Rendered Animal Protein Research Articles

92 Implications of Processing and Handling on the Functionality of Animal Derived Products for Pet Foods

Abstract The pet food industry has been closely tied to the livestock, meat, and rendering industries by using materials left over from human food production. Rendered animal fats are an excellent source of dietary fat and provide enhanced palatability when used to enrobe dry pet food. Mechanically deboned meat, viscera, and rendered protein meals are often utilized as a primary source of highly digestible, well-balanced proteins and vitamins and minerals. Although these products can be easily transported and stored, they are susceptible to oxidative and microbial degradation. Antioxidants and antimicrobials aid in preserving the quality of these ingredients but are only part of the solution. How these ingredients are produced, stored, and handled can impact quality. It is important to remember that this raw material stream starts with livestock management practices. Specifically, changes in nutritional practices in the livestock industry can impact the characteristics of the products used for both human and pet foods, especially when considering poultry and pork products. Demands by consumers in the meat industry have resulted in the popularity of vegetarian diets. For example, decreased amounts of rendered animal protein meals in diets fed to chickens and turkeys have shifted towards more unsaturated fats, ultimately decreasing oxidative stability. Handling animal products throughout their supply chain can also affect product quality and potential usability. After harvest, raw material is often transported and processed by two or more different facilities before arriving at the pet food manufacturer. At the meat and rendering facilities, food safety hurdles along with processing aids can limit biogenic amine or free fatty acid formation. Once oxidation and microbial degradation occur, they cannot be reversed. Therefore, addressing food safety or oxidation control upstream in the supply chain is critical. Since each facility is unique in how co-products are processed and handled, understanding how different antioxidant blends and how and where these are applied all impact final product quality; this carries through to the quality and shelf life of the pet food diet these ingredients are intended for. With most pet foods targeting 18 months to 2 years of shelf life, starting with high-quality ingredients is key to achieving these goals. The human food, rendering, and pet food industries remain closely tied together. Trends within the meat and rendering industry result in the potential for these ingredients to be more susceptible to quality and functionality changes. The pet food industry must continue to monitor and evaluate changes in livestock production practices and product handling. Proactive management of these ingredients throughout the supply chain can ensure that these ingredients remain high-quality, cost-effective ingredients for pet food.

Effects of replacing fish meal with rendered animal protein blend on growth performance, hepatic steatosis and immune status in hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂)

An 8-week growth trial was conducted to evaluate the effects of substitution of fish meal (FM) by rendered animal protein blend (APB) consisting of poultry by-product meal (PBM), shrimp meal (SM) and spray-dried blood meal (BM) in diets of juvenile hybrid grouper, Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂ (32.51 ± 0.31 g). A basal diet (FM70) with FM as the sole protein source was compared to diets progressively replacing 20% (FM56), 40% (FM42), 60% (FM28) and 80% (FM14) of FM protein. No significant differences were found in final body weight (FBW) and weight gain (WG) of fish when up to 80% of FM protein was replaced by APB. The feed efficiency (FE) and protein efficiency ratio (PER) were markedly decreased when dietary APB inclusion levels exceeded 40%. The heaptosomatic index (HSI) and whole body crude lipid content increased as dietary APB levels increased. Plasma cholesterol (CHO), high-density lipoprotein cholesterol (HDLC) and low-density lipoprotein cholesterol (LDL-C) contents of fish fed the APB containing diets were higher than the control group. Liver histological analysis showed the amounts of hepatic vacuoles and lipid droplets were significantly increased as dietary APB levels increased, which is a sign of hepatic steatosis. Moreover, dietary APB inclusion up-regulated the mRNA levels of lipid metabolism-related genes including peroxisome proliferator-activated receptor alpha (PPARα), carnitine palmitoyltransferase 1 (CPT1), fatty acid synthase (FAS) and apolipoprotein AI (Apo-AI) while down-regulated lipoprotein lipase (LPL) levels. On the other hand, dietary APB inclusion also up-regulated the apoptosis-related genes including caspase-3, caspase-8, caspase-9 and p53 as well as inflammation-related genes including interleukin 8 (IL-8), interleukin 10 (IL-10) and transforming growth factor β1 (TGF-β1) in the liver of hybrid grouper. In conclusion, up to 80% FM can be replaced by APB protein in diets for hybrid grouper juveniles without compromising growth performance, and high levels of dietary APB could induce hepatic steatosis and thus impair the immune status of hybrid grouper.

