High Density Diet Research Articles

PSI-29 Enhancing growth performance and reducing environmental impact with dietary protease supplementation in growing pigs fed high- and low-density diets

Abstract Exogenous protease has emerged as a promising solution for enhancing protein digestion and utilization in animal diets, offering potential benefits for both animal performance and environmental impact mitigation in pig farming. In a 6-wk trial involving 140 growing pigs [initial body weight (BW) = 24.10 ± 1.66 kg], the effects of dietary protease supplementation on growth performance, nutrient digestibility, and noxious gas emission were investigated. Pigs were randomly assigned to one of four dietary treatments in a 2 x 2 factorial design with two levels of nutrient density and 0 or 125 g/ton supplementation of protease. The pigs were blocked by BW and housed in 28 pens with each pen consisting of 5 pigs (3 barrows and 2 gilts). The experimental design employed a randomized complete block design with 7 replicate pens per treatment. The data were analyzed using two-way ANOVA, with differences between means assessed using Tukey’s test (P < 0.05). Results revealed no significant interaction (P > 0.05) between nutrient density and protease supplementation concerning growth performance, nutrient digestibility, and noxious gas emission. Pigs subjected to high-density diets exhibited greater (P < 0.05) average daily gain (ADG) and gain-to-feed ratio (G:F) compared with those on low-density diets. While protease supplementation did not impact ADG and average daily feed intake (ADFI), there was a tendency towards reduced (P = 0.08) G:F throughout the 6-wk period. Pigs fed high-density diets demonstrated significantly greater (P < 0.05) apparent total tract digestibility (ATTD) of gross energy (GE) compared with their counterparts on low-density diets. Furthermore, the inclusion of protease significantly increased (P < 0.05) ATTD of GE. However, no discernible differences were noted among diets regarding the ATTD of dry matter and nitrogen. Regarding noxious gas emission, protease supplementation did not significantly affect total mercaptans and hydrogen sulfide (H2S) emission. Nonetheless, there was a notable trend towards reduced (P = 0.06) ammonia gas (NH3) emission with protease inclusion. Similarly, nutrient density did not exhibit a significant effect (P > 0.05) on noxious gas emission. In conclusion, the results of the study underscore the importance of nutrient density and protease supplementation in optimizing pig performance and environmental sustainability in swine production systems. Further research is warranted to elucidate the underlying mechanisms and refine strategies for maximizing the benefits of these dietary interventions.

The effect of diet density on allometry in pullet growth and early egg production

Understanding the effect of nutrition on pullet growth curves and body composition may help to design new feeding strategies that influence body composition and (long-term) laying performance. Therefore, this study examined the effect of nutrient density (low, medium or high metabolizable energy and essential amino acids), fed in the rearing phase until 17 wk of age, on Hy-Line white W80 pullet growth, body composition development and egg production performance until wk 35. Data were subjected to mixed model analyses. To determine a multiphasic allometric relationship between body components, an overall growth curve was established and inflection points were determined. The linear higher BW at the end of the rearing phase, due to increased diet density, was maintained during the peak production phase until wk 35. Egg production parameters were not affected by rearing diet density. Breast and body crude protein percentages were not influenced by dietary treatments, whereas body crude fat and abdominal fat pad percentages were linearly increased with diet density from early age onward. Body crude protein was initially deposited at the same rate as body dry matter. In a second phase of growth from wk 12 onward, crude protein deposition was lower than body dry matter deposition, but was not influenced by rearing diet. Body crude fat, on the other hand, initially grew at a lower rate than body dry matter, but increased in deposition rate during a second phase of growth starting at wk 2 to 5. Pullets fed the high density diet showed higher deposition of crude fat vs. dry matter as compared to pullets fed the medium density diets in the first phase until wk 2, but exhibited lower crude fat deposition in the second phase until wk 8. These results indicate that until approximately wk 12, crude protein deposition was mainly driving growth and was not influenced by diet density. From wk 5 to 6 onward, crude fat deposition relative to protein deposition increased and this was influenced by diet density from an early age.

