Dietary Apparent Metabolizable Energy and Amino Acid Density Effects on Growth and Carcass Traits of Heavy Broilers

Two experiments (EXP) were conducted to evaluate the interactive effects of dietary AME and amino acid (AA) density (total basis) on broiler chickens from 42 to 56 d of age. In EXP 1, diets were formulated to contain low AME (3,140 kcal/kg) and moderate AME (3,240 kcal/kg) in combination with moderate AA (16.2% CP, 0.88% Lys, and 0.75% TSAA) and high AA (18.0% CP, 0.98% Lys, and 0.83% TSAA) and fed to male broilers. Dietary treatments in EXP 2 were diets formulated to contain moderate AME (3,220 kcal/kg) and high AME (3,310 kcal/kg) combined with moderate and high AA concentrations used in EXP 1 and fed to male and female broilers. In general, dietary AME and AA did not interact to influence growth and meat yield responses. Broilers provided the low AME diet in EXP 1 consumed more feed and had poorer feed conversion but had higher total breast meat yield than birds fed the moderate AME diet. In EXP 2, broilers fed the high AME diet from 42 to 56 d had increased BW gain, decreased feed consumption, and improved feed conversion. Feeding the high AA diets in both EXP decreased feed consumption, improved feed conversion, and increased total breast meat yield. Nutritionists establishing nutritional programs for heavy broilers late in development from 2.5 to 3.6 kg may need to consider increasing AA density to optimize breast meat yield. Increasing the AME content of the diet improves feed conversion but not breast meat yield.     

Effects of exogenous enzymes in corn-based and Canadian pearl millet-based diets with reduced soybean meal on growth performance, intestinal nutrient digestibility, villus development, and selected microbial populations in broiler chickens

An experiment was conducted to compare a commercial corn-soybean meal diet with a pearl millet diet containing less soybean meal (-27%), alone or in combination with exogenous enzymes, on growth performance, jejunal villus development, ileal CP, and AA digestibility, and cecal microbial populations in broilers. One hundred sixty 1-d-old male Ross 508 broilers (5/cage) were randomly allocated to one of the following dietary treatments: 1) a standard corn-soybean meal control diet (CTL); 2) a pearl millet-soybean meal diet (PM); 3) CTL + exogenous enzymes (CE); and 4) PM + exogenous enzymes (PE) with 8 replicate cages/treatment. The PM and PE diets contained less soybean meal because of greater CP and AA contents of pearl millet. All diets were isonitrogenous and isocaloric. Body weight and feed intake were recorded weekly over 35 d. At d 21 and 35, 8 broilers per treatment were euthanized for sample collection and analyses. Gain-to-feed was greater (P < 0.01) for pearl millet- than corn-based diets. Apparent ileal digestibility (AID) of CP and most AA was similar between corn-based and pearl millet-based diets, and enzyme supplementation improved AID of CP (P < 0.01) and most AA at both d 21 and 35. However, for AID of some AA at d 21, the response to enzyme supplementation was less pronounced in broilers fed pearl millet-based diets than those fed corn-based diets (grain × enzyme, P ≤ 0.05). The villus was longer (P < 0.01) in broilers fed PM and PE than CTL and CE at d 35. Similarly, at d 35, lactobacilli loads were greater (P < 0.01) in broilers fed PM and PE than CTL and CE. It is concluded that, in comparison with corn, broiler diets formulated with pearl millet require less soybean meal and can be used to improve growth performance traits, intestinal lactobacilli populations, and villus development, whereas enzyme supplementation increases AID of CP and AA.     

Additivity of standardized ileal digestibility of amino acids in mixed diets containing multiple protein sources for growing pigs fed three crude protein levels

