Amino acid and phosphorus digestibility and concentration of digestible and metabolizable energy in hydrolyzed feather meal fed to growing pigs

Feeding pigs amino acids as protein-bound or in free form influences postprandial concentrations of amino acids, metabolites, and insulin

Dietary proteins need to be digested first while free amino acids (AAs) and small peptides are readily available for absorption and rapidly appear in the blood. The rapid postprandial appearance of dietary AA in the systemic circulation may result in inefficient AA utilisation for protein synthesis of peripheral tissues if other nutrients implicated in AA and protein metabolism are not available at the same time. The objective of this experiment was to compare the postprandial concentrations of plasma AA and other metabolites after the ingestion of a diet that provided AA either as proteins or as free AA and small peptides. Twenty-four male growing pigs (38.8 ± 2.67 kg) fitted with a jugular catheter were assigned to one of three diets that provided AA either in protein form (INT), free AA and small peptides (HYD), or as free AA (FAA). After an overnight fast and initial blood sampling, a small meal was given to each pig followed by serial blood collection for 360 min. Postprandial concentrations of plasma AA, glucose, insulin, and urea were then measured from the collected blood. Non-linear regression was used to summarise the postprandial plasma AA kinetics. Fasting concentrations of urea and some AA were higher (P < 0.05) while postprandial plasma insulin and glucose were lower (P < 0.01) for INT than for HYD and FAA. The area under the curve of plasma concentration after meal distribution was lower for INT for most AAs (P < 0.05), resulting in a flatter curve compared to HYD and FAA. This was the result of the slower appearance of dietary AA in the plasma when proteins are fed instead of free AA and small peptides. The flatter curve may also result from more AAs being metabolised by the intestine and liver when INT was fed. The metabolism of AA of the intestine and liver was higher for HYD than FAA. Providing AA as proteins or as free AA and small peptides affected the postprandial plasma kinetics of AA, urea, insulin, and glucose. Whether the flat kinetics when feeding proteins has a positive or negative effect on AA metabolism still needs to be explored.

Energy value of hydrolyzed feather meal and flash-dried poultry protein for broiler chickens and pigs

Three experiments were conducted to determine the metabolizable energy (ME) and nitrogen-corrected ME (MEn) contents of hydrolyzed feather meal (HFM) and flash-dried poultry protein (FDPP) for broiler chickens and to determine their digestible energy (DE) and ME for pigs. The energy-yielding ingredients in a reference diet (RD) were replaced at 0, 75, or 150 g/kg by HFM in experiment (Exp.) 1; at 0, 75, or 150 g/kg by FDPP in Exp. 2; and at 0, 150 g/kg HFM, or 150 g/kg FDPP in Exp. 3. Birds were fed a standard broiler starter diet from hatch to days 18 and 17 for respective Exp. 1 and 2, following which 144 birds (8 replicate cages of 6 birds per cage) were assigned to the three experimental diets in a randomized complete block design with body weight as the blocking factor. Experimental diets were fed for 5 d, and excreta were collected during the last 3 d. Twenty-four 20-kg barrows, individually housed in metabolic crates equipped with a feeder and drinker, were used in Exp. 3. The barrows were assigned to the three experimental diets in a randomized complete block design with body weight as a blocking factor. Following a 5-d adaptation period, feces and urine were collected for 5 d in a total collection method. Data were used to determine the regression-derived ME and MEn of HFM and FDPP for broiler chickens in Exp. 1 and 2, respectively. The DE and ME of HFM and FDPP for pigs in Exp. 3 were determined using the difference procedure. In Exp. 1, the inclusion of HFM linearly increased (P < 0.05) ME from 3,231 to 3,368 kcal/kg DM for 0 to 150 g/kg replacement of RD. The total tract retention of DM and metabolizability of energy linearly increased (P < 0.05) as replacement of RD with FDPP increased from 0 to 150 g/kg in Exp. 2. Inclusion of FDPP linearly increased (P < 0.01) ME from 3,425 to 3,591 kcal/kg DM. In Exp. 3, the diets containing 150 g/kg HFM or FDPP induced greater (P < 0.05) fecal DM and energy losses than the RD; however, the digestibility of energy across the three experimental diets was not different. The respective regression-derived ME and MEn of hydrolyzed feather meal for broiler chickens in the current study were 4,250 and 3,745 kcal/kg DM with corresponding values of 4,710 and 4,081 kcal/kg DM for flash-dried poultry protein. In pigs, 4,783 and 4,405 kcal/kg DM were the respective DE and ME of hydrolyzed feather meal, and 4,553 and 4,320 kcal/kg DM were the corresponding estimates for flash-dried poultry protein.