Characterization of growth patterns and carcass characteristics of male and female broilers from four commercial strains fed high or low density diets

Over the last few decades, the poultry industry has seen the emergence of various market segments that are beneficial for rearing various flock sizes. Two concurrent experiments consisting of 1,200 broilers each were conducted to evaluate the effects of broiler size and diet on the performance of four commercially available broiler strains, including 2 standard yielding (SY) and 2 high yielding (HY) strains. Within each experiment (Experiment 1: males, Experiment 2: females), a small bird (38 and 40 d processing) and big bird (47 and 54 d processing) debone market were targeted to give variable carcass size. Two polyphasic diets were fed based on varying of amino acid densities. The low-density diet (L) consisted of 1.20, 1.10, 1.00, and 0.96% digestible Lys and the high-density diet (H) consisted of 1.32, 1.21, 1.10, and 1.06% across the 4-phases, respectively, with similar essential amino acid to digestible Lys ratios between the L and H diets in each phase. Weekly BW, BW gain, feed intake, and feed conversion ratio were assessed, as well as processing yields during both experiments. Broilers fed the H diets responded better than those fed the L diets, regardless of sex, with increased BW and decreased FCR (P < 0.05). Male HY strains provided the highest carcass yields (P < 0.05) compared to SY strains, with no differences observed in females (P > 0.05). High density diets (Diet H) also produced increases in carcass, breast, and tender yield (P < 0.05) for males, but that trend was not present in carcass yield for females (P < 0.05). Overall, strain impacted performance traits and carcass yields. Therefore, the use of specific strains and amino acid density for various market segments is beneficial for integrators to maximize return.

Partial corn replacement by glycerin and vegetable oils (cashew and castor) as alternative additive in the diets of crossbred bulls finished in a feedlot: Carcass characteristics and Longissimus lumborum muscle evaluation

This work was carried out to study the effects of corn grain replacement with glycerin (812 g of glycerol per kg/DM) and vegetable oils (cashew and castor) on the carcass characteristics and meat quality of Purunã bulls finished in a feedlot. A total of 32 Purunã bulls (¼ Aberdeen Angus + ¼ Caracu + ¼ Charolaise + ¼ Canchim) with a mean age of 12 ± 2.0 months and a mean body weight 206.1 ± 20.0 kg were distributed in a completely randomized design with four diets and eight replications per diet. The four experimental diets were as follows: CONT – basal diet; VOIL –basal diet and addition of vegetable oils (3 g/animal/day); GLYC – basal diet and addition of glycerin (20.1% glycerin on a DM basis); GLVO – basal diet and addition of glycerol (20.1% glycerin in DM basis) and vegetal oils (3 g/animal/day). The GLVO diet improved carcass conformation (+12.8%) in comparison with the CONT and GLYC diets. Likewise, fat thickness and proportion of fat in the carcass were higher in the GLVO group (+25.6% and +14.3%, respectively) versus the CONT group. Diets containing glycerin and vegetable oils increased hot (+5.0%) and cold (+5.1%) carcass weights, in comparison to the CONT diet. Diets containing vegetable oils (VOIL and GLVO) improved (+3.4%) carcass dressing relative to the CONT diet. Inclusion of glycerin and vegetable oils did not affect the Longissimus muscle area (68.0 cm2), texture (4.24 points), marbling (6.68 points), or colour (3.51 points) at 24 h post mortem. Likewise, instrumental colour in terms of lightness (32.4), redness (13.9), yellowness (4.94), chroma (14.8), and angle hue (19.1) at 24 h post mortem were unaffected by diet. Finally, the diet did not affect moisture (26.6%), ash (1.1%), crude protein (21.6%), total lipids (2.2%), WBS (3.1 kgf), TBARS (0.28 mg of MDA per kg of meat) or calories (225.5 kcal/100 g of meat). Thus, up to 20% glycerin on a DM basis and vegetable oils from cashew and castor could be added to the diet of bulls finished in a feedlot for 250 days and fed with a high-density energy diet.