This study was conducted to investigate the effect of dietary crude protein (CP) levels of semi‐purified diets on the additivity of values for standardized ileal digestibility (SID) of amino acids (AA) in mixed diets from multiple protein sources for growing pigs. A total of 28 barrows (initial BW, 66.4 ± 1.3 kg) were surgically fitted with simple T‐cannulas at the distal ileum and assigned to a replicated 14 × 4 incomplete Latin square design with 14 diets and 4 periods. The 14 experimental diets consisted of a nitrogen‐free diet; a corn‐based diet (80 g CP/kg); nine semi‐purified diets containing soya bean meal (SBM), canola meal (CM) or corn distillers dried grains with solubles (cDDGS), each type (protein source) of semi‐purified diets supplied 80, 120 or 160 g CP/kg, respectively; three mixed diets based on corn, SBM, CM and cDDGS formulated to contain 120, 160 and 200 g CP/kg respectively. Pigs were fed each of the 14 diets during a seven‐day period, and ileal digesta were collected from 08:00 a.m to 6:00 p.m on day 6 and 7. Chromic oxide was added as an indigestible marker. Results indicated that the SID of CP and AA were not affected by CP levels (p > .05). Values for SID of AA were additive (p > .05) with the exception of His and Lys; Arg and Lys; Arg, Lys, Thr, Asp, Cys and Gly in the mixed diets containing 120, 160 and 200 g CP/kg respectively (p < .05). In conclusion, additivity of SID values of AA in the mixed diets at different CP levels was not affected by the CP levels of semi‐purified diets for growing pigs. Therefore, it is recommended that SID values of AA should be used to formulate practical diets containing multiple ingredients for pigs.     

Beneficial Effects of Versazyme,a Keratinase Feed Additive,on Body Weight,Feed Conversion,and Breast Yield of Broiler Chickens

Versazyme (VZ) is a keratinase-based feed additive. Broiler diets were formulated with low (95%), medium (100%), or high (105%) CP and amino acid levels relative to US Poultry Industry Reporting Service averages (2003). In each diet, amino acid minimums were maintained relative to the percentage of CP. The protein levels were as follows: starter—21, 22, 23%; grower—19, 20, 21%; finisher—17, 18, 19%; and withdrawal—16, 17, 18%. Mixed sex broilers 0 to 48 d of age were fed the 3 protein levels with and without VZ (0.10%) in a 3 × 2 factorial experiment. Statistical main effects indicated 48-d BW was greater on the high protein diets (2.42 kg) compared with low protein (2.36 kg), with the medium protein diet being intermediate (2.40 kg). Overall, VZ significantly (P < 0.01) improved 48-d BW 2.54% (from 2.36 to 2.42 kg, P < 0.01), feed conversion ratio 1.62% (from 1.912 to 1.881, P < 0.01), and breast meat yield 1.68% (from 31.57 to 32.10%, P < 0.01). The improvements in BW and feed conversion ratio by VZ were greatest with the low protein diets. However, VZ produced the greatest improvement in breast meat yield at the medium and high protein levels. This enzyme feed additive apparently improves the utilization of amino acids by broilers fed diets formulated to commercial specifications.     

Low crude protein diets supplemented with casein hydrolysate enhance the intestinal barrier function and decrease the pro-inflammatory cytokine expression in the small intestine of pigs

To reduce nitrogen excretion and lower feeding costs, low crude protein (CP) diets are sometimes proposed, however, a great reduction of dietary CP concentration (>4% reduction vs. recommended concentration), even supplemented with essential and nonessential amino acids (AA) can detrimentally affect small intestinal barrier function and immunity, possibly due to the excessive lack of peptides. Here we hypothesize that with an extremely low CP concentration diet, protein-derived peptides, rather than AA supplementation, can improve intestinal barrier development and health. To test this hypothesis, 21 growing pigs (19.90 ± 1.00 kg body weight) were randomly assigned to 3 treatments with control diet (16% CP), or low CP diets (13% CP) supplemented with AA (LCPA) or casein hydrolysate (LCPC) for 28 days. In comparison with the control diet, the LCPA diet decreased the protein expression level of jejunal barrier factor zonula occludens-1 (ZO-1) and stem cell proliferation factor leucine-rich repeat-containing G-protein-coupled receptor-5, whereas the LCPC diet enhanced intestinal barrier function by increasing the protein expression level of jejunal occludin and ZO-1 and ileal mucin-2. The LCPA diet reduced Lactobacillus counts, whereas the LCPC diet increased Lactobacillus counts and reduced Escherichia coli counts in the ileum. The LCPA diet also increased protein expression levels of pro-inflammatory cytokine interleukin-6 (IL-6) and IL-22, whereas the LCPC diet decreased protein expression levels of pro-inflammatory IL-1β, IL-17A and tumor necrosis factor-α in the ileum. Collectively, the casein hydrolysate supplementation of low CP diets showed beneficial effects on the small intestinal barrier, bacterial community, and immunity in pigs, pointing to the important role of protein-derived peptides in small intestinal health in cases of low crude protein diets.     

