Effects of the Environment on the Nutritional Needs of Grazing Livestock

Profitability of grazing operations is related to productivity per acre. Productivity is determined, among other factors, by the efficiency with which the animal harvests the forage. Efficiency can be defined as nutrients consumed per unit of product produced (feed to gain). Costs incurred in this process which are not translated into products are sources of inefficiencies. Costs are not only related to dollars spent by livestock producers but also to nutrient inputs and outputs (balance) incurred by an animal. Just as in your bank account, the animal has a budget in his body with accretions and withdrawals, and when one exceeds the other they can either build up or deplete reserves. Nutrients consumed by cattle provide maintenance and production. Energy, one of the most critical nutrients for grazing ruminants, is supplied by the end products of nutrient fermentation and absorption. Energy is used to maintain body temperature, is lost as heat of fermentation, or is used while performing work (e.g. walking). An energy balance is the result of the difference between inputs (energy intake) and outputs (energy expenditure).When positive, it may result in body weight gain and increased production and reproduction. A negative energy balance, on the other hand, can decrease production and/or body condition and ultimately affect fertility