Influence of Low and High-density Diets with Yeast Supplementation on Feed Intake, Nutrient Digestibility, Egg Production and Egg Quality in Hy-line Brown Laying Hens

A total of 432 laying hens (40 weeks old) were used in a 10- weeks feeding trial. The birds were randomly assigned to 1 of 4 treatments with 18 replications (6 birds per replication) in a 2×2 factorial arrangement with low-density diet (LD), and high density (HD) diets supplemented with or without (0.1 %) of yeast. Laying hens feed intake during the 5th, 6th and 10th weeks has significantly increased (p<0.05) in LD diet and HD diet supplemented with (0.1 %) of yeast supplementation. However, egg production and broken rate was not affected with or without yeast and density diet. The quality of egg and shell color during the 5th, 6th, and 7th weeks has significantly reduced (p<0.05) by yeast supplementation with HD and LD diet. Eggshell strength was significantly improved at week 4, moreover albumin height was also significantly improved by yeast supplementation diets at week 5. During week 1 and 2 the yolk color was higher in LD diet and HD diet compared with yeast supplementation. However, eggshell strength was significantly improved on HD diets than LD diets during the 4th and 7th weeks. Eggshell color and albumen height were significantly decreased in laying hens fed HD or LD diets during week 5 and 6. The apparent total tract digestibility (ATTD) of dry matter (DM), nitrogen (N), and Energy was not affected (p<0.05) by laying hens fed with or without yeast and HD than LD diets. In summary, 0.1% of yeast supplementation proved a positive impact on feed intake and egg quality of layer chicken.

Impact of varying starter amino acid density and energy on 42 d male Cobb MV × Cobb 500 broiler performance and processing

Summary Previous research has shown that feeding high amino acid density (AAD) diets or increased AME improved broiler performance, though the relationship between AAD and AME on performance needs to be further explored. Therefore, the objective of this study was to evaluate the impact of feeding 2 AAD and 4 AME levels from day 0 to 14 on performance and yield of 42-day-old Cobb MV × Cobb 500 males. Starter diets were formulated to medium or high AAD (HAA), and very low (VLE), low (LE), medium (ME), or high (HE) AME. Common diets were provided from day 15 to 41. A 2 × 4 factorial arrangement of treatments was used, with day 0 BW considered as a covariant. On day 0 to 14, birds receiving HAA had the lowest feed conversion ratio (FCR) corrected and uncorrected for mortality (uFCR). Birds receiving VLE diets had the highest day 0 to 14 FCR when compared to birds fed other AME levels. Feeding LE diets resulted in higher day 0 to 14 FCR when compared to ME and HE diets. An AAD × AME interaction for day 0 to 14 total Lys intake/bird found that Lys intake/bird decreased when increasing dietary AME for HAA diets. An AAD × AME interaction was observed for day 0 to 28 uFCR whereas increasing starter AAD in diets formulated to ME and HE increased day 0 to 28 uFCR; no change was observed for VLE and LE diets. However, overall performance and processing was not affected by varying starter AAD and AME levels. Further research should investigate similar feeding strategies, but in other feeding phases.

The Role of Incubation Conditions in the Onset of Avian Myopathies.

White striping, wooden breast, and spaghetti muscle have become common myopathies in broilers worldwide. Several research reports have indicated that the origin of these lesions is metabolic disorders. These failures in normal metabolism can start very early in life, and suboptimal incubation conditions may trigger some of the key alterations on muscle metabolism. Incubation conditions affect the development of muscle and can be associated with the onset of myopathies. A series of experiments conducted with broilers, turkeys, and ducks are discussed to overview primary information showing the main changes in breast muscle histomorphology, metabolism, and physiology caused by suboptimal incubation conditions. These modifications may be associated with current myopathies. Those effects of incubation on myopathy occurrence and severity have also been confirmed at slaughter age. The impact of egg storage, temperature profiles, oxygen concentrations, and time of hatch have been evaluated. The effects have been observed in diverse species, genetic lines, and both genders. Histological and muscle evaluations have detected that myopathies could be induced by extended hypoxia and high temperatures, and those effects depend on the genetic line. Thus, these modifications in muscle metabolic responses may make hatchlings more susceptible to develop myopathies during grow out due to thermal stress, high-density diets, and fast growth rates.

