Wheat 13.0 12 0.5 3.0
Barley 12.0 11 0.4 3.0
Triticale 13.0 12 0.4 4.4

The crucial role of Protein

To achieve the objectives of lamb finishing and growing weaners, energy and protein need to be well balanced and key minerals need to be available.

Cereal grains provide high amounts of energy. However, this is not balanced with the high levels of protein needed by growing lambs. When there is an excess of energy it will accumulate as fat which reduces carcase quality.

Increasing the protein of the cereal diets will better utilise the available energy resulting in better growth rates and carcass quality (Graph 1).

Graph 1 is based on data provided by the NRC and shows the gap between grain crude protein levels and those required to reach reasonable growth rates. It also demonstrates that by increasing protein levels by around 1% you can achieve improvements in growth rates. The amount of growth may be more or less depending on genetics and management practices.

The crucial role of Calcium

To support the growth of lean muscle mass and a strong skeleton other minerals need to be available, in particular calcium.

Calcium is vital for bone formation and important for muscle contractions, blood clotting and nerve function.

Deficiency symptoms in growing lambs include lethargy, weak bones and poor growth.

Cereal grains contain very low levels of calcium. Cereals only provide 10% of the daily requirement of a growing lamb/weaner (Graph 2).

Animal Health

Grain feeding lambs and weaners also presents animal health issues:

Acidosis (grain poisoning): Clinical and Sub-Clinical

Cereal grains contain a very good source of energy, starch.

But diets high in starch can increase the acidity of the rumen and lead to acidosis, which in the worst cases leads to death.

The symptoms of acidosis include scouring, abdominal pain, sluggishness, bloated or dehydrated appearance and an arching of the back.

However, it is the acidosis that you don’t see (subclinical) that may be restricting growth rates because the rumen is not operating efficiently.

All Nutrimax products contain Acid Buf® which will reduce the risk of acidosis.

Coccidiosis

The intensive nature of some feedlotting operations can increase the risk of coccidiosis. Once an animal is infected it can spread quickly through the flock. It is better to prevent infection rather than to cure it, as once it occurs it damages the lining of the rumen and affects nutritional intake.

All Nutrimax products contain Bovatec® that helps control coccidiosis.

Urinary Calculi (bladder stones)

Bladder stones can occur where diets are low in calcium relative to phosphorus. When a bladder stone occurs it can block the lamb’s urinary tract, causing a retention of urine that leads to discomfort and depression meaning the animal will go off feed and can further develop into a rupture and result in death.

The recommended balance of calcium to phosphorus is 2:1.

Cereal grains contain very low levels of calcium and relatively high levels of phosphorus (see Graph 3).

Nutrimax products contain good levels of calcium that help offset this imbalance and also includes ammonium salts for added protection.

Feed Efficiency

Key to lamb finishing is maximising feed conversion and daily weight gains.

Ionophores have been shown to do both by regulating ruminal microbial fermentations to allow better utilisation of dietary energy and protein.

All Nutrimax products contain the latest ionophore, Bovatec®.

Environmental: Heat

To take advantage of market conditions, many lamb finishing enterprises operate during the hotter months of the year.

This can be stressful to lambs and reduce production. Providing good water quality and availability along with adequate shelter helps reduce this stress.

Nutrimax Lamb Feedlot 10% and Nutrimax Ruminant Feedlot 20% contain betaine which can potentially assist sheep in these hot conditions.