Unseen Challenges in Balancing Fat in Poultry Nutrition
Published: July 7, 2020
By: Dr. Pooja Bhardwaj
Interesting facts
- The presence of fat in the diet inhibits the synthesis of fat from carbohydrates. The final composition of body fat is a pondered average among the fat produced endogenously from glucose, the quantity and composition of the fatty acids in the diet and the fat resulting from catabolism through b-oxidation (Ajuyah et al., 1991; Ferreira, 1999, Sanz et al., 2000b).
- Female broiler chickens tend to deposit more fat than male broiler chickens. Quantitative feed restriction for 10 days (beginning on the first day in the second week of age for female broiler chickens) led to a significant reduction in the abdominal fat % and total body fat deposition.
- Adding fat to feed as an isoenergetic substitution for carbohydrate usually results in an improved productive energy when the same level of MEn has been derived.
- Providing dietary fat decreases the need for hepatic fatty acid synthesis and generally increases yolk formation and the weight of the egg (Whitehead, 1981)
- During high environmental temperatures, as feed intake is reduced, the added fat permits hen to maintain egg formation while minimizing heat generation (Valencia et al.,1980).
- Replacement of tallow by vegetable fats rich in polyunsaturated fatty acids like sunflower oil, soybean oil, or linseed oil resulted in a decrease of abdominal fat deposition in broilers (Newman et al., 2002; Ferrini et al., 2008; Wongsuthavas et al., 2008).
- The apparent digestibility of the fat is high during the first week of age, low on the second and high after the third week of life.
Major goals of the poultry industry are to increase the carcass yield and to reduce carcass fatness, laying hens also exhibit excessive fat accumulation, which negatively affects their reproductive performance (Xing et al., 2009).
Benefits of fat inclusion in feed
Fat is the highest caloric value among all the nutrients, which adds “extra caloric” effect in the feed. Below are some benefits of including fat in poultry feed:
- Improves the absorption of fat-soluble vitamins.
- Decreases dustiness of feeds and reduced dust losses.
- Increases diet palatability.
- Reduces the rate of food passage through the gut, in turns better nutrient absorption.
- Lower heat increment during heat stress keeps caloric intake up.
- Concentrated feeds can decrease transportation costs for feed delivery.
Concerns with fat inclusion in feed
Concerns that should be noted with fat utilization:
- Use of higher levels of fat may negate the effects of pelleting
- Potential for rancidity
- Poor digestibility of saturated fats by the young bird
- Measurement of metabolizable energy (ME) content can be difficult
One of the major concerns related to fat usage is the actual ME value that should be assigned to each fat source. This number is often difficult to determine in a practical sense and may have little practical value in diet formulation. When analysing energy content of fat, it is generally done indirectly, by substitution of a portion of the ration fed in the ME determination. Additionally, fat may have an extra caloric effect (Jensen et al.,1970; Horani and Sell, 1977).
Fat additions resulted in digestibility of MBM being increased (Firman and Remus, 1994). This would explain why some ME values reported are greater than the gross energy values possible for fat as well.
Fat inclusion rate in feed
Each one percent addition of fat will add approximately 90 kcal of energy. Generally, broiler rations include fat at 1 to 3% in a starter ration and higher levels in the finisher.
Fat inclusion in feed revolve around the relative quality of the fat source and include rancidity, free fatty acid levels, and MIU (moisture, insoluble, & unsaponifiable).
Metabolically essential fatty acids (Linoleic acid & Linolenic acids)
Soybean oil is rich of Linoleic acid while Fish oil is rich of Linolenic acid. Inadequacies of linoleic acid are not readily encountered, but symptoms that result are due to a loss of membrane integrity. An increased need for water and decreased resistance to disease are characteristic deficiency symptoms observed in poultry (Balnave, 1970). A deficiency of linoleic acid in the male can impair spermatogenesis and affect fertility. Insufficient deposition of linoleic acid in the egg will adversely affect embryonic development. The essential fatty acid requirements of growing and adult birds can usually be satisfied by feeding a diet with 1 percent of linoleic acid. Higher levels of linoleic acid may be needed by the laying hen to achieve and maintain satisfactory egg weight.
Quality of fat
Oxidative rancidity occurs due to the oxidation of double bonds in unsaturated fatty acids, Decreases the nutritive value. Moreover, fat-soluble vitamins are destroyed by this process, especially vitamins A and E (Shermer, 1990).
Particularly oils and fats composed by unsaturated fatty acids suffer the attack of free radicals. Rancidity rapidly increased on the presence of catalysers such as other peroxides, copper, iron, nickel, cadmium, zinc, high temperatures and light.
Blending Effect
Blending of saturated fat with a small amount of vegetable oil is producing synergistic effect in absorption of saturated fatty acids. That’s why the resulting MEn value of blends is greater than the arithmetic calculation. (Ketels et al., 1986; Ketels and DeGroote, 1987).
TME for beef tallow was greater when a corn-based carrier was used durin measurement than when wheat was used. (Sibbald and Kramer; 1980).
Birds utilize unsaturated fatty acids more efficiently than saturated ones, especially at a young age.
Energy Correction measures
Some additives used in poultry diets to reduce the abdominal fat content.
- Reducing the energy level from 3,200 to 3,000 kcal/kg in broilers from 21 to 42 days significantly reduced the abdominal fat % & total body fat deposition without any negative effects on daily gain, feed intake or dressing %. (Kassim and Suwanpradit; 1996).
