Effects of chromium propionate on growth, carcass traits, and pork quality of growing-finishing pigs1,2

Influence of Dietary Supplementation of Inorganic and Organic Chromium on Body Conformation, Carcass Traits, and Nutrient Composition in Muscle and Internal Organs of Black Bengal Goats

The effect of dietary inorganic and organic chromium (Cr) on body morphometry, carcass traits, and nutrient composition, including different minerals and fatty acids in meat and internal organs of Black Bengal goats, was studied. Thirty weaned Black Bengal kids of 3-5 months (5.40 ± 0.34 kg body weight) were assigned randomly into five groups and fed additional Cr for 150 days. The experimental diets comprised a basal diet supplemented with Cr at the rate of 0 (control; without Cr supplementation), 1.0 and 1.5 mg/kg of inorganic Cr (Cr(III)-chloride), and 1.0 and 1.5 mg/kg of organic Cr (Cr-yeast). The body morphometry such as body length, heart girth, paunch girth, loin width, leg circumference, and the carcass traits, namely, slaughter body weight, dressing percentage, hind quarter and forequarter weight, and rib eye area of goats, were not significantly (P < 0.05) changed due to inorganic and organic Cr supplementation. However, organic Cr supplementation (1.0 and 1.5 mg/kg) resulted in a reduction of breast and back fat thickness (P < 0.05) compared with the control group. The weights of internal organs including liver, lungs, spleen, kidney, testes, and heart and their weights as a percentage of slaughter weight were similar (P > 0.05) among different experimental groups. Dry matter, ether extract, and total ash concentrations of muscle and internal organs of Cr-supplemented groups were not affected (P > 0.05) by Cr supplementation. However, crude protein contents in the liver, muscle, kidney, and lungs were greater (P < 0.05) in the organic Cr groups than in the control and inorganic Cr groups. In meat (longissimus dorsi muscle), total saturated fatty acid concentration was lower (P < 0.05; 59.4% versus 55.7%) and the unsaturated fatty acid concentration was greater (P < 0.05; 40.6% versus 44.3%) including palmitoleic acid, heptadecenoic acid, elaidic acid, and arachidonic acid in the organic or inorganic Cr-supplemented groups than in the basal diet group. In conclusion, dietary supplementation of organic Cr in Black Bengal goats has no influence on the carcass traits, but may improve the meat quality with greater protein content, lean, and healthier fatty acids for human consumption.

Nutritive evaluation of dried cabbage (Brassica oleracea var. capitata) waste meal as feed for grower-finisher pigs

This research investigated the nutritive value of dried cabbage waste meal (CWM) as feed for grower-finisher pigs. One hundred crossbred (Large white X Landrace; 86.10 ± 0.15 kg BW) clinically certified grower-finisher pigs of equal sexes were randomly allocated to five dietary treatments with five replicates per treatment in a completely randomized design. The control diet (T0 Diet) contained 1000 g kg-1DM concentrate without CWM, while diets T50, T100, T150 and T200 had 50, 100, 150 and 200 g kg-1 DM levels of inclusion of CWM, respectively, replacing parts of the total mixed ration (TMR). Data were collected on growth performance, carcass indices, blood biochemical profiles, and economics characteristics of pigs. The study lasted for 8 weeks. Feed and water were available ad libitum. Feed intake (2336.74-2651.01 g/d) increased (p < 0.05) while weight gain (913.04-877.53 g/d) and feed conversion ratio (2.56-3.02) were better (p < 0.05) among pigs fed T0, T50 and T100 diets. Carcass parameters followed the same trend as growth indices (p < 0.05). Red blood cell counts (6.04-8.57 × 1012/L), haemoglobin (15.10-18.35 g/dl) and neutrophils (21.28-25.88%) concentrations increased (p < 0.05) among pigs fed cabbage waste meal. Aspartate aminotransferase concentrations (33.25-40.23 U/L) increased (p < 0.05) significantly among pigs fed T100, T150 and T200 diets. Total cost of feeding (61.19-56.27 $) reduced (p < 0.05) with similar gross benefits (48.97-52.30 $) across the treatment groups. The results suggest that up to 100 g kg-1 CWM could be incorporated into pig diets to improve their growth performance and support profitable pig production.