Effect of Total Fish Meal Replacement with Vegetal Protein Alone or Combined with Rendered Animal Protein on Growth Performance and Tissue Composition of European Catfish (Silurus glanis L.)

A feeding trial was conducted for six weeks to determine the effect of the replacement of fishmeal (FM) either with vegetal protein (mainly soybean) and rendered animal protein combined or vegetal protein alone on growth and carcass composition of European catfish, Silurus glanis. One hundred and thirty five fish (average weight 70.90±5.10g ±SD) were randomly distributed into three treatments in triplicate. Fish were fed with either of three isonitrogenous (35% crude protein) and isocaloric (16.70 MJ/kg DE) experimental diets. The diets were: fish meal (FM) based diet, fish meal protein replaced with a combination of vegetal protein and rendered animal protein (AP), and fish meal replaced with vegetal protein only (SM). Weight gain (%), specific growth rate, protein efficiency ratio, and apparent net protein utilization of FM diet fed groups were similar (P>0.05) with AP diet fed group being significantly higher (P < 0.05) than the SM group. Feed conversion ratio with FM diet was similar (P < 0.05) to that of the AP diet, and significantly lower than SM diet. The present experiment indicated that vegetal protein alone cannot replace total FM protein in the diet of Silurus glanis, however, vegetal protein and rendered animal protein combined, can replace total fish meal protein, with no detrimental effect on growth performance, feed utilization, and body composition.

Effects of fish meal replacement with animal protein blend on growth performance, nutrient digestibility and body composition of juvenile Chinese soft-shelled turtlePelodiscus sinensis

An 8-week feeding trial was conducted to evaluate the potential of partial replacement of fish meal with rendered animal protein blend (APB) [meat and bone meal (MBM): expanding blood meal (EBM) = 4 : 1] in the diet of juvenile Chinese soft-shelled turtle Pelodiscus sinensis. Seven isonitrogenous and isoenergetic practical diets replacing 0%, 10%, 20%, 30%, 40%, 50% and 60% fish meal protein by APB were formulated. Weight gain, feed efficiency, protein efficiency and the apparent digestibility coefficients (ADCs) of dry matter and gross energy in the experimental diets all exhibited no significant difference (P > 0.05) when dietary fish meal was replaced for 0–40%, but decreased significantly (P 0.05) among all the treatments. Nitrogen retention and the ADCs of protein and most amino acids all decreased significantly (P < 0.05) when fish meal was substituted by more than 30%. The results indicated that fish meal in the practical diet of juvenile Chinese soft-shelled turtle could be replaced by 30–40% using a combination of MBM and EBM without negative effects on growth performance, nutrients digestibility and body composition.

Effects of replacing fish meal with rendered animal protein and plant protein sources on growth response, biological indices, and amino acid availability for rainbow trout Oncorhynchus mykiss

Duplicate groups of rainbow trout (mean initial weight 16.7 ± 0.1 g) were fed six isonitrogenous (43.7 % crude protein) diets for 12 weeks. A fish-meal-based diet was designated the control. In the other five diets, 75 or 100 % of the fish meal was replaced with either poultry by-product meal (PBM), hydrolyzed feather meal (FEM), and spray-dried blood meal (BM) or with defatted soybean meal and corn gluten meal. Trout fed the diets in which 75 and 100 % of the fish meal was replaced with rendered animal protein showed comparable growth performance to trout fed the control diet except in terms of the protein efficiency ratio and feed conversion ratio. The feed intake of the trout fed a combination of fish meal and rendered animal protein (either with or without plant protein) was significantly higher than the feed intake of trout on the fish-meal-based diet. Apparent crude protein digestibility coefficients were significantly higher in trout fed the diets in which 75 % of the fish meal was replaced with plant protein sources than in trout fed the diets in which 75 % of the fish meal was replaced with rendered animal protein sources (P < 0.05). These results suggest that a combination of PBM, FEM, and BM is a good substitute for most of the fish meal in practical feed for rainbow trout.