Effect of pullet body weight and hen dietary amino acid treatments on their progeny fed high and low amino acid diets

Four studies were conducted on Cobb 700 broilers to evaluate the dietary protein and any maternal effects on live production and processing parameters. Day-old Cobb 700 broiler breeder pullets were reared to conform to 2 different BW curves (control BW and increased BW) with 8 replicate pens per treatment. Birds were fed common diets from 1 d of age until first egg (24 wk). At 24 wk, 12 pens of each pullet treatment were given different amino acid (AA) diets (low = 14% CP, high = 15% CP). The performance of female and male progeny from 32 and 45 wk hens were evaluated on low AA and high AA density diets. The 4 progeny trial designs were identical factorial 2 × 2 × 2 designs, with 2 pullet BW curves (control BW and increased BW), 2 dam CP diet levels (low and high), and 2 progeny CP diets (low and high), with 6 replicates each containing 18 birds, for a total of 108 broiler progeny per treatment. Broiler chickens on the higher AA density feed exhibited consistent improvement in mid-growth BW and FCR and white meat yield percentage. Some maternal effects were noted, including increased carcass yield in female broilers from 32 wk old hens. There were 3-way interactions of pullet BW × hen dietary AA × progeny dietary AA treatments for female progeny carcass yield (from 32-week-old hens) and male tender yield (from 45-week-old hens). There were 2-way interactions of pullet BW x hen dietary AA treatments effect on female and male progeny drumstick yield from 32-week-old hens, pullet BW × progeny dietary AA treatments effect on male 27 d BW from 32-week-old hens, and hen dietary AA × progeny dietary AA treatments effect on male thigh yield from 45-week-old hen. The epigenetic effects of maternal pullet BW and dietary AA treatments were seen in processing yields suggesting, the need of dietary CP changes of the progeny.

High-density diet improves growth performance and beef yield but affects negatively on serum metabolism and visceral morphology of Holstein steers.

The objective of this study was to evaluate the effect of different dietary densities on growth performance, carcass characteristics, meat quality, serum metabolism, ruminal papillae morphology and liver injuries of steers. For this purpose, a total of eighteen Holstein steers were randomly fed one of the three diets: high energy and protein diet (H), standard energy and protein diet (C), and low energy and protein diet (L) for 11months fattening with three-step finishing strategy. Steers fed with H diet had higher (p<.05) average daily gain, feed efficiency, hot carcass weight, serum aspartate aminotransferase to alanine aminotransferase ratio, and monounsaturated fatty acids along with continuous low ruminal pH value, severer hepatic steatosis and ruminal papillae parakeratosis. Meanwhile, steers fed L diet increased the proportion of C20:0, C22:6n-3, saturated fatty acids and n-3 polyunsaturated fatty acids along with lower n-6 to n-3 ratio in longissimus dorsi muscle as compared to that of steers fed H diet. Dietary densities did not influence (p>.10) proximate nutrients and sensory characteristics of beef. The present study indicates that Holstein steers could achieve better growth and carcass performance under high-density diet, whereas they are under threat of visceral injuries and metabolic disorders. This study gives comprehensive relationship between productivity and animal health and suggests that a proper diet should be adopted for fattening Holstein steers in consideration of both beef quality and quantity and animal health.

Effects of Dietary Amino Acid Regimens on Live Performance and Processing Characteristics of Cobb MV × 700 Male and Female Broilers

The magnitude and timing of broiler responses to dietary amino acid (AA) density can vary between sexes and among genetic lines. Two experiments (Exp) were conducted to determine the responsiveness of Cobb MV × 700 broilers to changes in dietary AA density. In Exp 1, low (L), medium (M), and high (H) AA density diets were maintained across starter and grower phases in a 28 d growth performance trial (all males). In Exp 2, combinations of L, M, and H-AA density diets were varied across 4 feeding phases to evaluate the effect of 6 AA feeding regimens (HHHH, HHHM, HHMM, HMMM, MMMM, and HHLL) on growth performance, carcass composition, and breast muscle myopathies of broilers reared sex-separately. Body weight gain, feed intake (FI), and FCR responded positively to increased AA density during the starter and grower phases (0 to 28 d) of Exp 1. In Exp 2, broiler responses to AA density from 0 to 28 d diminished by the conclusion of the finisher phase (day 35), and FCR was the only measurement influenced by dietary AA density through day 46. Carcass characteristics and breast muscle myopathies were unaffected by AA density, with the exception of fat pad percentage, which decreased with increasing AA density. These data indicate that Cobb MV × 700 broilers may be less responsive to dietary AA density than other high-yielding broiler strains and further research to establish digestible AA:Lys ratios or dietary energy concentrations that optimize responses to increased AA density are warranted.