Meta-Analysis of the Effects of Organic Chromium Supplementation on the Growth Performance and Carcass Quality of Weaned and Growing-Finishing Pigs

Many factors influence the effects of exogenous organic chromium (EO-Cr) on the growth performance and carcass qualities of weaned and growing-finishing pigs, such as pig growth stages, types of EO-Cr, period of supplementation, and farm management. However, it is challenging to comprehensively consider all factors in one study. To solve this problem, we searched all relative literature published from 1 January 2000 to 1 January 2023, to systematically analyze and review the effects of EO-Cr on pig growth performance and carcass qualities via meta-analysis. Thirty-five papers were filtered and analyzed, which involved 4366 pigs. The results showed that, for weaned piglets, EO-Cr diets significantly increased the average daily gain (ADG, p < 0.001) and average daily feed intake (ADFI, p = 0.022) but reduced the feed-gain ratio (p = 0.004). In addition, for growing-finishing pigs, EO-Cr supplementation significantly increased the ADG (p < 0.001), carcass lean ratio (p = 0.020), and loin muscle area (p < 0.001), but had no significant effect on the ADFI (p = 0.071), feed-gain ratio (p = 0.692), dressing percent (p = 0.989), or back fat thickness (p = 0.142). Moreover, the effect of EO-Cr was greater in weaned piglets than in growing-finishing pigs. In terms of the dose effect of the supplement, chromium nicotinate is the most suitable EO-Cr type for weaned piglets with an optimal dosage range of 0.125-0.150 mg/kg. On the other hand, chromium picolinate is the most suitable EO-Cr type for growing-finishing pigs with an optimal dosage range of 0.250-0.300 mg/kg. In conclusion, EO-Cr supplementation is beneficial for enhancing the growth performance and carcass qualities of both weaned and growing-finishing pigs.

Effects of dietary chromium propionate on laying performance, egg quality, serum biochemical parameters and antioxidant status of laying ducks under heat stress

Recent studies have shown that chromium (Cr) could alleviate the negative effects of heat stress on livestock and poultry, but there is little information available to laying ducks. This study aimed to investigate the effects of dietary addition of chromium propionate on laying performance, egg quality, serum biochemical parameters and antioxidant status of laying ducks under hot (average 32 °C) and humid (average 75% relative humidity) summer conditions. A total of 900 66-week-old weight- and laying-matched Shanma laying ducks were randomly divided into five treatments, each with 6 replicates of 30 individually caged birds. The birds were fed either a basal diet or the basal diet supplemented with either 200, 400, 600, or 800 μg/kg Cr as chromium propionate. All laying ducks were given feed and water ad libitum for 5 weeks. The results showed that dietary supplementation with chromium propionate significantly increased the laying rate and yolk colour score (P < 0.05). Treatment with 400 μg/kg Cr as chromium propionate significantly decreased the feed/egg ratio by 5.4% (P < 0.05). Increased supplemental Cr from 0 to 800 μg/kg resulted in an increase in albumen height and the Haugh unit linearly (P < 0.05). Increased supplemental Cr decreased serum cortisol (P < 0.001, linear; P = 0.008, quadratic), heat shock protein-70 (P < 0.001, linear; P = 0.007, quadratic) and glucose (P = 0.007, linear), whereas it increased serum insulin (P = 0.011, Linear), total protein (P = 0.006, linear; P = 0.048, quadratic) and albumin (P = 0.035, linear; P = 0.088, quadratic). Dietary Cr levels increased the activities of superoxide dismutase and glutathione peroxidase, the total antioxidant capacity linearly and quadratically (P < 0.05). A linear and quadratic (P < 0.05) decrease of the malondialdehyde concentrations in response to dietary Cr level was observed. These results indicated that dietary supplementation of Cr as chromium propionate, particularly at 800 μg/kg could beneficially affect the laying rate, egg quality and antioxidant function, as well as modulate the blood biochemical parameters of laying ducks under heat stress conditions.