- L-methionine supplementation regulates the body fat content by reducing the activity of FAS (lipogenesis) and increasing the activity of hormone-sensitive lipase (HSL) (lipolysis). (Corzo et al.2006, Yao et al.2006, and Zhan et al.2006).
- Lysine improves meat quality (Lean meat) by enhancing muscle pH, increasing protein deposition, and reducing water-holding capacity.(Berri et al.2008; Tesseraud et al., 2009).
- 1% additional arginine above the NRC (1994) recommendations reduced the abdominal fat content and carcass fatness by decreasing the activities of malate dehydrogenase (MDH), G-6-PDH, and FAS (lipogenesis).
- Manganese (Mn) significantly reduced the carcass fatness by downregulating the activity of lipoprotein lipase (LPL) in the abdominal fat. (Klimis-Tavantzis et al., 1983).
- Inclusion of 1.5% conjugated linoleic acid (CLA) in broiler diets significantly reduced the abdominal fat & skin fat by downregulating peroxisome proliferator-activated receptor g (PPARg).Zhang et al; 2007, Royan et al; 2011).
- Betaine lowered the body fat content in broilers by increasing the activity of HSL and reducing the activities of FAS and LPL in the abdominal fat. (Wang et al.2004; Zhan et al;2006).
- L-Carnitine transports long-chain fatty acids across the inner mitochondrial membrane during beta-oxidation (the first step in fatty acid oxidation: catabolism), L-carnitine supplementation decreases abdominal fat deposition in meat-type poultry by reducing the activities of G-6-PDH, MDH (lipogenic enzymes). (Xu et al;2003).
- Polyphenols significantly reduced abdominal fat traits by inhibiting hepatic lipogenesis (Biswas and Wakit, 2001).
- Dihydropyridine (100 mg/kg)in broiler diets from 1 to 42 days of age was enough to suppress the activities of LPL in abdominal fat, as well as MDH and G-6-PDH in the liver, thereby reducing the abdominal fat percentage. (Niu et al; 2010).
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14 de julio de 2020
Alvaro Dubois, these considerations are pertinent and raise some important points to be considered with the use of fat in the diet of chickens exposed to a high temperature environment. There is a detail that I think deserves some more consideration. Regarding the use of fat, even in the condition in which the metabolizable energy of the feed is maintained, there must be an increase in the deposition of fat in the chicken carcass. This is related precisely to the fact that the fat for providing less caloric implement increases the net energy of the feed, and consequently can result in a greater amount of deposited fat. With regard to feed protein, the practice of reducing it in heat, using the concept of ideal protein, with industrial amino acid supplementation, also increases the net energy of the feed and may increase the concentration of fat in the carcass of birds. I agree with Dr Alvaro, that in hot conditions the responses of the chickens to nutritional changes are normally less expressive when compared to those of the chickens in thermoneutrality.
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Cargill
14 de julio de 2020
Dear Dr. Bhardwaj. It's an interesting review on potential fat benefits in poultry diets. I would like to raise some points here for further discussion, with particular regard to broilers. One is that is important to separate the impact of increasing fat addition with or without increasing energy in the diet. If we increase fat and energy, we will obtain fatter broilers with lower breast yield. In the case where broilers are cut up this will have a negative impact on sales revenues, not to mention potential complaints from consumers. If we increase energy and keep ideal protein to energy ratio the same to avoid it, then the benefit of increasing fat on heat generation is lost because protein has the opposite effect. On the other hand, the expected benefits on performances in broiler under heat stress might not be what we generally expect. For that, I refer to the meta-analysis published by Cerrate and Waldroup in 2010 in International Journal of Poultry Science (Maximum Profit Feed Formulation of broilers. 3. Interaction Between Energy Content and Temperature). They saw that responses to increases in energy were smaller for broilers under heat stress, especially for body weight gain (close to 50% of birds under thermoneutral conditions).
Also to reinforce Dr. Bhardwaj mention to the fact that when added in pelleted feeds (especially if added in the mixer) the negative impact on pellet quality can negate the expected benefits on weight gain and decrease the improvement in feed conversion. So, from an economical perspective, these negative points have to be considered in the calculations of expected benefit.
Thank you.
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14 de julio de 2020
In addition to what Professor Juarez said, that the addition of fat contributes to reduced heat production because it has a lower heat increment than protein or carbohydrates, the addition of fat increases the energy value of the other feed ingredients in the diet. It has also been shown that fat decreases the rate of food passage in the GI tract and thus increase nutrient utilization. Because of all these findings, the addition of fat is beneficial at high temperatures.
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10 de julio de 2020
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Dr Pooja Bhardwaj, my compliments for the quality of the reviewed subject. Taking the opportunity of the matter, I would like to make a consideration about the use of fat in the diet of chickens exposed to high temperature environment. One of the fundamentals of nutrition is that increasing the concentration of dietary energy leads to a reduction in voluntary food consumption by birds. If at high temperature there is a natural reduction in consumption, what would be the basis for increasing its concentration under these conditions. It is that in high temperature conditions, different from those of the thermoneutral, for the voluntary food intake by the birds to be reduced, it is necessary that the increase in energy be much more expressive. Thus revealing that the physiology of birds is altered by temperature. Thus, it can be deduced that the negative influence of high temperature on the performance of birds is not justified simply by reducing food consumption. The advantage of using fat as an energy source in these conditions is actually its lower caloric increase
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14 de julio de 2020
Dr Pooja Bhardwaj Thank you very much for the informative article.
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