Effects of dietary amino acid density and feed allocation during the starter period on 41 days of age growth performance and processing characteristics of broiler chickens given coccidiosis vaccination at hatch

A study was conducted to determine if increasing digestible (dig) amino acid (AA) density or feed allocation of starter diets fed to broilers receiving coccidiosis vaccination can ameliorate poor cumulative growth performance and reduce meat yield. A total of 1,600 Yield Plus Ross × Ross 708 male broilers were assigned to a 2 × 3 factorial arrangement of dig AA density [moderate (1.15% dig Lys) and high (1.25% dig Lys)] and feed allotment (0.45, 0.73, and 1.00kg/bird) with 2 positive control treatments during the starter period. Diets were formulated to essential AA ratios relative to dig Lys. Vaccinated birds received a 1x dosage of Coccivac- B52 prior to placement, whereas non-vaccinated birds in the positive control groups were fed diets containing diclazuril. Following consumption of the starter diets, birds were provided common grower and finisher diets. Broilers fed the high AA density diet during the starter period had higher cumulative BW gain and lower cumulative feed conversion ratios (P < 0.05) than those fed the moderate AA density diet. Broilers fed the high AA density diet had heavier (P ≤ 0.005) carcass and total breast weights than birds fed the moderate AA density diet. Broilers fed a starter allotment of 1.00kg/bird produced heavier carcass weights (P ≤ 0.006) than did birds provided lower allotments. Additionally, broilers fed the high AA density diet had a greater percentage of 0 scores (P = 0.005) for the upper intestinal region during scoring. Results from this study indicated that feeding the high AA density diet at higher feed allotments during the starter period resulted in increased AA intake, which supported the bird through the vaccine challenge and enhanced the cumulative growth and meat yield.

Arterio-venous metabolomics exploration reveals major changes across liver and intestine in the obese Yucatan minipig

Blood circulation mainly aims at distributing the nutrients required for tissue metabolism and collecting safely the by-products of all tissues to be further metabolized or eliminated. The simultaneous study of arterial (A) and venous (V) specific metabolites therefore has appeared to be a more relevant approach to understand and study the metabolism of a given organ. We propose to implement this approach by applying a metabolomics (NMR) strategy on paired AV blood across the intestine and liver on high fat/high sugar (HFHS)-fed minipigs. Our objective was to unravel kinetically and sequentially the metabolic adaptations to early obesity/insulin resistance onset specifically on these two tissues. After two months of HFHS feeding our study of AV ratios of the metabolome highlighted three major features. First, the hepatic metabolism switched from carbohydrate to lipid utilization. Second, the energy demand of the intestine increased, resulting in an enhanced uptake of glutamine, glutamate, and the recruitment of novel energy substrates (choline and creatine). Third, the uptake of methionine and threonine was considered to be driven by an increased intestine turnover to cope with the new high-density diet. Finally, the unique combination of experimental data and modelling predictions suggested that HFHS feeding was associated with changes in tryptophan metabolism and fatty acid β-oxidation, which may play an important role in lipid hepatic accumulation and insulin sensitivity.

PSV-2 Effects of protease on growth performance, fecal gas emission of 25- to 55-kg pigs fed low or high density diets

Abstract Volatility in feed ingredient prices prompts animal nutritionists to evaluate alternative methods to control feed costs. The objective of this study was to evaluate the effects of protease in growing pigs fed either high or low-density diets. A total of 140 pigs [(Landrace×Yorkshire)×Duroc] were used in a 6-wk study with an initial BW of 24.1 ± 0.02 kg equally distributed in 7 pens per treatment fed one of the following treatments: High-density diet with 3400 kcal ME/kg, 19.5% CP, and 0.85% SID Lys; High-density diet + 125 g/t Jefo Protease (Jefo, Canada); Low-density diet with 3300 kcal ME/kg, 17.6% CP, and 0.83% SID Lys; and Low-density diet + 125 g/t Jefo Protease. Diets were corn, soybean meal-based with 12% rice bran and 8% wheat bran. Data were subjected to statistical analyses as a completely randomized design using a 2 × 2 factorial arrangement with pen as the experimental unit. Differences among treatment means were determined using Duncan’s multiple range test with level of significance at P ≤ 0.05. High-density diets (P = 0.01) and protease supplementation (P = 0.05) significantly improved G:F in pigs (Table 1) compared to low-density diets and no protease supplementation. NH3 and H2S gas emission tended to be lower (P ≤ 0.10) in diets supplemented with protease. There were no statistical differences (P &gt; 0.10) in initial weight, final weight, ADG, and ADFI. In conclusion, protease supplementation and high density diets improved G:F in 25- to 55-kg pigs.