Performance, body compositions, input and output of nitrogen and phosphorus in Siberian sturgeon, Acipenser baerii Brandt, as affected by dietary animal protein blend replacing fishmeal and protein levels

An 8-week growth trial was conducted using a 2 × 3 factorial design to evaluate the effect of substitution of fishmeal (FM) by rendered animal protein blend [APB, comprised of 400 g kg−1 poultry by-product meal, 350 g kg−1 meat and bone meal, 200 g kg−1 hydrolysed feather meal (HFM) and 50 g kg−1 spray-dried blood meal] in diets of Siberian sturgeon, Acipenser baerii Brandt. Two isoenergetic control diets were formulated to contain two different protein levels [high-protein control (400 g kg−1), with 483 g kg−1 of FM] and [low-protein control (360 g kg−1), with 400 g kg−1 of FM]. At each protein level, dietary FM protein was replaced by APB at 75% and 100% levels and supplemented with crystallized essential amino acid under ideal protein concept. The six diets were named as HC, HAPB75, HAPB100, LC, LAPB75 and LAPB100, respectively. No significant differences were found in weight gain rate (WGR) and specific growth rate (SGR), but fish fed with the low-protein diets showed higher feed intake and feed conversion ratio. Plasma growth hormone and insulin-like growth factors I of each group were not significantly different (P > 0.05). The whole-body composition and liver composition were not affected by dietary protein levels, replacement or their interaction. Muscle protein and lipid contents of fish fed with diet LAPB100 were significantly lower than those of HC group. Digestibility of nitrogen (N) and phosphorus (P) were reduced with higher APB inclusion levels, but productive N and P values of all groups were not different. Lower N and P intake induced lower nutrients losses (P < 0.05). The results suggested that dietary protein level could be reduced to 360 g kg−1 from 400 g kg−1 without affecting WGR or SGR and significantly reduced nutrients lose. Furthermore, dietary FM protein can be totally replaced by APB in feed formulation either at 400 g kg−1 or at 360 g kg−1 protein level.

Nonfeed Application of Rendered Animal Proteins for Microbial Production of Eicosapentaenoic Acid by the Fungus Pythium irregulare

Rendered animal proteins are well suited for animal nutrition applications, but the market is maturing, and there is a need to develop new uses for these products. The objective of this study is to explore the possibility of using animal proteins as a nutrient source for microbial production of omega-3 polyunsaturated fatty acids by the microalga Schizochytrium limacinum and the fungus Pythium irregulare. To be absorbed by the microorganisms, the proteins needed to be hydrolyzed into small peptides and free amino acids. The utility of the protein hydrolysates for microorganisms depended on the hydrolysis method used and the type of microorganism. The enzymatic hydrolysates supported better cell growth performance than the alkali hydrolysates did. P. irregulare displayed better overall growth performance on the experimental hydrolysates compared to S. limacinum. When P. irregulare was grown in medium containing 10 g/L enzymatic hydrolysate derived from meat and bone meal or feather meal, the performance of cell growth, lipid synthesis, and omega-3 fatty acid production was comparable to the that of culture using commercial yeast extract. The fungal biomass derived from the animal proteins had 26-29% lipid, 32-34% protein, 34-39% carbohydrate, and <2% ash content. The results show that it is possible to develop a nonfeed application for rendered animal protein by hydrolysis of the protein and feeding to industrial microorganisms which can produce omega-3 fatty acids for making omega-3-fortified foods or feeds.

