The influence of cecectomy on metabolizable energy and amino acid digestibility of select feedstuffs for white Pekin ducks

Estimation of the optimum digestible lysine level for Cherry Valley ducks

The aim of the current study was to determine the digestible lysine (DLys) requirement of Cherry Valley ducks from 1 to 14 d and from 15 to 35 d of age. One-day-old male Cherry Valley ducks (n = 320) were divided randomly and evenly into five treatments with 8 replicates of 8 birds. Ducks were fed adequate levels of digestible amino acid but with graded levels of DLys: 0.80, 0.88, 0.96, 1.04, and 1.12% from 1 to 14 d; 0.60, 0.68, 0.76, 0.84, and 0.92% from 15 to 35 d. At 35 d of age, 8 ducks per treatment were slaughtered for evaluating the yields of abdominal fat, subcutaneous fat, breast meat, and leg meat. Additionally, a 7-d metabolizable experiment was conducted with ducks of the same hatch beginning on d 35 (8 ducks per treatment). The results showed that the DLys level in diet had a quadratic relationship both with the average daily gain (ADG) and feed:gain ratio (F/G). According to the quadratic model, an optimum digestible lysine level was 0.948% from 0 to 14 d and 0.758% from 15 to 35 d based on ADG. The digestible lysine level for obtaining minimum F/G were 0.986% (0 ∼ 14 d) and 0.792% (15 ∼ 35 d), respectively. Breast meat yield (P = 0.110) and subcutaneous fat percentage (P = 0.021) showed a quadratic or linear response to the increasing dietary DLys level. To achieve maximum breast meat yield, the digestible lysine level of 0.961% and 0.761% were needed for the starter period (1 ∼ 14 d) and the growth period (14 ∼ 35 d), respectively. N excretion showed a quadratic response to the increasing dietary DLys level (P = 0.103). The results of the current study suggested that the optimum digestible lysine level was very different with the response criterion. The dietary digestible lysine levels were 0.948, 0.961% in the starter period (1 ∼ 14 d) and 0.758, 0.761% in the growth period (15 ∼ 35 d) for ADG, F/G, respectively.

Evaluation of amino Acid and energy utilization in feedstuff for Swine and poultry diets

An accurate feed formulation is essential for optimizing feed efficiency and minimizing feed cost for swine and poultry production. Because energy and amino acid (AA) account for the major cost of swine and poultry diets, a precise determination of the availability of energy and AA in feedstuffs is essential for accurate diet formulations. Therefore, the methodology for determining the availability of energy and AA should be carefully selected. The total collection and index methods are 2 major procedures for estimating the availability of energy and AA in feedstuffs for swine and poultry diets. The total collection method is based on the laborious production of quantitative records of feed intake and output, whereas the index method can avoid the laborious work, but greatly relies on accurate chemical analysis of index compound. The direct method, in which the test feedstuff in a diet is the sole source of the component of interest, is widely used to determine the digestibility of nutritional components in feedstuffs. In some cases, however, it may be necessary to formulate a basal diet and a test diet in which a portion of the basal diet is replaced by the feed ingredient to be tested because of poor palatability and low level of the interested component in the test ingredients. For the digestibility of AA, due to the confounding effect on AA composition of protein in feces by microorganisms in the hind gut, ileal digestibility rather than fecal digestibility has been preferred as the reliable method for estimating AA digestibility. Depending on the contribution of ileal endogenous AA losses in the ileal digestibility calculation, ileal digestibility estimates can be expressed as apparent, standardized, and true ileal digestibility, and are usually determined using the ileal cannulation method for pigs and the slaughter method for poultry. Among these digestibility estimates, the standardized ileal AA digestibility that corrects apparent ileal digestibility for basal endogenous AA losses, provides appropriate information for the formulation of swine and poultry diets. The total quantity of energy in feedstuffs can be partitioned into different components including gross energy (GE), digestible energy (DE), metabolizable energy (ME), and net energy based on the consideration of sequential energy losses during digestion and metabolism from GE in feeds. For swine, the total collection method is suggested for determining DE and ME in feedstuffs whereas for poultry the classical ME assay and the precision-fed method are applicable. Further investigation for the utilization of ME may be conducted by measuring either heat production or energy retention using indirect calorimetry or comparative slaughter method, respectively. This review provides information on the methodology used to determine accurate estimates of AA and energy availability for formulating swine and poultry diets.