Effects of three major protein sources on performance,gut morphology and fermentation characteristics in broilers

ABSTRACT

1. This study determined the effects of three protein sources (PS), each at two digestibility crude protein (DCP) levels, on performance, gut morphology and fermentation characteristics in the hindgut of broilers.

2. It was hypothesised that broilers fed ingredients high in indigestible CP, i.e. rapeseed meal (RSM) or maize gluten (MG), could potentially cause reduced growth, impaired gut health, and more protein fermentation products in caecal digesta. Increasing the DCP level in each of the indigestible CP diets may compensate for these detrimental effects.

3. In total, 288 one-d-old male Ross 308 broilers were used in a completely randomised 3 × 2 factorial design, with six replicate pens per treatment. Three PS: soybean meal (SBM), rapeseed meal (RSM) or maize gluten (MG), and two DCP levels: 15.8 and 17.2% were used.

4. Broilers fed SBM had increased feed intake and BWG and improved FCR compared with those fed RSM and MG diets. Broilers fed high DCP had better performance compared with those on low DCP. No significant effects of PS or DCP level were found on gastrointestinal tract development, caecal ammonia or volatile fatty acid concentrations.

5. Broilers fed SBM had longer villi, smaller crypts and increased villus height to crypt depth ratio compared with those fed RSM and MG diets. Broilers fed RSM diet had a lower caecal pH, and had 16.5% and 14.9% more branched chain fatty acid contents in caecal digesta compared with those fed SBM and MG diets, respectively, indicating more proteolytic fermentation.

6. Replacing SBM by RSM and MG negatively affected growth performance and gut morphology. Hindgut protein fermentation was substantially increased in RSM fed birds.

7. To a certain extent, retarded growth performance in RSM and MG fed birds could be counterbalanced by increasing the dietary level of digestible CP.     

Use of Digestible Amino Acids and the Concept of Ideal Protein in Feed Formulation for Broilers

The objective of this study was to evaluate diet formulation based on digestible amino acids (DAA), the formulation of low protein diets supplemented with synthetic amino acids, and L-Thr supplementation to increase the Thr:Lys ratio from 67:100 to 70:100. Two experiments were carried out with Hubbard male broilers from 3 to 6 wk of age. In experiment 1, corn-soybean meal diets containing 20% CP were used. In experiment 2, 20% CP diets were formulated with corn, soybean meal, wheat bran, feather meal, and meat meal. In both experiments, body weight gain and economic evaluations were better for broilers fed diets formulated on DAA. Carcass yields and carcass composition were not significantly affected by formulation procedures. In experiment 2, birds fed diets based on DAA had improved feed efficiency compared with those fed total amino acids (TAA). In experiment 1, a reduction of CP from 20 to 18.2% did not affect broiler performance. It did, however, result in fatter carcasses, lower percentages of breast meat, and lower economic evaluation. In both experiments, performance and economic evaluation were not affected by the Thr:Lys ratio. In experiment 1, however, abdominal fat and carcass fatness were reduced, and, in both experiments, carcass protein level was higher with a Thr:Lys ratio of 70:100 than with 67:100 ratio (P < 0.05).     

Dietary protein levels and amino acid supplementation patterns alter the composition and functions of colonic microbiota in pigs

Different dietary nitrogen (N) patterns may have different effects on gut microbiota. To investigate the effects of different crude protein (CP) levels or essential amino acids (EAA) supplementation patterns on the structure and functions of colonic microbiota, 42 barrows (25 ± 0.39 kg) were randomly assigned to 7 dietary treatments including: diet 1, a high CP diet with balanced 10 EAA; diet 2, a medium CP diet with approximately 2% decreased CP level from diet 1 and balanced 10 EAA; diets 3, 4, 5, 6 and 7, low CP diets with 4% decreased CP level from diet 1. Specifically, diet 3 was only balanced for Lys, Met, Thr and Trp; diets 4, 5 and 6 were further supplemented with Ile, Val and Ile + Val on the basis of diet 3, respectively; and diet 7 was balanced for 10 EAA. Results over a 110-d trial showed that reducing the CP level by 2% or 4% dramatically decreased N intake and excretion (P < 0.05) in the presence of balanced 10 EAA, which was not observed when altering the EAA supplementation patterns in low CP diet (−4%). With balanced 10 EAA, 2% reduction in dietary CP significantly reduced Firmicutes-to-Bacteroidetes (F:B) ratio and significantly elevated the abundance of Prevotellaceae NK3B31 (P < 0.05); whereas 4% reduction evidently increased the abundances of Proteobacteria, Succinivibrio and Lachnospiraceae XPB1014 (P < 0.05). Among the 5 low CP diets (−4%), supplementation with Ile, or Val + Ile, or balanced 10 EAA increased F:B ratio and the abundance of Proteobacteria. In addition, the predicted functions revealed that different CP levels and EAA balanced patterns dramatically altered the mRNA expression profiles of N-metabolizing genes, the “N and energy metabolism” pathways or the metabolism of some small substances, such as amino acids (AA) and vitamins. Our findings suggested that reducing the dietary CP levels by 2% to 4% with balancing 10 EAA, or only further supplementation with Ile or Val + Ile to a low protein diet (−4%) reduced the N contents entering the hindgut to various degrees, altered the abundances of N-metabolizing bacteria, and improved the abilities of N utilization.     