Replacement of fish meal with blend of rendered animal protein in diets for Siberian sturgeon (Acipenser baerii Brandt), results in performance equal to fish meal fed fish

An 8w growth trial was conducted to determine the effect of partial replacement of fish meal (FM) by a blend of rendered animal protein (BAP, comprised of 40% meat and bone meal, 40% poultry by-product meal, 20% hydrolyzed feather meal in diets for juvenile Siberia sturgeon (Acipenser baerii Brandt). Five experimental diets were formulated. The control diet (C) contained 48% FM, whereas in the remaining four diets, FM were replaced by BAP at 25% or 50% level balanced by crystallized amino acid (AA) or spray-dried blood meal (BM), which named as BAP25-AA, BAP25-BM, BAP50-AA and BAP50-BM, respectively. Weight gain rate of BAP50-AA group was significantly higher than that of C group, while other BAP diets did not show negative effect on growth performance. The BAP25-BM group exhibited the lowest feed conversion rate (FCR) (P < 0.05). FM replacement by BAP did not affect chemical composition of the whole body and crude fat level of the liver, but significantly affect the fillet lipid content. Hepatic aspartate aminotransferase and serum total protein, total cholesterol and triglyceride were reduced in fish fed diet BAP50B. Siberian sturgeon showed high efficiency on utilization of crystalline amino acid as good as those from BM.

Soybean Meal and Rendered Animal Protein Ingredients Replace Fishmeal in Practical Diets for Sea Bass

A 180-day feeding trial was carried out in net cages to examine replacement of fishmeal with soybean meal supported by meat/bone meal and blood meal in practical diets for sea bass (Dicentrarchus labrax L. 1758). Triplicate groups of fish (initial body weight 110 g) were fed one of four isonitrogeneus (crude protein 46%) and isolipidic (10%) diets. A commercial sea bass diet containing 64% fishmeal as the sole animal protein served as the control. The other three diets contained 0, 20%, or 35% fishmeal and the reduced fishmeal was replaced by different levels of soybean meal, meat/bone meal, and blood meal. The final body weight of fish fed the diet containing 20% fishmeal, 50% soybean meal, 10% meat/bone meal, and 4% blood meal was significantly higher than that of the other three treatments. Results indicate that fishmeal can be reduced to 20% when soybean meal, meat/bone meal, and blood meal are used together in the diet.

Bovine spongiform encephalopathy risk management in Australia and New Zealand

Between 1962 and 1966, Australia and New Zealand ceased importing rendered animal protein from any country other than each other; as a result, both were protected against bovine spongiform encephalopathy (BSE) contaminated meat and bone meal (MBM), which was being exported from the UK during the 1980s. More recently, global trade considerations have encouraged these countries to relax their import restrictions to some extent, while at the same time requiring convincing evidence that appropriate steps are being taken domestically to control mad cow disease. Both countries have successfully maintained their 'BSE-free' status. However, whereas Australia has retained more stringent policies with respect to BSE risk, New Zealand has adopted policies compatible with trade liberalisation.

Composition, Properties and Sensory Quality of Rainbow Trout Affected by Feed Formulations

Abstract Rainbow trout were fed a fish meal‐based diet or diets where 25, 50, 75, or 100% of the fish meal protein was replaced with a mixture of rendered animal protein ingredients. Diets were formulated to be iso‐nitrogenous (36% crude protein) and meet all known nutrient requirements of rainbow trout. The effect of five diets on dressing percentage, chemical composition, functional properties, and sensory characteristics of rainbow trout fillets stored up to 1 wk on ice in a refrigerated room (4 C) was determined. Dressing percentage based on body weight (from 724 to 811 g) did not show a significant difference due to the diet. Raw tissue pH, 24 and 144 h post mortem, were significantly lower than the control when 75 and 100% fish meal replacement were utilized. Assessment of color, texture, flavor, and tenderness indicated that fillet were lighter, less firm, more bland, and more tender after 144 h compared to 24‐h storage time. Fillets from fish fed all diets were considered as acceptable by the panel.