Digestibility of amino acids in corn, corn coproducts, and bakery meal fed to growing pigs

The objectives of this experiment were to determine the apparent ileal digestibility and the standardized ileal digestibility (SID) of CP and AA in bakery meal, corn gluten meal, corn gluten feed, corn germ meal, and hominy feed and to compare these values with the apparent ileal digestibility and SID of CP and AA in corn and distillers dried grains with solubles (DDGS). Eight growing barrows (initial BW: 82.5 ± 5.5 kg) were randomly allotted to an 8 × 8 Latin square design with 8 diets and 8 periods. Diets contained corn, DDGS, bakery meal, corn gluten meal, corn gluten feed, corn germ meal, or hominy feed as the sole source of protein and AA. An N-free diet was used to measure basal endogenous losses of AA and protein. Pigs were fed experimental diets for eight 7-d periods, with ileal digesta being collected on d 6 and 7 of each period. Results indicated that the SID of Lys in corn gluten meal (78.7%) was greater (P < 0.01) than in DDGS, bakery meal, corn germ meal, and hominy feed (46.0, 48.4, 68.4, and 58.8%, respectively). The SID of all indispensable AA except Arg, Leu, and Met in bakery meal were not different from those in DDGS. The SID of Arg, His, Leu, and Met in corn gluten feed were less (P < 0.01) than in corn, but the SID of all other indispensable AA in corn gluten feed were not different from those in corn. However, for most indispensable AA, the SID in corn gluten feed was not different from the SID in DDGS. The SID of all indispensable AA in corn germ meal, except Arg, His, Leu, and Met, were not different from the SID in corn. Likewise, the SID of all indispensable AA in corn germ meal, except Arg and Leu, were not different from those in DDGS. The SID of Ile, Met, Phe, and Val in hominy feed were less (P < 0.01) than in corn, but the SID of the remaining indispensable AA in hominy feed were not different from the SID of indispensable AA in corn. All indispensable AA in hominy feed also had SID values that were not different from the SID values of AA in DDGS, except for Arg and Lys, which had greater (P < 0.01) SID than in DDGS. In conclusion, bakery meal had SID values of most AA that were less than in corn, but corn gluten meal had SID values for most AA that were greater than the SID of AA in corn, bakery meal, and corn coproducts.

Apparent ileal digestibility of amino acids in feedstuffs for White Pekin ducks

The apparent ileal amino acid digestibility of 6 feedstuffs, namely corn, wheat, corn distillers dried grains with solubles, canola meal, soybean meal (SBM), and meat and bone meal (MBM) were determined for White Pekin ducks in a 5-d experiment. The feedstuffs served as the sole source of amino acids in semipurified diets composed of dextrose, soy oil, Solka Floc, minerals, and vitamins, with the exception of corn and wheat, in which both lacked dextrose. The ducks received a standard duck starter diet during the first 14 d posthatch. On d 14, ducks were sorted by weight and allocated to 6 dietary treatments in a randomized complete block design. Each assay diet was fed to 8 replicates (6 ducks/replicate) from d 14 to 19 posthatch. Birds were killed on d 19 and digesta from the terminal ileum were collected. Ileal N digestibility was highest (P < 0.01) in SBM (88.3%) and lowest in MBM (72.4%). Ileal digestibility for all of the amino acids was highest in SBM among the feedstuffs. Lysine digestibility was highest (P < 0.01) for SBM followed by canola meal, corn, wheat, MBM, and distillers dried grains with soluble; the values were 90.3, 79.0, 78.0, 76.8, 75.6, and 69.2%, respectively. Methionine digestibility in SBM was highest (P < 0.01), whereas MBM had the lowest digestibility value for methionine (78.4%). For threonine, SBM (84.0%) had the highest digestibility and corn (61.6%) had the lowest digestibility (P < 0.01), but there were no differences among other feedstuffs. Ileal tryptophan digestibility was between 78.9 (MBM) and 93.0% (SBM). In conclusion, the data from the current study show that there are considerable differences among feedstuffs in the digestibility of their amino acids for ducks. Therefore, it is important to take the digestible amino acid content of feedstuffs into account during feed formulation.

