Apparent metabolizable energy and ileal amino acid digestibility of commercial soybean meals of different origins in broilers.

We studied the chemical composition and the in vivo AMEn content and apparent (AID) and standardized (SID) ileal digestibility of CP and amino acids (AA) of 27 samples of soybean meals (SBM) from Argentina (ARG), Brazil (BRA), and USA, collected in Spain. On 88% DM basis, the BRA meals had more CP (46.9 vs. 46.0 and 45.9%; P < 0.05) and less sucrose (5.21 vs. 6.28 and 6.47%; P < 0.001) and stachyose (4.20 vs. 4.66 and 4.78%; P < 0.05) than the USA and ARG meals. Urease activity, protein dispersibility index, KOH protein solubility, and trypsin inhibitor activity values, were higher for the USA meals than for the South American meals (P < 0.05). In the in vivo trial, broilers received a common crumble diet from 0 to 16 d of age and then, their respective experimental diets (53% of a N-free diet and 47% of each of the 27 SBM tested) in mash form, for 5 d. The AMEn (2,334 vs. 2,282 and 2,277 kcal/kg; P = 0.062) and the AID (87.3 vs. 86.7 and 86.4%; P = 0.054) and SID (91.9 vs. 91.2 and 90.8%; P < 0.05) of the protein, were greater for the USA meals than for the ARG and BRA meals. In fact, the SID of Lys (93.5 vs. 93.0 and 92.1%; P < 0.001) and of the sum of Lys, Met, Thr, Trp, and Cys (91.4 vs. 91.0 and 90.2%; P < 0.05) were greater for the USA meals than for the ARG and BRA meals. In summary, the chemical composition, protein quality indicators, AMEn content, and ileal digestibility of the CP and the AA of the SBM, varied with the country of origin of the soybeans. In order to increase the accuracy of the feed formulation process, the composition and nutrient content of commercial batches of SBM, by country of origin should be controlled and periodically updated.

Influence of the calcium and nutrient content of the prelay diet on egg production, egg quality, and tibiae mineralization of brown egg-laying hens from 16 to 63 wk of age.

The influence of the Ca and nutrient content of the diet fed from 16 to 19 wk of age, on egg production, egg quality, and tibiae mineralization, was studied in brown egg-laying hens from 16 to 63 wk of age. The experimental design was completely randomized with 4 prelay diets organized as a 2 × 2 factorial with 2 levels of Ca (2.5 vs. 3.8%) and 2 standardized ileal digestible Lys (g/kg) to AMEn (Mcal/kg) ratios (DLys:ME; 2.84 vs. 3.13) as main effects. From 20 to 63 wk of age, all hens received a common diet with 2.75 Mcal AMEn/kg, 0.75% DLys, and 3.8% Ca. Each treatment was replicated 18 times and the experimental unit was a cage with 10 hens. Hen production and egg quality traits were measured by period (4 wk), feeding phase (prelay and lay), and cumulatively (16-63 wk of age) and tibiae mineralization was measured at 63 wk of age. During the prelay phase, an increase in Ca delayed egg production (P = 0.065), reduced feed intake (P < 0.05), and increased BW gain (P < 0.01) and percentage of shell of the egg (P < 0.05). An increase in the DLys:ME ratio increased feed intake (P < 0.01) and reduced egg size (P < 0.01). Nutrient content of the prelay diets did not affect hen production during the lay phase, except egg weight that increased (P < 0.05) in hens previously fed the low DLys:ME ratio. Eggshell quality (weight, percentage, strength, and thickness) in this phase was better (P < 0.05) in hens previously fed 3.8% Ca. Cumulatively (16-63 wk of age), hens fed the high Ca prelay diets had better shell quality but tibiae mineralization was not affected. In conclusion, an increase in Ca content of the prelay diet from 2.5 to 3.8% improved shell quality for the entire egg cycle without showing any negative effect on hen production.

Influence of the energy concentration and the standardized ileal digestible lysine content of the diet on performance and egg quality of brown-egg laying hens from 18 to 41 weeks of age.