High dietary incorporation levels of rendered animal protein ingredients on performance of rainbow trout Oncorhynchus mykiss (Walbaum, 1972)

Two growth trials were conducted using spray-dried blood meal (BM), feather meal (FEM), meat and bone meal (MBM) and poultry by-product meal (PBM) as major protein sources in the diet of rainbow trout. In the first trial, five diets were formulated to examine the nutritive value of spray-dried BM and PBM. Increasing levels of BM (6, 12%) or PBM (10, 20, and 30%) replaced fish meal and corn gluten meal in the diet. For the second trial, eight diets were formulated to contain the following combinations: FEM + MBM, FEM + PBM or MBM + PBM. The diets containing FEM + MBM and FEM + PBM were supplemented with either L-lysine or DL-methionine, the amino acids predicted to be the two most limiting in these diets. Each experimental diet was allocated to three tanks of fish and fed for 20 weeks in the first trial or 16 weeks in the second trial. All the experimental diets were readily consumed by the fish and high growth and good feed efficiency ratio (FER) were achieved for all diets. In the first trial, there were no significant differences ( P > 0.05) in weight gain or FER of fish fed the five experimental diets, suggesting that BM and PBM had high nutritive values for rainbow trout. In the second trial, growth of the fish fed the diet containing the FEM + PBM combination was not statistically different from growth of fish fed the control diet. Growth of fish fed diets with FEM + MBM or PBM + MBM combinations were slightly lower than that of fish fed the control diet. Supplementation of diets with either L-lysine or DL-methionine had no effect on the performance of the fish. The results from this study show that feather meal, poultry by-product meal, blood meal and meat and bone meal have good potential for use in rainbow trout diets at high levels of incorporation.

Replacing Fish Meal with Rendered Animal Protein Ingredients in Diets for Malabar Grouper, Epinephelus malabaricus, Reared in Net Pens

Abstract The potential of using rendered animal protein ingredients, poultry by‐products meal (PBM), meat and bone meal (MBM), and feather meal (FM), to replace fish meal in diets for malabar grouper, Epinephelus malabaricus, was evaluated in a 10‐week net pen experiment. Triplicate groups of fish (initial body weight 50.2 g) were fed eight isonitrogenous and isocaloric diets formulated to contain 52% crude protein and 9% crude lipid. The control diet contained 50% herring meal, whereas in the remaining seven diets, PBM was incorporated at 11.9 (PM1), 23.8 (PM2), and 35.7% (PM3) to replace 25, 50, and 75% of the fish meal; MBM was incorporated at 14.5 (MM1) and 29.0% (MM2) to replace 25 and 50% of the fish meal; and FM was incorporated at 9.4 (FM1) and 18.8% (FM2) to replace 25 and 50% of the fish meal. A raw fish (RF) diet was used as comparison to assess growth performance of fish fed the formulated diets. Feed intake was lower in fish fed the diets PM3 and FM2 than fish fed the control diet. There were no significant differences in weight gain (WG), final body weight (FBW), nitrogen retention efficiency (NRE), energy retention efficiency (ERE), and total nitrogen waste output (TNW) between fish fed the control diet and the diets PM1, PM2, PM3, MM1, MM2, and FM1. Fish fed the diet FM2 had lower WG, FBW, NRE, and ERE but higher TNW than that of fish fed the control diet. Feed conversion ratio (FCR) was higher in fish fed the diets MM2, FM1, and FM2 than fish fed the control diet. At the end of the experiment, there were no significant differences in whole‐body content of moisture, crude protein, and crude lipid among fish fed the formulated diets. WG, FBW, and TNW of fish fed the diet RF were higher, while FCR and NRE were lower than that of fish fed the control diet. No significant differences were found in feed intake, ERE, and whole‐body composition between fish fed the diet RF and the control diet. Results of the present study suggest that dietary fish meal level for malabar grouper can be lowered from 50 to 38% by incorporating PBM, MBM, or FM.