The influence of caecectomy on amino acid availability of three feedstuffs for ganders

1. Experiments were conducted to assess the influence of caecectomy on amino acid availability (AAA) of three feedstuffs for goose. 2. Nine caecectomised and 9 intact Yangzhou ganders, 24 weeks old, were used in these experiments. Fish meal, soybean meal and cottonseed meal were used as the sole source of protein. The endogenous amino acid (AA) losses were evaluated by a nitrogen (N)-free diet method. The influence of caecectomy on apparent amino acid availability (AAAA) in fish meal, soybean meal and cottonseed meal was assessed in experiment 1 and true amino acid availability (TAAA) of three protein diets was determined in experiment 2. 3. Results showed that, in the soybean meal and cottonseed meal, the AAAA and TAAA of most AA determined by the intact ganders were higher than in the caecectomised ganders; in the fish meal, the AAAA and TAAA of most AA determined by the intact ganders were lower than in the caecectomised ganders. 4. Results of the present study suggest that the effect of caecectomy on AAA in geese was dependent on the feedstuff assayed, and it was better to use caecectomised poultry for AAA assessment.

Efficiency of methionine retention in ducks

The accretion of methionine and protein as a function of methionine intake was assessed in growing ducks between 22 and 42 d post-hatching. Four graded doses of dl-methionine at 0, 0·5, 1·0 or 1·5 g/kg diet were added to a methionine-limiting basal diet and fed to four replicate groups of four ducks each. The growth and efficiency of food use for growth increased linearly (P < 0·05) as a function of methionine intake. The accretion of body protein increased (P < 0·001) from 87·5 to 182·2 g, and that of methionine from 1616 to 3125 mg, over the 21 d period as dietary methionine increased. The accretion rate of methionine in the body (y, mg/d) as a function of methionine intake (x, mg/d) of ducks fed diets containing supplemental methionine at 0, 0·5, 1·0 or 1·5 g/kg diet from day 22 to day 42 post-hatching gave the regression equation: y = − 148·86 (se 32·558)+0·312 (se 0·0384)X, r2 = 0·8253. For protein accretion rate in the body (y, mg/d) as a function of methionine intake (x, mg/d), the regression equation was: y = − 9782 (se 2204)+19·505 (se 2·5994)x, r2 = 0·8009. There was a linear relationship between methionine (y, mg/d) and protein (x, mg/d) accretion in ducks that was described by the equation y = 12·757 (se 7·4019)+0·01 525 (se 0·00 107)x, r2 = 0·9355. The results of these studies suggest a constant utilisation of methionine over the range 2·4–3·9 g digestible methionine/kg diet, with an efficiency of 31 %. Furthermore, the results suggest a quantitative relationship of 15 mg methionine for every gram of protein accretion.

Metabolisable energy and amino acid digestibility of high-oil maize, low-phytate maize and low-phytate soybean meal for White Pekin ducks

1. Two experiments were conducted to determine the metabolisable energy and amino acid digestibilities of high-oil maize (HOM), low-phytate maize (LPM) and low-phytate soybean meal (LPSBM) as compared with normal maize (NM) and normal soybean meal (NSBM) using male White Pekin ducks. 2. In the first experiment, the TMEN (kJ/g) value of HOM (16.58) was higher than that of NM (16.05), but that of LPM (16.11) did not differ from those of HOM or NM. The true digestibility coefficients for methionine (0.874, 0.871 or 0.876), lysine (0.805, 0.816 or 0.813) and tryptophan (0.946, 0.959 or 0.960) did not differ among NM, LPM and HOM, respectively. The average true digestibility coefficients for all amino acids in NM, LPM or HOM (0.886, 0.890 or 0.900, respectively) did not differ among the three ingredients. 3. In the second experiment, the TMEN value of LPSBM (12.39) was approximately 8% higher than that of NSBM (11.46). The true digestibility coefficients for most amino acids were higher for LPSBM than for NSBM, except in the case of histidine, cysteine and tyrosine, which were not different. The average true digestibility coefficient for all amino acids in LPSBM (0.945) was higher than in NSBM (0.924). 4. Results of the two experiments indicate that the energy and amino acids in the feed ingredients evaluated were well utilised by ducks and that LPSBM has a higher energy value as well as digestible essential amino acid concentration than NSBM for ducks.