Effect of dietary fermented corn in different energy dense diets on growth performance, nutrient digestibility, ileal microorganisms, and fecal noxious gas emission of growing pigs

This study evaluated the efficacy of fermented corn (FC) in growing pigs. One hundred twenty-eight growing pigs [(Landrace × Yorkshire) × Duroc)] with an initial body weight of 29.59 ± 1.34 kg were used in a 6 wk experiment. Pigs were assigned into one of four dietary treatments in a 2 × 2 factorial arrangement with two levels of nutrient density (high energy: 3.37 Mcal kg−1, or low energy: 3.29 Mcal kg−1) and FC (0% or 20% substitute for corn). Pigs fed diets with FC increased (P &lt; 0.05) average daily gain (ADG) overall. Pigs fed with high-density (HD) diets increased (P &lt; 0.05) ADG and gain to feed (G/F) ratio overall. Apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), and nitrogen (N) increased (P &lt; 0.05) in pigs fed with FC diets compared with pigs fed the diets without FC. In addition, pigs fed with HD diets increased (P &lt; 0.05) ATTD of DM and GE compared with low-density (LD) diets. Furthermore, pigs fed with HD diets had a higher (P &lt; 0.05) ATTD of DM and GE than those fed with LD diets. Both LD and FC supplementation led to lower (P &lt; 0.05) fecal gas emission content. Pigs fed FC diets increased ileal Lactobacillus concentration and decreased Escherichia coli concentration. An interactive effect between nutrient density diet and FC was observed on the G/F, Lactobacillus on ileal microorganisms, and nutrient digestibility. In conclusion, the results indicated that dietary supplementation of HD diets and FC improved performance in growing pigs.

96 Growth Performance, Nutrient Digestibility, Fecal Microbiota and Fecal Noxious Gas Emission in Weaning Pigs Fed High and Low Density Diet with and without Protected Organic Acid Blends.

96 Growth Performance, Nutrient Digestibility, Fecal Microbiota and Fecal Noxious Gas Emission in Weaning Pigs Fed High and Low Density Diet with and without Protected Organic Acid Blends.

86 Influence of Protease Supplementation to Corn-Soybean Meal Based High and Low Energy Diets on Growth Performance, Nutrient Digestibility, Blood Profiles, and Gas Emission in Growing Pigs.

A total of 140 growing pigs [Duroc × (Yorkshire × Landrace)] with an average body weight (BW) of 24.10 ± 1.66 kg were used in a 6-wk trial to determine the effect dietary protease supplementation in different energy diets in growing pigs. Pigs were randomly allotted to one of four dietary treatments in a 2 × 2 factorial design, with 2 levels of nutrient density (low or high nutrient density) and protease (0 or 125 g protease/ton) according to their sex and BW (7 pens with 3 barrows and 2 gilts/pen). Individual pig BW and pen feed consumption were recorded at the end of sixth week to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Fresh fecal samples were collected at the sixth week for calculation of dry matter (DM) and nitrogen (N) digestibility. All data were subjected to the mixed procedure of SAS for a randomized complete block design with a 2 × 2 factorial arrangement. Pigs fed the high density diets increased (P < 0.05) ADG, G:F, and energy digestibility compared with the low density diets during 6 weeks. The supplementation of protease in the diet did not have significant effect on BW, ADG, and digestibility of DM and N. However, at week 6, pigs fed the diet with protease supplementation increased energy digestibility (P < 0.05). In addition, trends in increased DM digestibility and G:F) (P = 0.08, P = 0.09 respectively) were observed. With regards to blood profiles, a significant increase in the level of creatinine at the 6th week and trends in increased blood urea nitrogen (BUN) (P = 0.06) and reduction in nor-epinephrine levels (P = 0.07) were also observed. Further more, ammonia gas emission, tended (P = 0.06) to reduce in the faeces of pigs fed protease supplemented diets. In conclusion, these results suggest that supplementation of growing pigs diet with protease significantly increased energy digestibility and creatinine levels, tended to increase G:F, DM digestibility, BUN, and decreased ammonia gas emission and norepinephrine levels. Key Words: digestibility; growth performance; pigs; protease. Table. Effect of different energy diet supplementations of protease on growth performance in growing pigs, wk 0 to 6 Table. Effect of different energy diet supplementations of protease on growth performance in growing pigs, wk 0 to 6