Replacement of fish meal by rendered animal protein ingredients with lysine and methionine supplementation to practical diets for gibel carp, Carassius auratus gibelio

The effect of partial replacement of fish meal (FM) by rendered animal protein ingredients: poultry by-product meal (PBM) and meat and bone meal (MBM), alone or in combination, with lysine and methionine supplementation in the practical diets for gibel carp was studied. Eight isonitrogenous (crude protein 37.5%) and isolipidic (crude lipid 7%) diets were formulated to feed juvenile gibel carp (initial body weight 13.45±0.04 g fish−1) for 12 weeks. Diet 1 (control) was a high quality commercial gibel carp diet, containing 18% FM as the sole animal protein source without amino acids (AAs) supplementation. In the other seven diets (Diets 2–8), 33.3–100% of FM protein was replaced by PBM, or a blend of PBM and MBM. Lysine (Lys) and methionine (Met) were supplemented to Diets 2–8 in order to match the AAs profile of the control diet. The results showed a significant difference in final individual body weight (FBW) and specific growth rates (SGR) among fish groups (P<0.05). Fish fed the test groups showed no significant difference compared with the control group except for fish fed Diet 8. The highest FBM and SGR were recorded in fish fed Diet 5, which contained the combination of 9% PBM and 4.5% MBM to replace 67% FM protein with Lys and Met supplementation. Carcass composition, CF, HSI and VSI among all groups at the end of the experiment were not significantly affected by the dietary treatments. The optimal replacement level of FM by the combination of PBM and MBM, with Lys and Met supplementation, was shown by third-order polynomial regression analysis to be 66.7% in protein.

Inclusion of rendered animal ingredients as fishmeal substitutes in practical diets for cuneate drum, Nibea miichthioides (Chu, Lo et Wu)

Potential of using rendered animal ingredients, poultry by-product meal (PM), meat and bone meal (MBM), feather meal (FM) and blood meal (BM) to replace fishmeal in practical diets for cuneate drum Nibea miichthioides (Chu, Lo et Wu) was examined in a net pen experiment. A total of 10 dietary treatments were compared. Nine diets were formulated to contain 363 g kg−1 digestible protein and 14.8 MJ kg−1 digestible energy, and a dietary treatment consisting of raw fish (RF) served as reference. In the formulated diets, the control diet contained 350 g kg−1 herring meal, whereas in the other eight diets, the fishmeal were replaced by MBM (30% fishmeal replacement), PM (50% fishmeal replacement), a blend of PM, MBM, FM and BM (30%, 50% and 80% fishmeal replacement), or a blend of PM, MBM and BM (30%, 50% and 80% fishmeal replacement), respectively. Cuneate drum fingerling (initial body weight 28 g) were fed the test diets for 8 weeks. Specific growth rate (SGR), final body weight (FBW), nitrogen retention efficiency (NRE), condition factor and contents of moisture, crude protein and crude lipid in carcass were not significantly different between fish fed the formulated diets. Fish fed the formulated control diet exhibited lower SGR and FBW, but higher FCR, NRE, hepatosomatic index and crude lipid content in carcass and liver than those of the fish fed the RF. Results of the present study indicate that combination of rendered animal protein ingredients can replace most of the fishmeal in practical diets for cuneate drum.

Performance and sensory evaluation of silver perch (Bidyanus bidyanus Mitchell) fed soybean or meat meal-based diets in earthen ponds