Additivity and associative effects of metabolizable energy and amino acid digestibility of corn, soybean meal, and wheat red dog for White Pekin ducks

The additivity of true amino acid digestibility (TAAD) and true metabolizable energy (TME) values in corn, soybean meal, and wheat red dog for White Pekin ducks was investigated. Differences between observed values for the complete diets and values predicted from measurements of individual ingredients were used to test additivity. Eight ducks were each assigned to the following dietary treatments: corn, soybean meal (44% CP), wheat red dog (wheat by-product with less than 4% fiber), complete Diet 1 (corn-soybean meal), complete Diet 2 (corn-red dog-soybean meal), and dextrose. Dextrose-fed ducks were used to estimate endogenous losses. The nitrogen-corrected TME (TMEn) in corn, soybean meal, wheat red dog, and two complete diets were 3.411, 2.919, 2.502, 3.148, and 3.111 kcal/g, respectively. In general, the TME and TMEn values observed in the two complete diets were not different (P > 0.05) from predicted values and indicated that the TME and TMEn in corn, soybean meal, and wheat red dog were all additive. The mean TAAD of corn, soybean meal, wheat red dog, and the two complete diets were not different, and were 87.03, 88.15, 90.58, 85.83, and 87.02%, respectively. The differences in TAAD between observed and predicted values were significant (P < 0.05) only for arginine, lysine, and aspartate in complete Diet 1, and for arginine, histidine, lysine, and aspartate in complete Diet 2. These results indicated that TME and TMEn values for corn,soybean meal, and wheat red dog were all additive in the two complete diets, but digestibilities of some amino acids were not additive and demonstrated some associative effects.

Additivity and associative effects of metabolizable energy and amino acid digestibility in barley and canola meal for White Pekin ducks

An experiment was conducted using the TMEn bioassay method to investigate the additivity and associative effects of metabolizable energy and amino acid digestibility in barley and canola meal for White Pekin ducks. Additivity was tested by comparing the difference between observed values determined in a complete diet and predicted values from measurements determined with individual ingredients (barley and canola meal). Six ducks each were assigned to diets of barley, canola meal, the complete diet, and dextrose. Dextrose-fed ducks were used for estimation of endogenous losses for calculation of true amino acid digestibility. The observed AME, TME, AMEn, and TMEn values in the complete diet were 0.065, 0.083, 0.016, and 0.023 (kcal/g), respectively, numerically higher than predicted values. Differences between observed and predicted values were not significant (P > 0.05), indicating that the AME, AMEn, TME, and TMEn in barley and canola meal were all additive. In general, observed values for apparent amino acid digestibility (AAAD) and true amino acid digestibility (TAAD) in the complete diet were higher than those predicted from individual ingredients. Observed AAAD for lysine, histidine, tryptophan, alanine, and aspartate were higher (P < 0.05) than predicted values, indicating that digestibilities of these amino acids were not additive. The mean of AAAD in canola meal (77.29%) was higher (P < 0.05) than the observed values of barley (52.2%) and complete diet (64.55%). For TAAD values, differences between observed and predicted values were significant for lysine, histidine, and tryptophan (P < 0.05). The mean of TAAD in canola meal, barley, and complete diet were 85.88, 80.87, and 81.33%, respectively. The average difference between observed and predicted values for TAAD (1.18 %) was smaller than that of AAAD (5.41%). These results indicated that ME values for barley and canola meal were additive in the complete diet but that digestibilities of some amino acids were not additive; they further suggested that there were some associative effects of amino acids in barley and canola meal for ducks.