Fat In Cattle Feed: What To Consider
Adding fat to dairy cow diets can help improve the energy balance of lactating dairy cows, thereby increasing fertility, milk production and other biological functions. But it must be carefully monitored.
Fat sources can be divided into two broad categories:
2. Commercial fat
In general, natural fats can be added to provide a 2-3% supplemental fat diet. The benefits of commercial fats become more pronounced when the total dietary fat content must exceed 5% of dietary DM. Commercial fat is important for its rumen inertia and is convenient for ease of handling. When comparing different commercial fats, consideration should be given to the price, availability and characteristics associated with palatability, inertness and digestibility. The amount of fat contained in the diet also depends on other ingredients in the diet (eg, high quality and low quality feed and the level of unsaturated fat contributed by the source).
How much is it?
Usually, 1% to 3% of supplemental fat in the diet can be fed without side effects, but this depends on the level of saturation of fat and fiber levels in the diet. The following equation can be used to calculate the amount of supplemental fat added to the diet based on fiber levels in the diet and unsaturated
FA (UFA) in fat sources (Jenkins, 1997): fat, %DM in diet = (4 x NDF) / UFA. Where UFA = the percentage of unsaturated fatty acids to total FA, NDF = neutral detergent fiber. For example, for a cow with 32% NDF and a diet considering baking soy, (4 x 32) / 85 = 128 / 85 = 1.5% fat from baked soybeans. However, since roasted soybeans contain about 20% fat, 7.5% of the diet can be roasted soybeans to provide 1.5% unsaturated fat in the soy diet.
Adding fat can improve reproductive parameters in different ways. Photo: Ton Kastermans
Impact on fertility
Adding fat can improve reproductive parameters in two ways. The first is to improve the energy status of the cow, and the other is the effect of fatty acids on the endocrine system. Adding fat to the cow's diet results in an increase in progesterone levels in the blood. Progesterone is synthesized by the corpus luteum and is responsible for the good implantation of the embryo in the uterus, helping to maintain the pregnancy and provide food for the embryo. When the diet is supplemented with fat, the increase in progesterone in the blood may be related to an increase in blood cholesterol and a larger follicle size. The FA curve of fat supplementation is important for its positive impact on fertility, and linoleic acid is one of the causes of FA. This has led to an increasing interest in the development of natural fat sources with higher levels of linoleic acid and calcium salts with higher levels of linoleic acid.
Impact on milk and methane
Fat-added diets generally increase milk production compared to control diets without added fat, although added fat can reduce DM intake, which can be compensated for by increased energy expenditure. In dairy cows, when the calcium fat of the encapsulated animal fat or palm oil FA is given and when the saturation is higher, the increased milk yield is greater. Adding fat to ruminant rations appears to be an effective and simple way to reduce methane production, thus reducing the negative impact of methane on energy efficiency. However, the effect of fat on methane production can vary depending on the source of fat and can be attributed to the biohydrogenation of unsaturated fatty acids in the rumen, promoting propionic acid production and preventing protozoal activity.
Used during lactation
Since fat does not seem to reduce weight loss during early lactation, and because some fats sometimes have palatability problems, it is recommended that you do not feed high levels of fat within 30 days of delivery. This strategy will allow cows to adapt to the lactation stage before fat is included in the diet. The main strategy for the first 2 to 4 weeks of lactation should be to maximize DM intake rather than energy intake. Energy intake can be a focus when intake levels reach acceptable levels. Early lactating dairy cows fed on a fat-supplemented diet may also develop ketosis (a metabolic disorder caused by excessive ketone concentration in the blood circulation due to fat burning energy). To avoid this problem, nutritionists recommend avoiding fats and fats in fresh cow diets because the cows are in a negative energy balance and remain "melted" in body fat, which will be "burned" to produce energy. Instead, the focus should be - to increase the intake of dry matter again.
Rapeseed oil is one of the natural sources of fat and can be used in animal feed. Photo: Shutterstock
From a rumen physiology point of view, cows are not prepared to handle fats and oils, at least in sufficient quantities to meet their high-yield milk requirements. The problem here is focused on unsaturated fats. Unsaturated fat is toxic to fiber-digesting bacteria. They also tend to cover fiber particles, thereby limiting the availability of fiber-digesting bacteria. The combination of the two has a negative impact on fiber digestibility, resulting in a decrease in rumen pH, leading to acidosis. It is best to exclude any and all fats and oils from the cow's diet, but this is impractical. A better approach is to allow each cow to receive no more than half a kilogram of fat per day from whole seeds (eg cottonseed, soybeans, rapeseed, etc.).Since the fat is gradually released during the rumination process, whole seed grinding is preferred.Another quarter of a kilogram of saturated fat (such as fats and fats) can be added to the above amount of fat, simply because saturated fat is often more expensive. If the opposite is true, you can feed up to three-quarters of a kilogram of saturated fat. It is highly unlikely that farms will deal with saturated fats because they require special equipment to keep them fluid, especially during cold times. Commercially available inert fat (highly saturated) can be used without worrying about the pH of the rumen. This fat is in the form of hydrogenated lipids, calcium soap and capsules. The only real negative factor is their high price, but when high-yielding cows are concerned, they usually offer value for money. In addition, they are a convenient form of drying, and each cow can feed up to half a kilogram per day, as well as the amount of other fats mentioned above.