The influence of the energy and the standardized ileal digestible lysine (DLys) content of the diet on egg production and egg quality, was studied in brown-egg laying hens from 18 to 41 wk of age. The experimental design was completely randomized with 10 treatments organized as a 2 × 5 factorial with 2 energy concentrations (2,750 and 2,800 kcal AMEn/kg) and 5 levels of DLys (values varied from 0.66 to 0.78% and 0.67 to 0.79%, for the low and high energy diets, respectively). Each treatment was replicated 10 times (10 hens per replicate). The data were analyzed using the MIXED procedure of SAS with energy concentration and DLys content of the diets as main effects. In addition, the effects of the DLys on the variables studied were partitioned into its lineal and quadratic components. From 18 to 21 wk of age (pre-peak phase), diet composition had limited effects on egg production. From 22 to 41 wk of age (peak phase), however, an increase of 50 kcal AMEn/kg diet increased egg weight (P < 0.05) and tended to improve energy intake (P = 0.083) and feed conversion ratio (P = 0.074). An increase in DLys improved linearly (P < 0.001) egg production, egg weight, egg mass, feed conversion, and energy conversion ratio, and tended to increase BW gain (P = 0.074). Diet composition did not any affect egg quality trait except shell strength that increased linearly (P < 0.05) with increases in the DLys. Cumulatively (18-41 wk of age), egg weight increased (P < 0.05) as the energy and the DLys content of the diet increased. In summary, an increase in energy and DLys content of the diet had limited effects on egg production during the prepeak phase but improved egg production, feed conversion ratio, and BW gain during the peak phase. The data indicate that hens require at least 839 mg DLys/d to maximize egg production in the peak production phase.

Influence of the energy and digestible lysine contents of the diet on performance and egg quality traits of brown-egg laying hens from 19 to 59 weeks of age.

The influence of nutrient density and standardized ileal digestible lys (DLys) content of the diet on egg production and egg quality traits, was studied in brown-egg laying hens from 19 to 59 wk of age. The experimental design was completely randomized with eight treatments arranged as a 2×4 factorial with two AMEn concentrations (2,680 and 2,780 kcal/kg) and four levels of DLys (0.68, 0.72, 0.76, and 0.80%). Each treatment was replicated nine times and the experimental unit was a cage with nine hens. Hen production, egg components (proportion of albumen, yolk, and shell), egg quality traits (Haugh units, egg shell strength, and incidence of broken, dirty, and shell-less eggs) were measured by period (28 d) and cumulatively. Data were analyzed as a completely randomized design with energy concentration, level of DLys, and their interactions as main effects. In addition, the effects of the level of DLys on the variables studied, were partitioned into its linear and quadratic components. No interactions between AMEn and DLys content of the diet were detected for any of the traits studied and therefore, only main effects are presented. An increase in the AMEn concentration of the diet from 2,680 to 2,780 kcal/kg increased energy intake (P < 0.05) and egg weight (P < 0.001) and improved feed conversion ratio (P < 0.05). An Increase in DLys from 0.68 to 0.80% did not affect the number of eggs produced but increased linearly egg weight (P < 0.01) and egg mass production (P < 0.05). Diet did not affect egg quality. In conclusion, an increase in the AMEn content of the diet from 2,680 to 2,780 kcal/kg increased egg weight and improved feed efficiency. Laying hens require no more than 744 mg DLys/d (corresponding to 0.68% DLys) to optimize egg production. However, when the objective is to maximize egg weight, hens should consume at least 843 mg DLys/d (corresponding to 0.76% D Lys).

The length of the feed restriction period affects eating behavior, growth performance, and the development of the proximal part of the gastrointestinal tract of young broilers.

We studied the effects of restricting the access to feed on the anticipatory eating behavior, growth performance, and the development of the proximal part of the gastrointestinal tract (GIT) in broilers. The experiment consisted in physical restriction of the access of broilers to feed for 0, 4, 6, or 8 h per day from 7 to 19 D of age. At 10, 13, 16, and 19 D of age, immediately before the start of the feed restriction (FR) period, 2 birds per cage were euthanized to evaluate crop and gizzard development. The experimental design was completely randomized, and the linear (L) and quadratic (Q) effects of fasting length on growth performance and GIT traits were determined. In addition, the effect of broiler age on GIT development was studied. From 7 to 19 D of age, ADFI (L, Q; P ≤ 0.05) and BW gain (L; P ≤ 0.01) decreased as the length of the FR period increased, with most of the differences observed with 6 or more hours of fasting. However, feed conversion ratio was not affected by FR length. The relative weight of the crop (% BW) and its fresh content increased (L; P ≤ 0.001) and the moisture of the digesta (%) decreased (L; P ≤ 0.001) as the FR period increased. The DM content (g) of the crop increased with FR, with most of the differences observed with 6 or more hours of fasting (L, Q; P ≤ 0.001). At 19 D of age, the Lactobacillus spp. count in the crop increased (L; P ≤ 0.05) with increase in the FR period. Fasting did not affect any gizzard trait at any age. In summary, physical restriction of the access to feed for 6 h or more reduced BW gain but did not affect feed conversion ratio in broilers from 7 to 19 D of age. Feed restriction for 4 to 8 h stimulated the anticipatory feeding behavior and crop development in broilers.