The performance of silver perch fed a commercially available diet based on meat meal (38%), grain legumes (18%), oilseeds (10%), wheat millrun (20%), fishmeal (5%) and fish oil (3%) was compared with experimental diets based on alternative protein sources in two experiments. In Experiment 1, two experimental diets contained similar contents of fishmeal and fish oil as the commercially available reference diet, but soybean (25%) and wheat millrun (>31%) were used to reduce animal protein meals by approximately 50%. The digestible protein and digestible energy of the two experimental diets was either slightly lower (31.5% and 12.8 MJ kg−1) or slightly higher (34.9% and 14.3 MJ kg−1) than the reference diet (32.1% and 13.2 MJ kg−1). In Experiment 2, the two experimental diets contained no fishmeal but included higher amounts of rendered animal meals (41–48%). One of the diets had similar digestible protein to the reference diet (32%) while the other had only 25% digestible protein. Silver perch (38 g for Experiment 1 and 59 g for Experiment 2) were stocked into each of nine 0.1 ha earthen ponds with fish in three ponds fed each diet for 191 days (Experiment 1) or 187 days (Experiment 2). Survival was >94% in all ponds in both experiments. In Experiment 1, growth rates and feed conversion ratios (FCRs) ranged from 2.1 to 2.4 g fish−1 day−1 and 1.7 to 1.9 respectively. Growth rates were significantly (P 0.05). In Experiment 2, growth rates and FCRs ranged from 2.3 to 2.4 g fish−1 day−1 and 1.6 to 1.7. There were no significant differences in fish performance indices for any of the three diets although experimental power was low (power=0.31). A blind consumer sensory evaluation (taste panel) of fish fed the three diets in Experiment 2 rated fish as ‘highly acceptable’. The diet with the lowest digestible protein content produced the best fish in terms of ‘smell liking’, ‘flavour liking’, ‘muddy flavour strength’ and ‘fresh flavour strength’. These results confirm that soybean meal and/or rendered animal protein ingredients including meat meal and poultry offal meal, and wheat can form the basis for high-performance, low-cost diets for intensive pond culture of silver perch.

Replacement of fish meal by rendered animal protein ingredients in feeds for cuneate drum ( Nibea miichthioides)

An 8-week feeding trial was carried out in floating net pens to examine the replacement of fish meal with three rendered animal protein ingredients, poultry by-product meal (PBM), meat and bone meal (MBM) and feather meal (FM) at various levels in practical feeds for cuneate drum. Triplicate groups of fish (initial body weight 27 g fish − 1) were fed nine isonitrogenous and isocaloric feeds formulated to contain 36% digestible protein and 15 MJ kg − 1 digestible energy. The control feed contained 35% herring meal, whereas in the other eight feeds, PBM, MBM and FM, alone or in combination, directly replaced 10%, 30% or 50% of the fish meal. In addition, a raw fish feed was used as a comparison to assess growth performance of fish fed the formulated feeds. There were no significant differences in feed intake and feed conversion ratio (FCR) among fish fed the formulated feeds. Specific growth rate (SGR) and final body weight (FBW) of fish fed the feeds in which either PBM replaced 30% to 50 % of the fish meal or MBM replaced 30% of the fish meal were not significantly different from fish fed the control feed. Feather meal incorporation in the feeds resulted in lower SGR and FBW compared to those of fish fed the control feed. Replacing 50% of the fish meal by MBM significantly lowered SGR, FBW and nitrogen retention efficiency, whereas replacing 50% of the fish meal by a combination of PBM, MBM, FM, blood meal and soybean meal resulted in lower SGR and FBW. There were no significant differences in chemical composition of whole body among fish fed the formulated feeds. Results of the present study indicate that PBM can be used alone at 17% (to replace 50% of the fish meal), and MBM at 10% (to replace 30% of the fish meal) in feeds for cuneate drum.

Comparative utilization of rendered animal derived products with or without composite mixture of soybean meal in hybrid tilapia ( Oreochromis niloticus × Oreochromis mossambicus) diets