Effects of feeding diets containing low crude protein and coarse wheat bran as alternatives to zinc oxide in nursery pig diets

Two experiments were conducted to determine the effects of crude protein (CP) level in diets containing coarse wheat bran (CWB) with or without pharmacological levels of Zn (provided by zinc oxide: ZnO) on growth performance and fecal DM of nursery pigs. In experiment 1, 360 barrows (Line 200 × 400, DNA, Columbus, NE, initially 5.6 kg) were allotted to 1 of 6 dietary treatments from d 0 to 21 after weaning with 5 pigs per pen and 12 pens per treatment. Treatments included a positive control diet (21% CP) with 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg in phase 2; negative control (21% CP) with 110 mg/kg added Zn, and 4 diets containing 4% CWB and 110 mg/kg added Zn formulated to contain 21%, 19.5%, 18%, or 16.5% CP. The 2 control diets and 21% CP CWB diet contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2, while the 19.5%, 18%, and 16.5% CP diets contained 1.33, 1.25 and 1.20% Lys, respectively, in both phases. Pigs fed the positive control diet containing pharmacological ZnO had increased (P < 0.05) ADG and G:F compared with the negative control and the 21% CP CWB diet. Reducing CP (concurrently with SID Lys) in diets containing CWB decreased ADG and G:F (linear, P = 0.002); however, fecal DM increased (linear, P = 0.005). In experiment 2, two groups of 300 and 350 pigs, initially 7.0 and 6.2 kg, respectively, were used with 5 pigs per pen and 26 pens per treatment. The objective was to determine if adding back essential AA would improve growth performance of pigs fed the low CP diets. All dietary treatments were fed for 13 days, contained 4% CWB, and consisted of: (1) positive control with 2,000 mg/kg of Zn and 21% CP (1.35% SID Lys); (2) no ZnO and 21% CP; and 3 diets with no ZnO formulated to 18% CP and (3) 1.2% SID Lys; (4) 1.35% SID Lys by the addition of feed grade amino acids (AA), and (5) diet 4 with non-essential amino acids (NEAA; Gly and Glu). Pigs fed 21% CP with ZnO had increased (P = 0.001) ADG compared to those fed 18% CP (1.35% SID Lys) with high levels of feed grade amino acids or those fed the reduced SID Lys (1.2%) diet. Overall, G:F was improved (P < 0.001) for pigs fed 21% CP diets and those fed the 18% CP diet with NEAA compared to pigs fed 1.2% SID Lys and pigs fed high levels of feed grade amino acids. Fecal DM was increased for pigs fed the reduced SID Lys diet. In summary, pharmacological levels of Zn improve pig growth performance, but reducing CP (and subsequently SID Lys) decreased nursery pig growth performance.     

Effect of dietary crude protein level on basal ileal endogenous losses and standardized ileal digestibilities of crude protein and amino acids in newly weaned pigs