Chromium propionate improves performance and carcass traits in broilers

There is evidence to suggest that poultry may have a dietary requirement for metabolically available chromium (Cr) that exceeds the amount provided through wheat soybean meal diets. The objective of the present study was to investigate the effects of dietary supplemental organic Cr from Cr propionate at different dose levels (control = 0 μg/kg, T1 = 200 μg/kg, T2 = 400 μg/kg) on the growth performance, carcass traits, and meat quality of broilers. Weight gain and feed intake of each treatment were recorded at the start and after 14, 28 and 35 d, and feed conversion ratios (FCR) were calculated accordingly. At 35 d of age, birds were randomly selected and euthanized for carcass evaluation. Results of the first trial indicate that both Cr propionate treatments increased final body weight (P < 0.05), feed efficiency (P < 0.05) and body weight gain (P < 0.0001). Furthermore, Cr propionate supplementation improved (P < 0.0001) all carcass characteristics. Interestingly, with increased Cr dosage, carcass yield, dressing percentage and breast meat yield increased linearly (P < 0.0001). The second study reveals that the feed intake in the control group was significantly higher compared to both Cr propionate supplemented groups (T1 & T2). Furthermore, the Cr propionate supplemented T2 group displayed a significantly lower FCR than the control and T1 group (P = 0.027). Finally, Cr propionate supplementation increased the dressing percentage compared to control birds (P < 0.0001). In the third experiment, Cr propionate supplementation (T1 & T2) increased final body weight and decreased FCR compared with the control treatment. These effects were highly significant (P < 0.0001) throughout all feeding phases of the trial. Cr propionate supplementation also increased (P < 0.0001) carcass yield, dressing percentage, breast meat yield, leg and thigh weights compared with the control treatment. In conclusion, growth performance, feed conversion, carcass yield, breast and leg meats of broiler birds can be significantly improved by dietary inclusion of Cr propionate. Cr propionate can be supplemented to broiler birds from 1 d old of age at a level that provides 200 or 400 μg/kg organic Cr and can increase the efficiency of broiler production.

Influence of chromium propionate dose and feeding regimen on growth performance and carcass composition of pigs housed in a commercial environment. Transl Anim Sci 2018;3:384-392. [PMID: 32704809 PMCID: PMC7200528 DOI: 10.1093/tas/txy104]

Although chromium (Cr) feeding study results have been variable, our hypothesis was feeding a regimen that changed dosage over time would result in a larger positive response in growth performance and carcass characteristics. In Exp. 1, a total of 1,206 pigs (PIC 337 × 1050, initial BW 28.7 kg) were used with 27 pigs per pen and 9 pens per treatment. Diets were corn–soybean meal-dried distillers grains with solubles based and were fed in a five-phase feeding program. Treatments were arranged as a 2 × 2 + 1 factorial with a control diet containing no added Cr propionate (Kemin Industries Inc., Des Moines, IA), or diets with either 100 or 200 µg/kg added Cr during the grower (dietary phases 1 and 2) and/or finisher (dietary phases 3, 4, and 5) periods. During the grower period, ADG and G:F were similar among pigs fed the control or 100 µg/kg added Cr diets, but decreased in pigs fed 200 µg/kg Cr (quadratic, P ≤ 0.001). During the finisher period, pigs supplemented with 200 µg/kg added Cr had the greatest ADG and G:F (quadratic, P ≤ 0.019). Overall, increasing Cr had no effect on ADG or ADFI; but G:F was greatest (quadratic, P = 0.020) when pigs were fed 100 µg/kg of added Cr throughout. Carcass characteristics were not influenced by Cr dosage or feeding regimen. In Exp. 2, a total of 1,206 pigs (PIC 359 × 1050, initial BW 48.9 kg) were used with 27 pigs per pen and 15 pens per treatment. Diets were corn–soybean meal, dried distillers grains with solubles based and were fed in four phases. There were three dietary treatments: a diet with no added Cr for both grower (dietary phase 1 and 2) and finisher (dietary phase 3 and 4) periods, a diet with 200 µg/kg added Cr during the grower and 100 µg/kg added Cr during the finisher periods, or a diet with 200 µg/kg added Cr for both periods. Addition of 200 µg/kg Cr in both periods marginally increased (P < 0.10) ADG compared with pigs fed no added Cr. There was no evidence (P ≥ 0.523) of added Cr influencing overall ADFI and G:F. Percentage carcass yield was reduced (P = 0.018) when Cr was added at 200 µg/kg for both periods, with no evidence of differences (P ≥ 0.206) in other carcass characteristics. In summary, overall G:F was improved in Exp. 1, and ADG in Exp. 2, by added Cr, but there was no evidence that different feeding regimens will consistently result in improved performance. However, these data are consistent with the literature in that added Cr in growing-finishing pigs diets improves, albeit small, ADG or G:F.