The utilization potential of some rendered animal protein derived products as partial replacement for high grade fish meal protein in practical diets for hybrid tilapia was investigated in two successive laboratory feeding trials. In trial 1, rendered animal protein sources, poultry by-product meal (PBM), hydrolyzed feather meal (HFM), enzyme treated feather meal (EFM) and blood meal (BM) were used to partially replace high grade low temperature Norwegian fish meal (LT-94) at 66% dietary inclusion for juvenile tilapia in an experiment that lasted for 70 days. In trial 2, the effects of hydrolyzed or enzyme treated feather meals with or without composite mixture of soybean meal as partial replacement for low temperature fish meal in diets for hybrid tilapia fingerlings was investigated for 56 days. Trials 1 and 2 comprising five diets in triplicate treatments each were made isonitrogenous at 30% and 35% crude protein while energy levels of diets were isocaloric at 8% and 12% lipid for juveniles and fingerlings of hybrid tilapia, respectively. The results of trial 1 showed that fish fed poultry by-product meal (PBM) had the best productivity values of weight gain, feed conversion ratio, specific growth rate and protein efficiency which were not significantly different ( P ≥ 0.05) from values obtained for fish fed the fish meal based (control) diet. Fish fed the enzyme treated feather meal in both trials 1 and 2 had higher values of growth performance and nutrient utilization than corresponding fish fed the hydrolyzed feather meal. However, composite mixture of hydrolyzed feather meal with soybean meal had considerable improvement on fish growth and nutrient utilization while there was no significant changes in the productivity values of fish fed enzyme feather meal with or without soybean meal dietary inclusion. Fish fed blood meal had the poorest productivity values but similar to fish fed hydrolyzed feather meal in weight gain and protein efficiency.

Characterization of Antibiotic-Resistant Bacteria in Rendered Animal Products

Antibiotics are used in food animal production to treat diseases and also to improve performance. Antibiotics are not used on all farms, and antibiotic resistance is occasionally found on farms that do not use antibiotics. Rendered animal protein products are often included in poultry feeds and could potentially serve as a source of antibiotic-resistant bacteria. One hundred sixty-five rendered animal protein products from cattle, poultry, and fish were aseptically collected from poultry feed mills. Fifty-five percent of the poultry meal samples had detectable levels of gram-negative bacteria ranging from 40 to 10,440 colony-forming units/g of sample. Poultry meal and meat and bone meal had the greatest number of samples with bacteria resistant to five or more antibiotics. A high percentage of feed samples (85%) contained bacteria resistant to amoxicillin, ampicillin, clavulanic acid, or cephalothin, whereas few samples contained bacteria resistant to ciprofloxacin, kanamycin, or trimethoprim/sulfamethoxazole. Acinetobacter calcoaceticus, Citrobacter freundii, and Enterobacter cloacae were the most commonly isolated antibiotic-resistant bacteria. Isolation for Salmonella was also performed, with 14% of the meat and bone meal samples containing Salmonella sp. Only one of the meat and bone meal isolates, Salmonella livingstone, was resistant to five or more antibiotics. Many of the antibiotic-resistant bacteria contained integrons, genetic elements that mediate multiple drug resistance.

Apparent digestibility of rendered animal protein ingredients for rainbow trout ( Oncorhynchus mykiss)

The apparent digestibility of 20 rendered animal protein ingredients from various origins was determined in three digestibility trials. The ingredients consisted of eight blood meals, four feather meals, six meat and bone meals and two poultry by-product meals. Within each type of ingredient, a relatively large range of raw materials, processing conditions and equipment were represented. In each of three trials, a reference diet was mixed with test ingredients in a 70:30 ratio to produce a series of test diets. The reference and test diets were fed to rainbow trout reared at 15°C and fecal samples were collected using the “Guelph system”. Apparent digestibility coefficients (ADC) for protein and energy of the four feather meals varied between 81 and 87% and 76 and 80%. Significant differences in the ADC for protein of feather meal were observed and may be related to the drying equipment. The ADC for protein of the two poultry by-product meals was 87 and 91% and that of energy 77 and 87%. The ADC for protein and energy of the six meat and bone meals varied between 83 and 89% and 68 and 83%, respectively. Treatment of one of the meat and bone meals by air-classification to reduce its ash content resulted in a significant increase in the ADC for protein and lipid. ADC for protein of the blood meals varied between 82 and 99% whereas ADC for energy varied between 79 and 99%. Spray-dried blood products (whole blood, blood cells, blood plasma) were highly digestible (ADC protein=96-99%). Rotoplate-, steam-tube- and ring-dried blood meals had significantly lower ADC for protein and energy than spray-dried blood products.