Comparative amino acid digestibility between broiler chickens and pigs fed different poultry by-products and meat and bone meal

The objective of this study was to compare the standardized ileal digestibility (SID) of amino acids (AA) in 3 poultry by-products including hydrolyzed feather meal (HFM), flash dried poultry protein (FDPP), and poultry meal (PM) and also a meat and bone meal (MBM) between broiler chickens and pigs. Experimental diets consisted of 4 diets containing each test ingredient as a sole source of nitrogen and a nitrogen-free diet. In experiment 1, 416 male broiler chickens with a mean initial body weight (BW) of 705 ± 100 g were allotted to 5 diets with 8 replicate cages per diet in a randomized complete block design with BW as a blocking factor at day 18 posthatching. After 5 d of feeding experimental diets, birds were euthanized by CO2 asphyxiation, and ileal digesta samples were collected from distal two-thirds of the ileum. In experiment 2, 10 barrows with a mean initial BW of 22.1 ± 1.59 kg were surgically fitted with T-cannulas at the distal ileum and allotted to a duplicate 5 × 4 incomplete Latin Square design with 5 diets and 4 periods. Each period lasted for 7 d including 5 d of adaptation and 2 d of ileal digesta collection. Data from experiments 1 and 2 were pooled together and analyzed as a 2 × 4 factorial arrangement with the effects of species (broiler chickens or pigs) and 4 experimental diets (HFM, FDPP, PM, or MBM). There were interactions (P < 0.05) between experimental diets and species in the SID of His, Lys, Thr, Trp, Val, and all dispensable AA except Tyr. In broiler chickens, the SID of Lys in FDPP (73.3%) was greater (P < 0.05) than in HFM (55.7%) but was lower (P < 0.05) than in MBM (86.5%), which was not different from PM (78.7%). In pigs, however, the SID of Lys in FDPP and PM (70.0 and 70.1%, respectively) were greater (P < 0.05) than in HFM (39.0%) but were lower (P < 0.05) than in MBM (79.2%). Broiler chickens fed FDPP and PM had lower (P < 0.05) SID of His, Thr, and Trp than those fed MBM; however, there was no difference in the SID of His, Thr, or Trp among pigs fed FDPP, PM, or MBM. The SID of Val in MBM was greater (P < 0.05) than in the other test ingredients for broiler chickens, but there was no difference in the SID of Val among test ingredients for pigs. Pigs had greater (P < 0.05) SID of Ile and Met than broiler chickens. In conclusion, the pattern of differences in the SID of His, Lys, Thr, Trp, and Val, but not the other indispensable AA, among poultry by-products and MBM were different between broiler chickens and pigs.

The direct and difference procedures result in similar estimates for amino acid digestibility in feed ingredients fed to growing pigs

An experiment was conducted to test the hypothesis that values for standardized ileal digestibility (SID) of amino acids (AA) in corn, wheat, and wheat middlings obtained using the direct procedure are not different from values obtained using the difference procedure. Sixteen ileal-cannulated barrows (initial BW: 69.5 ± 5.0 kg) were allotted to a replicated 8 × 4 Youden Square design with 8 diets and 4 periods. Each period consisted of 5 d of adaptation to the diet and 2 d of collection of ileal digesta. Four diets were based on soybean meal (SBM), corn, wheat, or wheat middlings as the only AA-containing ingredients. Three additional diets were based on a mixture of SBM and corn, SBM and wheat, or SBM and wheat middlings, and an N-free diet was also used. The apparent ileal digestibility (AID) and the SID of crude protein (CP) and AA for the 4 diets containing SBM, corn, wheat, or wheat middlings as the sole source of AA were calculated using the direct procedure. The AID and SID of CP and AA for the 3 mixed diets containing SBM and corn, wheat, or wheat middlings were also calculated and the contribution of digestible AA from SBM was subtracted from the AID or SID values for the diets. The AID or SID of AA in corn, wheat, and wheat middlings were subsequently calculated by difference. Results indicated that the AID values for a few AA were lower (P < 0.05) if the direct procedure was used instead of the difference procedure, regardless of ingredient. The AID of Trp was greater in corn and wheat middlings, and the SID of Trp in corn and wheat middlings tended to be greater, if the direct procedure rather than the difference procedure was used, but that was not the case for wheat (interaction, P < 0.05 and P < 0.10, respectively). However, for all other indispensable AA, and for most of the dispensable AA, the SID of AA in corn, wheat, and wheat middlings was not different between the difference procedure and the direct procedure. Therefore, values for SID of AA in cereal grains and fiber-rich ingredients may be determined using either the direct or the difference procedure.