The study was carried out to estimate basal ileal endogenous crude protein and amino acid losses (IAAL_B) and standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) originating from casein in newly weaned pigs from linear relationships between ileal recoveries and dietary intakes of graded levels of CP and AA. A total of 14 (12 + 2 for replacement) 3‐week‐old barrows weighing 5.7 kg was fitted with simple T cannulas at the distal ileum. At 28 days of age, the pigs were randomly allocated to the six experimental diets with two pigs per diet in four weekly repeated measurements. Corn starch‐based diets, containing six graded levels of CP from casein (90, 155, 220, 285, 350, 415 g/kg CP as‐fed basis respectively), were formulated. Titanium dioxide (TiO₂) was included as a digestibility marker. Each experimental period consisted of 7 days. Ileal digesta were collected for a total of 24 h during day 6 and 8. Splitting the total range of 90 to 415 g/kg CP into smaller ranges, i.e. from 90 to 220, 220 to 350 or 285 to 415 g/kg CP, provides estimates for CP and AA recoveries which are not significantly different from zero. As a result, dietary CP and AA originating from casein are completely digested and absorbed until the end of the small intestine. In addition, the use of large ranges of dietary CP levels showed that IAAL_B were affected (p < 0.050) by the dietary CP content. Accepting that ileal recoveries of CP and AA are exclusively of endogenous origin when purified corn starch casein‐based diets are fed, IAAL_B were estimated as a function of the dietary CP level. There were linear increases (p < 0.050) in IAAL_B when the dietary CP content was increased from 90 to 415 g/kg. Average IAAL_B expressed in g/kg dry matter intake (DMI) were 16.3, 0.7, 0.2, 0.9 and 0.2 for CP, lysine, methionine, threonine and tryptophan respectively. These values are in close agreement with IAAL_B obtained in grower‐finisher pigs.     

Effects of amino acids supplementation in low crude protein diets on growth performance,carcass traits and serum parameters in finishing gilts

This study investigated the effects of amino acids (AA) supplementation in low crude protein (CP) diets on growth performance and carcass characteristics in finishing gilts. One hundred and eighty gilts (59.1 ± 5.1 kg) were randomly allotted to one of five diets which consisted of a high CP (15.6%) diet or four low CP (11.6%) diets for 50 days. The low CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Gilts were housed at six pigs per pen with six pens per treatment. At the end of the 50‐day experiment, 30 gilts (one pig per pen) with average body weight (BW) of 98 kg were killed to evaluate carcass traits. The pigs fed the diet supplemented with LCV obtained the highest average daily gain (ADG), which was higher than those of pigs fed the diet supplemented with LCM (P < 0.05). Dietary supplementation with tryptophan, valine and isoleucine in low CP diets increased ADG (linear and quadratic effect, P < 0.05), serum levels of valine (quadratic effect, P < 0.05) and isoleucine (linear and quadratic effect, P < 0.05) and immunoglobulin G (IgG) and IgA (linear and quadratic effect, P < 0.05) in finishing gilts. © 2016 Japanese Society of Animal Science     

Influence of dietary protein level, amino acid supplementation, and dietary energy levels on growing-finishing pig performance and carcass composition

Two experiments were conducted to determine the effects of feeding reduced-CP, AA-supplemented diets at two ambient temperatures (Exp. 1) or three levels of dietary NE (Exp. 2) on pig performance and carcass composition. In Exp. 1, 240 mixed-sex pigs were used to test whether projected differences in heat increment associated with diet composition affect pig performance. There were 10 replications of each treatment with four pigs per pen. For the 28-d trial, average initial and final BW were 28.7 kg and 47.5 kg, respectively. Pigs were maintained in a thermoneutral (23 degrees C) or heat-stressed (33 degrees C) environment and fed a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (on an as-fed basis). Pigs gained at similar rates when fed the 16% CP diet or the 12% CP diet supplemented with Lys, Trp, and Thr (P > 0.10). Pigs fed the 12% CP, AA-supplemented diet had a gain:feed similar to pigs fed the 16% CP diet when housed in the 23 degrees C environment but had a lower gain:feed in the 33 degrees C environment (diet x temperature, P < 0.01). In Exp. 2, 702 gilts were allotted to six treatments with nine replicates per treatment. Average initial and final BW were 25.3 and 109.7 kg, respectively. Gilts were fed two levels of CP (high CP with minimal crystalline AA supplementation or low CP with supplementation of Lys, Trp, Thr, and Met) and three levels of NE (high, medium, or low) in a 2 x 3 factorial arrangement. A four-phase feeding program was used, with diets containing apparent digestible Lys levels of 0.96, 0.75, 0.60, and 0.48% switched at a pig BW of 41.0, 58.8, and 82.3 kg, respectively. Pigs fed the low-CP, AA-supplemented diets had rates of growth and feed intake similar to pigs fed the high-CP diets. Dietary NE interacted with CP level for gain:feed (P < 0.06). A decrease in dietary NE from the highest NE level decreased gain:feed in pigs fed the high-CP diet; however, gain:feed declined in pigs fed the low-CP, AA-supplemented diet only when dietary NE was decreased to the lowest level. There was a slight reduction in longissimus area in pigs fed the low-CP diets (P < 0.08), but other estimates of carcass muscle did not differ (P > 0.10). These data suggest that pigs fed low-CP, AA-supplemented diets have performance and carcass characteristics similar to pigs fed higher levels of CP and that alterations in dietary NE do not have a discernible effect on pig performance or carcass composition.     