The interactive influence of dietary nutrient density and feed form on the performance of broiler chickens

The present study investigates the interactions between dietary nutrient density and feed form on the growth performance, coefficient of apparent ileal digestibility (CAID) of dry matter (DM), nitrogen (N), starch, fat, calcium (Ca) and phosphorus (P), and N-corrected apparent metabolisable energy (AMEn) in broiler chickens to 21d post-hatch. Maize-soybean meal diets with five tiers of nutrient density were formulated and mixed. The diets were then divided into two equal batches; the first batch was offered as unprocessed mash and the second batch was steam-pelleted at a conditioning temperature of 75 °C. A 5 × 2 factorial array of ten dietary treatments were offered to a total of 480, day-old male broiler (Ross 308) chicks accommodated in 60 cages (eight birds per cage). Significant (P < 0.001) interactions between nutrient density and feed form were observed for weight gain, feed intake and feed per unit gain. While birds fed pelleted diets outperformed those fed mash diets at each nutrient density level, the pellet-associated benefits were more pronounced at the lowest nutrient density. Increasing nutrient density increased (P < 0.001) N digestibility from 0.772 to 0.811, but decreased (P < 0.001) that of starch from 0.969 in very low density diets to 0.943 in very high density diets. No significant (P > 0.05) effect of nutrient density on the CAID of DM and fat was found. Feeding pelleted diets, regardless of nutrient density, reduced (P < 0.001) the CAID of DM, N, starch and fat. Significant nutrient density × feed form interactions were observed for the CAID of Ca (P < 0.001) and P (P < 0.01). Pelleting enhanced (P < 0.05) the CAID of Ca and P in the diet with lowest nutrient density but reduced (P < 0.05) the digestibility of these minerals in all other nutrient density diets. Increasing dietary nutrient density progressively increased the AMEn, but feeding of pelleted diets, regardless of nutrient density, reduced (P < 0.001) the AMEn. Overall, the present data showed that the magnitude of pelleting-induced benefits on broiler performance varied depending on dietary nutrient density, with responses to pelleting decreasing with increasing dietary nutrient density. The present study highlights that dietary nutrient density must be taken into consideration if the full benefits associated with feeding pelleted diets are to be achieved.

Growth performance, nutrient digestibility, fecal microbiota and fecal noxious gas emission in weaning pigs fed high and low density diet with and without protected organic acid blends

This study was conducted to evaluate the effects of dietary supplementation of protected organic acid blends including medium chain fatty acids and different nutrient density diets on growth performance, nutrient digestibility, fecal microbiota and fecal noxious gas emission in weaning pigs. A total of 90 crossbred [(Landrace × Yorkshire) × Duroc] weaning pigs with an initial body weight (BW) of 6.54 ± 0.78 kg were used in a six-week trial. Pigs were randomly allocated into one of six treatment groups in a 2 × 3 factorial arrangement with two nutrient density diets; high density (HD) vs low density (LD) supplemented with or without two levels (0.1 and 0.2%) of protected organic acids (OA) according to their sex and BW (3 replicate pens per treatment with 2 gilts and 3 barrows per pen). The inclusion of OA (0.1%, 0.2%) improved (P < 0.05) the average daily gain (ADG) during week 6. Likewise, during the overall experimental period, the ADG was higher (P < 0.05) in pigs fed HD diet than LD diet as well as in OA supplemented diet, but average daily feed intake (ADFI) was significantly improved (P < 0.05) only in diet supplemented with OA than non-supplemented diet. The gain: feed (G:F) ratio was higher (P < 0.05) in pigs fed HD than LD diet during week 3 and week 6 and overall experimental periods. The supplementation of OA (0.2%) led to a higher (P < 0.05) apparent total tract digestibility (ATTD) of energy during week 3 and week 6 compared with non-supplemented diet. In week 3, dry matter (DM) digestibility was higher in pigs fed diet supplemented with 0.2% OA but in week 6, DM digestibility was higher in both 0.1% and 0.2% OA treatments compared with control. The ATTD of energy was higher (P < 0.05) in pigs fed HD than LD diet during week 6. The supplementation of OA (0.2%) in the diet reduced fecal E.coli during week 3 and increased Lactobacillus counts during week 6. However, the fecal noxious gas emissions were not affected either by OA or diets. In conclusion, protected OA and different density diets improved growth performance, nutrient digestibility but no interactive effects with different density diets and OA were observed.