Amino acid composition and digestible amino acid content in animal protein by-product meals fed to growing pigs1

An industry survey and animal experiment were conducted to evaluate the amino acid (AA) compositional variability and standardized ileal digestibility (SID) of AA in animal protein by-products fed to growing pigs. Animal protein by-product meals (212) were categorized into 8 groupings (blood meal, chicken by-product meal, chicken meal, feather meal, meat and bone meal, meat meal, poultry by-product meal, and poultry meal) and analyzed for total AA. Amino acid analysis among (e.g., Lys in blood meal averaged 9.20% compared with 2.31% for feather meal, DM basis) and within (e.g., Lys range of 1.54% in blood meal and 1.44% in feather meal, DM basis) the by-product classifications varied as expected, but on average the total AA values were similar to that reported in the literature. For the determination of the SID of AA, 15 barrows (average initial and final BW of 31.6 and 78.7 kg, respectively) were fitted with a T-cannula in the distal ileum and allotted to 15 diets over nine 7-d periods, resulting in 9 replications per diet. Pigs were fed a basal diet based on soybean meal and dehulled-degermed corn, 13 diets containing 17.5% animal protein by-product meal to partially replace a portion of the soybean meal and dehulled-degermed corn in the basal diet, or a N-free diet. Pigs were re-allotted to diets based on minimizing the number to times that the N-free diet would precede or follow feeding either of the blood or feather meal diets because of concern with inadequate diet consumption, as well as to prevent diets from being re-fed to the same pig during the next or subsequent periods. Values for the apparent ileal AA digestibility of each diet were determined, adjusted to SID based upon the endogenous AA losses determined by feeding the N-free diet, and the SID of AA in each animal protein by-product meal calculated using the difference procedure. The SID of AA varied among (e.g., SID of Lys averaged 91% in chicken meal but 47% in feather meal) and within (e.g., SID of Lys in three meat and bone meals was 80%, 71%, and 54%) the animal protein by-product meals, as would be expected and are consistent with variation reported in the literature. Overall, the data provide total AA composition for 212 samples and SID of AA for 13 samples of animal protein by-product meals, including data on their variability, which is critical for their use in feed formulation programs.

Amino acid digestibility in six sources of meat and bone meal, blood meal, and soybean meal fed to growing pigs

Standardized ileal digestibility (SID) of amino acids (AAs) by growing pigs was determined in blood meal and six sources of meat and bone meal (MBM). Eighteen ileal-cannulated barrows (initial body weight: 69.3 ± 4.4 kg) were randomly allotted to a replicated 4 × 9 incomplete Latin square design with four periods and nine diets, giving eight replications per diet. One diet included 33% soybean meal (SBM) as the sole source of AA. Seven diets contained 9% blood meal or 9% of one of the six sources of MBM and 22% SBM as the only AA containing ingredients. The last diet was a nitrogen (N) free diet. Results indicated that the SID of all AAs were different (P < 0.05) among the six sources of MBM, but the SID of lysine (Lys) could not be predicted from the ratio between Lys and crude protein. For some, but not all AAs, the average SID in MBM was greater (P < 0.05) than in blood meal, but for most AAs the SID in MBM was less (P < 0.05) than in SBM. It is concluded that, as is the case for most other co-products, differences in concentration and SID of AAs among sources of MBM exist.

Nutrient composition, digestible and metabolizable energy content, and prediction of energy for animal protein byproducts in finishing pig diets

An industry survey and animal experiment were conducted to evaluate compositional variability and DE and ME content of animal protein byproducts and to generate equations to predict DE and ME content based on chemical analysis. For the 220 samples collected, the greatest concentration of CP was observed in blood meal (BM) and the least in meat and bone meal (MBM) and the greatest concentration of ether extract was in meat meal and the least in BM, with ash content greatest in MBM and least in BM, with Ca and P levels being 36.1 and 16.3% of the ash content, respectively. For the balance experiment, a corn-soybean meal basal diet was used with test diets formulated by mixing 80% of the basal diet with 20% of the animal protein byproduct, except for BM, which was included at 10 and 20% of the test diets. Ten groups of 24 gilts (92.5 ± 7.4 kg final BW) were randomly assigned to the test or basal diet within each group, resulting in 16 replications per animal protein byproduct or basal diet, except for BM determinations (20 replications). Gilts were placed in metabolism crates and offered 2.4 kg daily of their assigned diet for 13 d, with total collection of feces and urine during the last 4 d. Gross energy in the diets, feces, and urine was used to calculate the DE and ME content of each ingredient by the difference procedure, using DE and ME of the basal diet as a covariate among groups of pigs. The DE content of the animal protein byproducts ranged from 5,367 to 2,567 kcal DE/kg DM, and ME ranged from 4,783 to 2,340 kcal ME/kg DM. Using all animal protein byproducts, the best-fit equations were as follows: DE (kcal/kg DM) = -2,468 + (1.26 × GE, kcal/kg DM), with of 0.84, SE = 390, and < 0.01, and ME (kcal/kg DM) = -2,331 + (1.15 × GE, kcal/kg DM), with of 0.86, SE = 327, and < 0.01. The apparent total tract digestibility (ATTD) of Ca and P were also determined using the difference procedure, with the average ATTD of Ca and P for the animal protein byproducts, excluding BM and feather meal, being 27.1 and 39.1%, respectively. These data indicate that DE and ME substantially varied among the animal protein byproducts and sources and that a variety of nutritional components can be used to accurately predict DE and ME for finishing pigs. In addition, it appears that high dietary inclusion rates of animal protein byproducts may result in low ATTD estimates of Ca and P, which may be due to excessive concentrations of total Ca and P affecting digestibility.