Changes

==Description==

==Description==

SARA is increasingtly being seen as a major nutritional

 

problem affecting dairy cows (Nordlund 2001). It is

In the last 20 years, selective breeding and improved genetics have dramatically increased the individual cow's milk yield and hence the energy requirements for lactation. In order to meet these increased energy demands and avoid prolonged negative energy balance in early lactation, the energy density of the ration has also been increased. This has been achieved by feeding high levels of concentrate feed and energy-rich maize silage. Although these are effective in helping to meet energy requirements, they also contain large quantities of rapidly fermentable carbohydrates that cause increased production of acid in the rumen. The results in a fall in rumen pH below the optimum range of 6-7. This is known as subacute rumenal acidosis.

 

It is

insidious and, in many cases is never recognised or

insidious and, in many cases is never recognised or

diagnosed. let alone prevented. It is a group problem and

diagnosed. let alone prevented. It is a group problem and

SARA using this threshold.

SARA using this threshold.

 

Ruminant animals are adapted to digest and metabolize predominantly forage diets; however, growth rates and milk production are increased substantially when they consume high-grain diets. One consequence of feeding excessive amounts of rapidly fermentable carbohydrates in conjunction with inadequate fiber to ruminants is subacute ruminal acidosis, characterized by periods of low ruminal pH, depressed feed intake, and subsequent health problems. Chronic disease conditions secondary to subacute ruminal acidosis can negate the production gains accomplished by high grain feeding. Dairy cattle, feedlot cattle, and feedlot sheep are all at high risk for developing this condition. Although dairy cattle are typically fed diets that are higher in forage and fiber compared with feedlot animals, this advantage is offset by their much higher dry-matter intakes.

Ruminant animals are adapted to digest and metabolize predominantly forage diets; however, growth rates and milk production are increased substantially when they consume high-grain diets. One consequence of feeding excessive amounts of rapidly fermentable carbohydrates in conjunction with inadequate fiber to ruminants is subacute ruminal acidosis, characterized by periods of low ruminal pH, depressed feed intake, and subsequent health problems. Chronic disease conditions secondary to subacute ruminal acidosis can negate the production gains accomplished by high grain feeding. Dairy cattle, feedlot cattle, and feedlot sheep are all at high risk for developing this condition. Although dairy cattle are typically fed diets that are higher in forage and fiber compared with feedlot animals, this advantage is offset by their much higher dry-matter intakes.

Field observations suggest that periparturient cows are at risk of subacute ruminal acidosis because of the time required for the rumen microflora and papillae to adapt to increased intakes of concentrates immediately before parturition and during early lactation when feed intake increases rapidly to meet the energy needs of high-producing dairy cows. The adaptation of the ruminal microflora and papillae from a system appropriate for forage to a system capable of utilizing high-energy lactation rations requires a gradual change over a period of 3-5 wk.

Field observations suggest that periparturient cows are at risk of subacute ruminal acidosis because of the time required for the rumen microflora and papillae to adapt to increased intakes of concentrates immediately before parturition and during early lactation when feed intake increases rapidly to meet the energy needs of high-producing dairy cows. The adaptation of the ruminal microflora and papillae from a system appropriate for forage to a system capable of utilizing high-energy lactation rations requires a gradual change over a period of 3-5 wk.