Dietary supplementation of l-arginine and chromium picolinate in sows during gestation affects the muscle fibre characteristics but not the performance of their progeny

BACKGROUND

The present study investigated the effects of dietary supplementation of l-arginine and chromium picolinate (CrP) in sows during gestation on muscle fibre characteristics, performance and carcass characteristics of their progeny. Sixty healthy sows were randomly divided into four groups as a 2 × 2 factorial experiment design: one group received the control diet, another received the control diet + 10 g kg^-1 l-arginine, the third group received the control diet + 400 ppb CrP, and the fourth group received the control diet + 10 g kg^-1 l-arginine and 400 ppb CrP.

RESULTS

The results showed that sows fed the diet supplemented with CrP produced progeny with higher muscle fibre numbers at birth, weaning and slaughter compared to sows fed the control diet. For mean fibre areas, the same result was found at weaning. For progeny of sows fed diets supplemented with l-arginine, only higher muscle fibre numbers at slaughter was observed. Almost no differences were observed regarding average daily gains, average daily feed intake, gain-to-feed ratios, carcass and meat traits.

CONCLUSION

The results of the present study indicate that dietary supplementation of l-arginine and particularly CrP in sows during gestation alters muscle fibre numbers in their offspring, although not their performance or carcass characteristics. © 2017 Society of Chemical Industry.

Effects of Chromium Methionine Supplementation with Different Sources of Zinc on Growth Performance, Carcass Traits, Meat Quality, Serum Metabolites, Endocrine Parameters, and the Antioxidant Status in Growing-Finishing Pigs

This experiment was conducted to evaluate the effects of chromium methionine with/without zinc sulfate or zinc amino acid complex on the growth performance, carcass traits, meat quality, serum parameters, endocrine parameters, and antioxidant status of growing-finishing pigs. A total of 180 (32.0 ± 1.7 kg body weight, BW) crossbred pigs (Duroc × Landrace × Yorkshire) were used in a completely randomized design with three dietary treatments and 10 replicates per treatment (five pens of barrows and five pens of gilts with six pigs per replicate). Three treatments were corn-soybean meal-based diets supplemented with 100 mg Zn/kg from zinc sulfate (ZnSO₄), 100 mg Zn/kg from ZnSO₄ + 0.2 mg Cr/kg from chromium methionine complex (CrMet), or 50 mg Zn/kg from ZnSO₄ + 50 mg Zn/kg from zinc amino acid complex (ZnAA) + 0.2 mg Cr/kg from CrMet, respectively. The experiment lasted 105 days, of which was divided into three stages including phase 1 (30 to 50 kg BW), phase 2 (50 to 80 kg BW), and phase 3 (80 to 110 kg BW). Results showed that supplementation with CrMet and ZnAA improved (P < 0.05) the feed conversion of the pigs in phase 2, phase 3, and the overall experiment. Hot carcass weight, dressing percentage, and a longissimus dorsi muscle area were increased (P < 0.05) in pigs fed with diets supplemented with both CrMet and ZnAA compared with pigs fed with diets containing only ZnSO₄ (P < 0.05). There was also an increase (P < 0.01) pH_24 h in the longissimus dorsi muscle in pigs fed with diets supplemented with CrMet and ZnAA. The concentration of serum glucose in pigs fed with diets containing CrMet and ZnAA was decreased (P < 0.05) compared with that in pigs fed with the diet containing ZnSO₄. Supplementation with CrMet and ZnAA increased (P < 0.05) the circulating levels of insulin and decreased (P < 0.05) cortisol. There was an increase (P < 0.05) in total serum antioxidant capacity and Cu/Zn superoxide dismutase activity as well as a decrease (P < 0.05) in serum malondialdehyde concentrations in pigs fed with diets supplemented with CrMet and ZnAA compared with pigs fed with the diet supplemented only with ZnSO₄. In conclusion, supplementation of CrMet only or CrMet together with ZnAA improved feed conversion, carcass traits, and meat quality in the growing-finishing pigs.

