Strategies for Feeding Fat to Dairy Cattle
Energy demands exceed energy intake for 80 to 100 days postpartum. Severe weight loss can lead to ketosis, fatty liver formation, reduced reproductive performance, and decreased milk yield.
Fat supplements can provide a concentrated source of added energy without changing ration fibre and carbohydrate dynamics.
Commodity fats refer to feed ingredients that provide fat along with other nutrients (such as protein, fibre, and minerals). Oilseeds, or veggie oil, are referred to as rumen available fat, unprotected fat, and free fat by nutritionists. These sources are usually cheaper source of fat energy to incorporate in the diet. Specialty fats are specifically processed products that provide fat as their prime nutrient. These fats are commonly referred to as ruminal inert fat, protected fat, escape fat, and by-pass fat and are more expensive per unit of energy provided compared to commodity fats. Commodity fats can affect rumen fermentation by absorbing on bacteria and feed particles coating the feed or bacteria lower feed digestibility. Unsaturated fatty acids are more toxic because they bind more to the bacteria and impact the rumen fermentation. Exposure of the unsaturated fatty acids in the rumen due to oilseed processing (whole seed, rolled, ground, or extruded) or oil will impact field results.
The energy values for fat is between 31 and 38 MJME/kg.
RESPONSES TO FEEDING FAT
Summarised research results to various fats, following observations can be seen in the field.
1. Energetically, the conversion of metabolsisable energy to milk energy is highest with
dietary fat compared to forage and concentrate sources or mobilised body reserves. Fat test can be maintained (during negative energy balance) or increased .2 to .3 percentage point. The added fat raises circulating blood lipid levels which contribute 40 to 50 percent of total milk fat precursors.
2. Reproductive performance can be enhanced because cow return to positive energy
balance sooner which can affect follicle size, ovum fertility, and circulating blood progesterone levels.
3. Cows can lose over 120 kg of body weight in early lactation. If cows maintain high milk
yields, it is nearly impossible to gain this lost body condition back prior to the next lactation which can affect future milk production (referred to as sophomore slump in young cows) and reproduction.
4. Ketosis continues to be a serious metabolic risk in early lactation. Cows that lose more
than one kg of body reserve can experience lowered dry matter intake and increased risk of fatty liver formation.
Overall, energy status can be improved with fat supplementation without risking excessive starch and low fibre intakes.
NUTRIMIX NZ Ltd. 1 WWW.nutrimix.co.nz / 0800-TOPMIX / [email protected]LEVELS OF ADDED FAT
Basal diets typically contain 2.5 to 3 percent fat from grass and others feed. High producing cows (more that 500 kgMS/year), could be need extra energy during peak and mating season to achieve their yield potential and be pregnant, for those cows 200-500 gr of bypass fat can be very helpful.
RATION CHANGES WITH ADDED FAT
When supplement fat is added to dairy rations, several adjustments should be considered.
1. Adequate fibre form (20 to 22 percent effective NDF) are needed to maintain
rumen digestion, especially with unsaturated oilseed sources.
2. Calcium should be increased .2 percent above normal levels (from .7 to .9
percent of the ration dry matter). Magnesium levels should also be increased from .25 to .30 percent in the total ration dry matter.
3. Fat does not provide available energy for the rumen microbes resulting in no
additional microbial protein synthesis. In effect, fat is a by-pass energy sources for the lactating cow.
4. Added fats should be gradually increased in the ration allowing for palatability
changes (taste, odour, and form) and microbial adjustment, especially with unsaturated source. Remove fats gradually from the diet for similar reasons and allow for dry matter intake adjustments.
5. Limit the amount of supplement fat in early lactation (initial 3 to 5 weeks
NUTRIMIX BYPASS FAT:
By Pass Fat DENSE: Recommended to feed mixed with others ingredients. By Pass Fat HIGH: Can be feed mixed or direct feeding.
NUTRIMIX NZ Ltd. 2 WWW.nutrimix.co.nz / 0800-TOPMIX / [email protected]
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