Influence of egg weight and inclusion of oat hulls in the diet on digestive tract traits and growth performance of brown pullets reared under stress conditions.

We studied the influence of pre-hatch egg weight (EW) and the inclusion of oat hulls (OH) in the diet on gastrointestinal tract (GIT) traits and growth performance of pullets reared under stress conditions early in life. There were 14 treatments organized as a 7 × 2 factorial with 7 EW groups (47.0 to 54.0 g differing in 1 g between groups) and 2 inclusion levels of OH in the diet (0 vs. 3%). The pullets were reared under a series of stresses early in life (no access to feed for extended time post-hatching, reduced accessibility to feed and water at arrival to the farm, reduced ambient temperature at night, low light intensity, and hot-blade beak trimming at 18 D of age). Feed intake, BW gain, and FCR were measured by period (0 to 5, 5 to 10, and 10 to 16 wk of age) and cumulatively. Data were analyzed as a completely randomized design with EW and OH inclusion as main effects. In addition, EW effect was partitioned into linear and quadratic components. The stress conditions applied affected similarly the growth and GIT development of the pullets, independent of EW. An increase in EW increased BW at hatch and at 5 wk of age linearly (P < 0.05), but no effects were detected thereafter. Oat hulls inclusion increased ADFI and impaired FCR (P < 0.05) from 0 to 5 wk of age but did not affect energy efficiency at any age. At 5 wk of age, the relative weight (% BW) of the GIT decreased linearly (P < 0.05) with increases in EW and increased with OH inclusion (P < 0.05). Oat hulls inclusion increased the relative weight of the gizzard at all ages (P < 0.01). In conclusion, egg weight did not affect pullet growth from hatch to 16 wk of age. Independent of the initial BW of the pullets, OH inclusion improved gizzard development at all ages without affecting growth performance.

Influence of beak trimming and inclusion of sodium butyrate in the diet on growth performance and digestive tract traits of brown-egg pullets differing in initial body weight.

We studied the effects of beak trimming and sodium-butyrate inclusion in the diet on growth performance and gastrointestinal tract (GIT) traits of brown-egg pullets differing in initial BW. In experiment 1, a total of 6 treatments were organized as a 2 × 3 factorial with 2 BW at hatch (light, 33.9 g and heavy, 37.6 g) and 3 beak trimming protocols [mild (MI-0) or aggressive (AG-0) infrared power setting at hatch and traditional hot blade at 8 D of age (HB-8)] as main effects. Initial BW did not affect growth performance or GIT traits at any age. From hatch to 5 wk of age, HB-8 pullets had lower ADFI (P < 0.01) and ADG (P < 0.05) than MI-0 and AG-0 pullets but no differences were detected after this age. Beak trimming did not affect FCR, BW uniformity, GIT traits, or bacteria count in the excreta at any age. In experiment 2, a total of 12 treatments were organized as a 2 × 3 × 2 factorial, with 2 BW at hatch, 3 beak trimming protocol (as per in experiment 1), and 2 levels of a sodium-butyrate additive (0 vs. 0.3%) as main effects. At 7 D of life, beak treatment reduced pullet growth and AG-0 procedure impaired pullet uniformity (P < 0.001) but the birds recovered completely by day 14 (P < 0.001 for the interaction with time). Cumulatively (0 to 6 wk of age), pullets beak treated at hatch (MI-0 and AG-0) had greater ADFI than HB-8 pullets (P < 0.01). Sodium butyrate tended to improve ADG (P = 0.073) and FCR (P = 0.069) with most of the benefits observed for the first 2 wk of life. In summary, initial BW and beak trimming procedure did not affect final pullet growth in any of the 2 experiments, or GIT traits in experiment 1. Sodium butyrate tended to improve growth and FCR from 0 to 6 wk of age but did not affect BW uniformity.