Isoleucine and valine supplementation of a low-protein corn-wheat-soybean meal-based diet for piglets: growth performance and nitrogen balance

The effects of Ile and Val supplementation of a low-CP, corn-wheat-soybean meal-based piglet diet on growth performance, incidence of diarrhea, and N balance were studied using 60 Landrace x Duroc male piglets in a 4-wk experiment. The 60 individually caged piglets were divided into 5 dietary treatments, each consisting of 12 piglets. Diet 1 was a positive control diet (20% CP); diet 2 was a low-CP negative control diet (17% CP); diets 3, 4, and 5 were low-CP diets to which Ile, Val, or the combination of Ile and Val were added, respectively. All diets were supplemented with Lys, Met, Thr, and Trp to provide the required concentrations of these AA according to the 1998 NRC. Average daily gain and ADFI were similar among pigs fed the positive control, Val-added, and the Val plus Ile-added diets. On wk-2 and wk-4, fecal score was greater (softer feces) in piglets fed the 20% CP level compared with the remaining treatments (P < 0.01). Nitrogen intake was decreased (P < 0.0001) in pigs fed diets containing low levels of CP compared with pigs fed the 20% CP diet. Fecal N excretion (g/d) was decreased (P < 0.05) in piglets fed low-CP diets at wk 1 and wk 4 of feeding, and in urine at wk 4 of feeding. Crude protein levels or AA supplementation had no effect on N retention efficiencies. These results indicate that the supplementation of Val alone, or in combination with Ile, to a low-CP piglet diet with adequate levels of Lys, Met, Thr, and Trp is necessary to achieve maximum performance in pigs consuming corn-wheat-soybean meal-based diets.     

Studies on the Effect of Dietary Crude Protein Supply on the Composition of Ileal Endogenous Crude Protein Loss in Growing Pigs

Two experiments were carried out to investigate endogenous crude protein (N 2 6.25) (CP) losses in growing pigs. In experiment I, 42 cross-bred gilts [live weight (LW) 35-40 kg] were fitted with a simple T-cannula at the terminal ileum. Seven experimental diets (four feedstuffs: barley, wheat, soyabean meal and rapeseed meal, and three mixtures with varying compositions of the same feedstuff batches) were investigated. Each diet was fed at six different CP levels, obtained after dilution with a 1:1 mixture of sucrose and dextrose. In total, 42 different diets were used and on each pig three different diets were tested. In experiment II, 12 (LW , 18 kg) plus eight (LW , 88 kg) cross-bred castrates were fitted with a simple T-cannula at the terminal ileum. Four experimental diets based on casein as the sole protein source and with CP dietary levels from 6 to 25% were used. By extrapolation to zero CP intake the basal endogenous protein loss in experiment I was 15.7 g kg -1 dry matter (DM) intake, when including all diets, and 14.3 g kg -1 DM intake after excluding the barley diets. In experiment II the basal endogenous CP loss was 11.3 g kg -1 DM intake. In experiment I a relative increase in almost all amino acids in the endogenous CP loss was found when the dietary CP level in the diets increased from zero to 17%. Exceptions were glycine, which was constant, and proline, which decreased significantly from 176 to 58 g 160 g -1 CP. However, the sum of proline and glutamic acid in the endogenous protein loss was almost constant. Similar results were obtained after correction for undigested dietary CP and amino acids, based on in vitro analyses of CP digestibility. In a supplementary study, ileal samples, selected for unusually high levels of proline were analysed for free amino acids. For proline, 36-64% was free, whereas insignificant proportions of the other amino acids were free. It is concluded that the composition of endogenous CP is generally relatively constant. However, experimental conditions with low or inappropriate dietary CP supply may influence the composition and occasionally induce unexpected high levels of proline from secretion of free proline into the lumen of the digestive tract.     