Effect Of Chromium Nicotinate On Oxidative Stability, Chemical Composition And Meat Quality Of Growing-Finishing Pigs

The effect of different organic sources of Cr on growth, feed efficiency and carcass value is known but there is a lack of information between chromium nicotinate (CrNic) and pork quality. Therefore, purpose of this research was to investigate the effects of CrNic on chemical composition, quality and oxidative stability of pork meat. In the study, pigs of Large White breed (40 pcs) were used. The pigs were divided into two groups, namely the control and the experimental of 20 pcs with equal number of barrows and gilts. The pigs were fed the same diet which consisted of three feed mixtures applied at the different growth phases, from 30 - 45 kg OS-03, 45 - 70 kg OS-04 and 70 - 100 kg OS-05. The pigs were allowed ad libitum access to feed and water. The diet of experimental group was supplemented with 0.75 mg.kg-1 CrNic in the form of chromium-inactivated yeast Saccharomyces cerevisiae. The fattening period in pigs lasted from 30 to 100 kg. The chromium supplementation led to a significantly higher content of chromium in longissimus thoracis muscle (LT) of experimental pigs. In addition, the results showed a statistically significant difference (p ≤0.05) in retention of chromium in the LT, monounsaturated and omega-3 polyunsaturated fatty acids content in experimental group compared with control. Moreover, there was highly significant (p £0.05) difference in essential fatty acids, as well as in oxidative stability in 7 days, among the groups. The highly significant differences were also observed among sexes, namely in total water, protein and intramuscular fat contents, colour CIE b* in both times, and oxidative stability. However, physical-technological parameters (pH, drip loss, shear force and meat colour) were not affected when pigs were fed the supplement. On the whole, the positive effect of chromium nicotinate in most of investigated parameters may be beneficial not only for pork industry but also for consumers.

Effects of Graded Levels of Chromium Methionine on Performance, Carcass Traits, Meat Quality, Fatty Acid Profiles of Fat, Tissue Chromium Concentrations, and Antioxidant Status in Growing-Finishing Pigs