Effect of wheat-soy diet nutrient density and guanidine acetic acid supplementation on performance and energy metabolism in broiler chickens

The present study was carried out to investigate the effect of different levels of guanidine acetic acid (GAA) on the performance, carcase yield and energetic molecular metabolites of breast muscle in broiler chickens fed with wheat-soy diet containing different levels of nutrient densities. 450- day-old male broiler chicks (Ross 308), assigned in a completely randomised design experiment with factorial arrangement 3 × 3, 9 treatments and 5 replicates of 10 birds each. The diets included three levels of GAA supplementation (0, 0.6, 1.2 g/kg of diet) and three dietary nutrient density (ND) levels (low; 2800 kcal ME/kg, medium; 2950 kcal ME/kg and high; 3100 kcal ME/kg with constant rates of ME to other nutrients). The experimental diets were fed ad libitum from 1–42 days of age. One bird per pen was euthanized on day 10 and 42 to determine the energetic molecular metabolites concentrations of adenosine phosphate (ATP, ADP and AMP), phosphocreatine (PCr) and creatinine (CRN) in breast muscles. The inclusion of 0.6 g/kg GAA in wheat–soy diet, improved production performance, the relative weight of breast yield and increased the concentration of high phosphate energy metabolites (PCr, ATP/ADT and PCr/ATP) in breast muscle. The supplementation of high-density diet with GAA compared with the low-density diet improved broiler chicken’s performance. It is concluded that the use of GAA in diet may facilitate the conversion of high-energy phosphates to form ATP in muscles and thus improve broiler chicken’s performance.

Effects of light regimen and nutrient density on growth performance, carcass traits, meat quality, and health of slow-growing broiler chickens

The present study was conducted to examine the main and interactive effects of 4 light regimens [16h light (L):8h darkness (D), 23L:1D, decreasing-increasing (Dec-Inc), and intermittent lighting (3L:1D)], and 3 dietary nutrient densities (low-, medium-, and high-density) on the growth performance, carcass characteristics, meat quality, and health of slow-growing broiler chickens (Beijing-You). A total of 14401-d-old broiler chickens were assigned to light regimens and nutrient densities in a 4×3 factorial arrangement of treatments with 4 pens per treatment and 15 males and 15 females per pen. Body weight and accumulated feed intake were determined on d 28, 56, and 91. The gait score (GS) was recorded to assess leg health on d 91. Two males and 2 females from each pen were randomly selected and processed to determine the weight of eviscerated carcass, breast muscle, thigh muscle, and abdominal fat. Meat quality was determined using the breast fillet. The ovary, testis, and comb were weighed, and the serum follicle stimulating hormone (FSH) and testosterone concerntration were determined for females and males, respectively. There was no interaction for any of the response criteria except for feed conversion ratio (FCR) from d 0 to 28 (P=0.014). The ADFI from d 56 to 91 of broiler chickens under 16L:8D regimen were greater than other 3 regimens (P<0.05), and they had larger testis and comb percentage and greater testosterone concentration than those under 23L:1D regimen (P<0.05). The broiler chickens under Dec-Inc regimen deposited less abdominal fat than those under 3L:1D and 23L:1D regimens (P<0.05), and they had larger testis and comb percentage and greater testosterone concentration than those under 23L:1D regimen (P<0.05). The ADFI and FCR from d 0 to 91 were affected by diet nutrient density, with medium- and high-density resulted in lower ADFI and FCR (P<0.05). The females fed the medium- and high-density diets also had greater ovary percentage and FSH concerntration (P<0.05). These results indicated that medium-density diet is the most appropriate for slow-growing broiler chickens. The 23L:1D regimen did not show any superiority on the improvement of feed conversion or meat quality. The Dec-Inc regimen improved feed conversion and carcass traits and enhanced the development of sex characteristics. Therefore, the medium-density diet and Dec-Inc regimen are suggested for the slow-growing broiler chickens.