Milk yield and composition of lactating Comisana ewes fed total mixed rations containing nitrogen sources with different ruminal degradability

The objective of this study was to examine the effects of pelleted total mixed rations (PTMR) containing two crude protein (CP) levels and N sources with different ruminal degradability on milk yield and composition of lactating ewes. The experiment, which lasted 14 weeks, was conducted during the spring and summer of 2007 and used 80 multiparous Comisana ewes in mid-lactation, reared in permanent stabling. A 2 × 2 factorial design was used, with ewes receiving two levels of CP (low 15.5% CP and high 17.5% CP) and two type of N sources with different rumen degradable protein (low and high) for each dietary treatment: (1) high-degradable protein diet (17.5% CP) composed by soybean meal, sunflower meal and urea (HPHD), (2) low-degradable protein diet (17.5% CP) included only corn gluten meal (HPLD), (3) high-degradable protein diet (15.5% CP) composed by soybean meal, sunflower meal and urea (LPHD), and (4) low-degradable protein diet (15.5% CP) included only corn gluten meal (LPLD). In order to evaluate in vivo digestibility of PTMRs, four adult rams were placed in metabolic cages and their individual faeces and urine were collected. In the performance trial, ewe milk yield was recorded daily and Individual milk samples were analysed weekly for milk composition and to determine milk renneting parameters. The 17.5% CP diets led to better nutrient apparent digestibility coefficients and had positive effects on milk production than the 15.5% CP diets. Similar results were obtained for corn gluten meal diets, compared to diets containing soybean meal, sunflower meal and urea. Data showed that corn gluten meal diets have had a positive effects on milk fat (P < 0.05), but not on milk protein, lactose and renneting parameters. All ewes gained weight during the experimental period, but the body weight change was not significant among treatments. Our findings indicate that an increase in rumen undegradable protein (RUP) content does not negatively affect nutrient digestibility of sheep rations and milk yield and composition.     

Production performance and plasma metabolite concentrations of broiler chickens fed low crude protein diets differing in Thr and Gly

The aim of the study was to test the interaction between Thr and Gly in low crude protein (CP) diets in 7 to 28 d broilers on production performance and plasma metabolites. A total of 2,040 broilers were allocated to 17 treatments. A positive control (PC) diet (20.5% CP) was formulated to be adequate in dietary Thr and Gly. A negative control (NC) diet (18.5% CP, deficient in Thr and Gly) was supplemented with crystalline l-Thr and Gly to obtain a 4 Thr × 4 Gly design. Dietary Thr was tested at an apparent faecal digestibility (AFD) Thr-to-Lys ratio, which was 55%, 58%, 61% or 64%, and dietary Gly was tested at an AFD (Gly + Ser)-to-Lys ratio, which was 135%, 142%, 149% or 156%. Plasma samples were collected at 28 d. The low CP diet, formulated at 64% Thr and 156% Gly, resulted in a higher body weight gain (BWG) (P < 0.01) and similar feed conversion ratio (FCR) as the high CP treatment (PC). FCR was improved (P < 0.001) by l-Thr supplementation. Quadratic response to dietary Thr was significant for feed intake (FI), BWG and FCR (P < 0.01). A near-significant interaction for Thr × Gly was observed for FI and BWG (P_linear = 0.091 and P = 0.074, respectively). Gly did not affect production performance. An interaction between Thr × Gly on plasma free AA level was observed (P < 0.05). Free AA concentration in plasma linearly decreased with increase in AFD Thr-to-Lys ratio, and increased with increase in AFD (Gly + Ser)-to-Lys ratio. Plasma uric acid concentration was higher in PC than in all of the other diets, and plasma triglyceride concentration was decreased by l-Thr supplementation, but not by Gly. In conclusion, Gly was not limiting for growth at low dietary CP level unless Thr was deficient, showing that adequate amounts of Thr in broiler diets can overcome marginal supply of Gly and Ser and allow reduction of dietary CP from 20.5% to 18.5% for broilers from 7 to 28 d of age.     