A 97-day feeding trial was conducted to investigate the effects of dietary chromium methionine (CrMet) on performance, carcass traits, meat quality, fatty acid profiles of fat, tissue chromium concentrations, and antioxidant status in growing-finishing pigs. A total of 180 crossbred pigs with a mean initial body weight (BW) 30.18 ± 0.28 kg were allotted to 5 treatments with 6 replicates per treatment and 6 pigs per pen in a randomized complete block design based on BW and sex. Treatments were added with 0 (control), 100, 200, 400, and 800 μg/kg chromium as CrMet. Blood samples were obtained from the anterior vena cava on days 97. Carcass characteristics, pork quality, and tissue chromium concentration data were collected from one pig per pen. The results indicated that supplemental CrMet did not significantly affect growth performance, carcass traits, or meat amino acid profiles. Chromium at 100, 400, and 800 μg/kg decreased drip loss but increased shear force (P < 0.05). Pigs fed 100 or 400 μg/kg had a higher 24-h pH than the control (P < 0.05). While meat color, muscle moisture, crude protein, or crude fat were not affected by CrMet. Supplemental 800 μg/kg chromium reduced C18:0 levels in belly fat (P < 0.05), and chromium supplementation increased cis-9, trans 11-conjugated linoleic acid levels linearly (P < 0.05). Dietary CrMet supplementation increased serum, kidney, and muscle chromium contents (P < 0.05) but did not affect liver chromium contents. Besides, tissue chromium concentrations were increased linearly with increased chromium dosage (P < 0.05). Chromium at 400 μg/kg increased serum glutathione peroxidase activities (P < 0.05), and chromium at 800 μg/kg decreased serum total antioxidant capacity levels (P < 0.05). Nevertheless, liver and kidney antioxidant status were not significantly affected by CrMet. These results indicated that dietary supplementation CrMet did not significantly influence growth and carcass traits, but improved meat quality at the expense of tenderness. Therefore, the long-term exposure to 800 μg/kg chromium affected fatty acid compositions and reduced serum antioxidant capacity.

Effects of Dietary Chromium Methionine on Growth Performance, Carcass Composition, Meat Colour and Expression of the Colour-related Gene Myoglobin of Growing-finishing Pigs

To investigate the effect of dietary chromium (Cr) as Cr methionine (CrMet) on growth performance, carcass traits, pork quality, meat colour and expression of meat colour-related genes in growing-finishing pigs, 189 crossbred Duroc×(Landrace×Yorkshire) growing-finishing pigs (male, castrated, average initial BW 74.58±1.52 kg) were selected and randomly allocated into four groups. Dietary treatments per kg of feed were as follows: 0 (CT), 0.3 mg/kg (T1), 0.6 mg/kg (T2) and 0.9 mg/kg (T3) Cr (in the form of CrMet; as-fed basis), and each treatment was replicated five times with 8 to 10 pigs per replicate pen. During the 28 d of the experiment, both the ADG and the ADFI increased linearly (p<0.05) as the level of dietary Cr increased. The F/G ratio decreased linearly (p<0.05). As dietary Cr increased, loin muscle areas (linear, p = 0.013) and average backfat thickness (linear, p = 0.072) decreased. Shear force (linear, p = 0.070) and Commission Internationale de I’Éclairage (CIE) redness (quadratic, p = 0.028) were increased. In addition, CIE Lightness (quadratic, p = 0.053) were decreased as dietary Cr increased. As dietary Cr increased, total myglobin (Mb) content (quadratic, p = 0.015) and the mb mRNA levels (quadratic, p = 0.046) in longissimus muscles of pigs were up-regulated. In conclusion, supplementation of dietary Cr improved growth and meat colour, but increased shear force and decreased IMF reduced palatability of longissimus muscles. Moreover, the increasing total Mb content and mb mRNA levels indicated that CrMet dietary supplementation may improve meat colour via up-regulating expression of the mb gene.

Effects of dietary chromium supplementation on performance, carcass characteristics, and meat quality of growing-finishing swine: a meta-analysis

