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The early nutrition of broilers is becoming more important as knowledge about the positive correlation between the early growth rate and market weight increases, as well as the impact of early growth on the development of weight uniformity and in the composition of the carcass.
All these factors are even more critical in antibiotic-free production systems -ABF.
The optimization of early digestion is often the key to a successful farm program, since it is the best tool to prevent dysbacteriosis, coccidiosis and necrotic enteritis. Early weaned pigs face similar challenges, especially in ABF pig production systems. One of the key universal ingredients in pig-weaning diets is spray-dried plasma -SDP- which is not only a highly digestible protein source, but a functional protein source.
Certainly, it would be interesting to know and study the potential benefits associated with the inclusion of plasma in pre-initiation diets of broilers in ABF systems.
The optimization of early digestion is the key to a successful farm program
Plasma is collected during pig slaughter, and is normally separated from red cells by centrifugation.
The biggest difference between the various plasma products on the market and blood meal is the separation of the plasma from the red cells as well as the lower temperatures and times applied in spray drying of the plasma.
SDP -spray-dried plasma results in a free-flowing flour composed of 75-80% crude protein, minerals and about 8% residual water. Approximately 95% of the proteins are albumins and globulins (Tumbleson et al, 1986). The amino acid profile of the SDP is shown in Table 1.
Table 1. Nutritional Content of SDP * Total sulfurized amino acids, ** Apparent Metabolizable Energy
Essential amino acids represent 40% of total proteins. The main amino acid deficiencies related to lysine content are TSAA and isoleucine.
Although that amino acid profile is significant in the formulation from an economic point of view, its mere contribution cannot explain the positive effect seen in piglets when replacing fishmeal with SDP.
The benefit of SDP in neonates is possibly associated with the fact that their amino acids are part of the functional proteins that impart greater advantages in newly weaned pigs, and in young chickens. The immunoglobulins present in the SDP can be separated into high, medium and low fractions in terms of molecular weight, corresponding to globulins, albumins and fibrin, respectively.
The spray-dried plasma is composed of 75-80% protein
The IgG molecule cannot be absorbed intact, so it is assumed that the beneficial effects of these globulins occur in the small intestine. It is assumed that globulins arrive intact in the small intestine and bind to bacteria and viruses preventing their proliferation.
In piglets, the use of SDP -spray-dried plasma – has been shown to increase the elimination rate of certain intestinal and respiratory viruses. There is improvement in the function of the intestinal barrier, less cellular inflammation and less diarrhea and indigestion.
There are also some glycoproteins in the SDP -spray-dried plasma that have adhesion sites for the fimbriae of E. Coli.
They also stimulate the proliferation of lactobacillus species, so in general, they promote an advantageous microbiota.
The most important benefits observed are attributed to the increase in the growth of intestinal microvilli in relation to the depth of the crypts, effects similar to those observed with the use of antibiotics.
The benefits observed in health and production are due to a lower production of pro-inflammatory cytokines, which entails a process that demands a lot of energy and therefore a lower production of these pro-inflammatory cytokines allows redistributing energy to productive functions in the animal.
Therefore, feeding with SDP -spray-dried plasma- probably has more effect on NE-net energy- than on AME-apparent metabolizable energy-, although the latter would simply be improved by a better intestinal development with absence of diarrhea. One of the final impacts of SDP on nutrient absorption in general would be the reduction of amino acid catabolism by the intestinal microbiota.
There are many interesting similarities between the challenges of newly weaned pigs and newborn chickens, especially in ABF systems.
Both types of animals face a sudden change in the type of feeding, the challenges arising from the mixing of populations, the stress of process and transport, and the low contribution of maternal antibodies in relation to the challenge caused by environmental microbes and enterotoxins present in the feed. While chicken weight can vary between 10-15%, the weight of newborn pigs can vary between 50-80%.
In general, at least a 20% increase in pig growth can be expected in the first 7-14 days after weaning when fed with moderate amounts of SDP, even if specialized diets contain quality animal proteins such as milk and fishmeal.
One of the biggest current challenges in both pig and broiler production systems is the variability in the final body weight.
While many feed options and/or additives can increase the average yield of the lot, there is usually little impact on the variation in weight. It is increasingly evident that such variation in chicken weight of 2-4 kg is probably greatly influenced by early development. The genetic selection has allowed in the breeders the increase of the production of eggs that is associated to a greater variation in the weight of the egg and in the weight of the chick when leaving the hatchery.
Since each gram of body weight in broilers at 7 days is equivalent to 10 g of difference in weight at 40 days, there is great potential for studies with SDP -spray-dried plasma- in pre-initiating diets, both to standardize, as to improve the growth rate.
It has been suggested that such early variation in body weight may be due to transient anorexia (12-24 hours) in chicks due to lack of intake during the first 24-36 hours. After the period of anorexia, the animal usually eats until it is satisfied to compensate, but unfortunately this situation occurs at a time when there is no production of endogenous enzymes.
The resulting indigestion can promote the breakdown of the balance of the intestinal microflora and therefore the need for products such as SDP that support intestinal health and immune response.
After anorexia, the chicks eat until they are satisfied but at a time when there is no production of endogenous enzymes, causing indigestion and a breakdown in the balance of intestinal flora
The main challenges of ABF production are intestinal dysbacteriosis, coccidiosis and subsequently necrotic enteritis. While this cascade of events culminates with an observable risk or danger in the bird between 15-20 days of age, the underlying cause may be an indigestion in the first days of age.
Summarizing the results of different studies in broilers, they suggest that improvements in the pre-initiation period were 4% in ADG (Average Daily Gain) and 2.6% in F : G (Feed Consumption: Gain).
Since the functional proteins of the SDP – spray-dried plasma – are more susceptible to the heating process than other proteins are, we can consider the effectiveness of the use of SDP in modern food manufacturing processes. Campbell et al. 2006 showed the resistance of the SDP to different granulation conditions and even in expanded feed produced up to 149°C – Graph 1-.
Graph 1. Body Weight (g) of broilers fed SDP-containing diets processed at high temperatures
The most obvious benefits derived from the use of SDP in broiler diets are observed when animals suffer a natural or artificial infection with various pathogens
Campbell et al. (2006) evaluated the use of SDP in chickens that naturally suffered a severe necrotic enteritis infection confirmed by the veterinarian. In the study, the birds were fed either continuously with SDP (1% on days 1-14, 0.5% on days 15-28 and 0.25% on days 29-35), or discontinuously (1% SDP on days 1-14). The diet with SDP had a clear reduction in mortality due to necrotic enteritis. Poultry fed with SDP discontinuously remained protected after day 14, although from that day they consumed a control diet without SDP supplementation. -Graphs 2 and 3-.
Graph 2. Survival of broilers fed with plasma during a natural outbreak of Necrotic Enteritis
Graph 3. Average daily consumption of feed in broilers fed with plasma during a natural outbreak of Necrotic Enteritis
The use of SDP not only had a positive impact on survival, but also on food consumption. The positive effect of the SDP could be associated with the maintenance of a better structure and integrity of the intestinal villi, together with the ability of the SDP to fight pathogens
The widely accepted practice of including spray-dried plasma in weaning diets for pigs is based on the ability of the product to deliver functional proteins that drive growth and efficiency as they normalize or improve bowel function. Plasma-fed piglets are consistently healthier and show less diarrhea, so they have more ability to use the full spectrum of dietary nutrients.
We can learn from this application of the SDP for use in pre-starters in broilers and particularly in situations where birds develop with minimal pharmacological support. Recent research shows a favorable response in broilers fed with SDP that are likely to guarantee a future role in our arsenal of “antibiotic alternatives”.
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