Effects of Excess Methionine from Meeting Needs for Total Sulfur Amino Acids on Utilization of Diets Low in Crude Protein by Broiler Chicks

Failure to obtain optimum performance by broilers fed low CP diets supplemented with amino acids may be due to a number of factors, including potential toxic effects of amino acids in excess of requirements. The objective of the present study was to evaluate the effect of excess levels of Met on performance of broilers fed low CP diets. Corn and soybean meal of known composition were used to formulate diets with 22, 20, 18, and 16% CP with 100 and 110% of NRC recommendations. DL-Methionine was used to meet Met and TSAA requirements; the dietary levels of Met exceeded minimum needs. Within each CP level, 2 additional series were prepared. For one series, only the amount of DL-methionine needed to reach the Met requirement was added, leaving a calculated deficit of TSAA. For a second series, excess Met was replaced with sufficient Cys to meet Met and TSAA exactly. Each of the test diets and a 23% CP positive control were fed to 6 replicate pens of 5 male broiler chicks from 1 to 21 d of age. Performance of the birds fed 22% CP diets did not differ significantly from that of chicks fed the positive control. Chicks fed diets with less than 22% CP had significantly lower BW and increased FCR regardless of level of amino acid supplementation. There was no significant effect of Met status on performance, indicating that corn-soybean meal diets do not appear to be deficit in Cys and do not respond to levels of Met greater than minimum NRC recommendations for Met. Excess levels of Met in this study did not appear to contribute to the reduced performance at low CP levels.     

Genotype and dietary lysine deficiency affect carcass and muscle amino acid composition of pigs growing from 10 to 25 kg body weight

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates—like fatty and lean pigs—may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty‐eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine‐adequate (AL) diet and lysine‐deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p < .01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p < .001–p < .05), and lower of methionine (p < .001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p < .001–p < .05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or nutritional challenges.     

Determination and prediction of the apparent and standardized ileal amino acid digestibility in cottonseed meals fed to growing pigs

This experiment was conducted to evaluate the chemical composition and apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) in cottonseed meals (CSM) and to develop prediction equations for estimating AA digestibility for growing pigs based on the chemical composition and AA content of CSM. 10 CSM were collected from 10 provinces in China. 11 barrows (initial body weight: 34.4 ± 1.9 kg), fitted with an ileal T‐cannula, were allotted to 6 × 11 Youden square with 6 periods and 11 diets. The diets included one N‐free diet and 10 CSM test diets containing 40% CSM as the sole source of AA. The nitrogen‐free diet was used to measure the basal endogenous losses of CP and AA. The AID and SID for crude protein (CP), Lys, Met, Trp, and Thr among the 10 CSM differed (p < 0.05). With R² values exceeding 0.30, significant linear regression equations for CP, Lys, and Thr were obtained. The best fit equations for predicting the AID and SID of Lys were: AID of Lys = 82.94–0.65 neutral detergent fiber, with R² = 0.44, residual standard deviation (RSD) = 4.03 and p = 0.04; and SID of Lys = 135.34–1.01 neutral detergent fiber + 34.27 Thr – 58.06 Trp – 84.93 Met, with R² = 0.90, RSD = 1.42 and p = 0.01. In conclusion, the results of AID, SID and prediction equations could be used to evaluate the digestibility of CSM in growing pigs.     

Raw mechanically separated chicken meat and salmon protein hydrolysate as protein sources in extruded dog food: effect on protein and amino acid digestibility

Protein quality was evaluated for mechanically separated chicken meat (MSC) and salmon protein hydrolysate (SPH), and for extruded dog foods where MSC or SPH partially replaced poultry meal (PM). Apparent total tract digestibility (ATTD) of crude protein (CP) and amino acids (AA) in the protein ingredients and extruded foods was determined with mink (Neovison vison). The extruded dog foods included a control diet with protein from PM and grain, and two diets where MSC or SPH provided 25% of the dietary CP. Nutrient composition of the protein ingredients varied, dry matter (DM) was 944.0, 358.0 and 597.4 g/kg, CP was 670.7, 421.2 and 868.9 g/kg DM, crude fat was 141.4, 547.8 and 18.5 g/kg DM and ash was 126.4, 32.1 and 107.0 g/kg DM for PM, MSC and SPH respectively. The content of essential AA (g/100 g CP) was more than 10.0 percentage units lower in SPH than in PM and MSC. The ATTD of CP differed (p < 0.001) between protein ingredients and was 80.9%, 88.2% and 91.3% for PM, MSC and SPH respectively. The ATTD of total AA was lowest (p < 0.001) for PM, and similar (p > 0.05) for MSC and SPH. In the extruded diets, the expected higher ATTD of CP and AA from replacement of PM with MSC or SPH was not observed. The ATTD of CP was determined to be 80.3%, 81.3% and 79.0% for the PM, MSC and SPH extruded foods respectively. Furthermore, the ATTD of several AA was numerically highest for the PM diet. Possibly, extrusion affected ATTD of the diets differently due to different properties and previous processing of the three protein ingredients.