Dietary Cr supplementation has potential to decrease fat and increase lean in carcasses of growing-finishing swine. However, effects of Cr supplementation on performance and economically important carcass and meat quality characteristics varied considerably among studies. Therefore, a meta-analysis was designed to quantitatively describe effects obtained in several independent studies. To accommodate differences in methodology among studies, standardized effect sizes (Hedges's g) were calculated for results from 31 studies, in which Cr was supplemented as complexes of Cr Met chelate, Cr nanocomposite, Cr nicotinate, Cr propionate, Cr tripicolinate, or Cr yeast in diets for growing-finishing swine. Summary statistics were calculated by frequentist fixed and random effects, and hierarchical Bayesian models. With characteristics related to carcass quality, observed heterogeneity (P < 0.10) could not adequately be explained in a meta-regression by differences in initial BW and amount of Cr supplemented. Random effects and Bayesian models to summarize effect sizes for these characteristics showed similar results. According to random effects models, dietary Cr supplementation decreased (P < 0.05) 10th-rib fat thickness (mean effect size = -0.479; 95% confidence intervals = -0.680 to -0.279; 24 studies; 59 comparisons), whereas percentage carcass lean (mean effect size = 0.614; 95% confidence intervals = 0.366 to 0.863; 22 studies; 52 comparisons) and LM area (mean effect size = 0.571; 95% confidence intervals = 0.364 to 0.778; 29 studies; 72 comparisons) increased. Average daily gain and G:F, which did not present heterogeneity, were improved by Cr supplementation, whereas no effects were detected in characteristics (CIE color, drip loss, cook loss, shear force) related to meat quality. Some publication, or other small-study bias, was evident in results on growth and feed efficiency. However, directions of mean effect sizes were not changed by application of the trim-and-fill method to correct for bias.

Effect of chromium picolinate supplementation on growth performance and meat characteristics of swine

The purpose of this study was to evaluate the effect of supplemental chromium (Cr) in the form of chromium picolinate (CrPic) on swine growth performance, meat quality, and protein deposition in skeletal muscle. Forty-eight piglets were divided into three groups randomly, fed with three different dietary levels of Cr (common basal feedstuff supplemented with a dose of 1.61 μg/g or 3.22 μg/g CrPic, which corresponded to 0.2 and 0.4 μg/g Cr). Results indicated that during the growing period (1-35 days), pigs fed with the diet supplemented with CrPic showed no improvement in body mass, average daily gain (ADG), feed consumption, or feed conversion rate (FCR) (P > 0.05). During the finishing period, a supplementary dose of 0.2 μg Cr/g improved daily weight gain significantly (P < 0.05), while the situation had no significance with 0.4 μg Cr/g (P > 0.05) supplemented. For the entire growing-finishing period, body mass increased by 3.86%, ADG rose by 6.08%, and the FCR decreased by 3.30%; levels of total muscular pigment and that in the ribeye areas significantly improved (P < 0.05) when supplementation with 0.2 μg Cr/g (P < 0.05) was employed. However, there were no significant changes when supplemented with 0.4 μg Cr/g. While there were no changes in yield of carcass, back fat, water holding capacity, or levels of muscular crude protein and fat (P > 0.05) in treatment, the ratio of fat-lean and RNA/DNA increased significantly supplemented with 0.2 μg Cr/g (P < 0.05), but there were no significance with 0.4 μg Cr/g supplementation. In addition, the muscular levels of cholesterol had slightly decreased and the content of DNA in skeletal muscle showed no marked changes with 0.2 or 0.4 μg/g Cr supplementation. In conclusion, the present results suggested that dietary Cr supplementation in the dose of 0.2 μg/g could promote the growth performance, carcass characteristics, and protein deposition.

Níveis de cromo orgânico em rações para frangos de corte mantidos sob estresse por calor no período de um a 42 dias de idade

Avaliou-se o efeito da suplementação de cromo sobre o desempenho e o rendimento de cortes de frangos, mantidos em ambiente de alta temperatura, no período de um a 42 dias de idade. Foram utilizados 400 frangos de corte, machos, da linhagem Cobb, em um delineamento experimental inteiramente ao acaso, com cinco tratamentos, 0, 350, 700, 1.050 e 1.400ppb de cromo na ração, oito repetições e 10 aves por repetição. Nos períodos de um a 21 e de um a 42 dias de idade, não houve influência dos tratamentos sobre o ganho de peso, o consumo de ração e a conversão alimentar das aves, mas observou-se que o consumo de cromo aumentou de forma linear. Os tratamentos não influenciaram os pesos absoluto e relativo de nenhum dos cortes, peito, coxa e sobrecoxa, avaliados aos 42 dias de idade. A suplementação de até 1.400ppb de cromo na ração não influenciou o desempenho e o rendimento de cortes nobres de frangos de corte mantidos em estresse por calor, no período de um a 42 dias de idade.