نوع مقاله : مقاله پژوهشی
نویسندگان
1 سازمان تحقیقات، آموزش و ترویج کشاورزی، موسسه تحقیقات علوم دامی کشور، کرج. ایران.
2 عضو هیئت علمی دانشکده کشاورزی دانشگاه پیام نور تهران، تهران. ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This study was conducted to study the effects of different levels of hydrolyzed hoof meal, as a dietary ingredient, on the performance, carcass characteristics, and jejunum histology of broiler chickens during the finisher phase with pelleted diets. Six hundred Ross 308 male broiler chicks, with equal average weight, were randomly assigned to four experimental groups in a completely randomized design, with five replicates per group and 30 birds per replicate, from 25 to 44 days of age. The experimental treatments included: (1) a control diet (without hoof meal), (2) a diet containing 2% hoof meal, (3) a diet containing 4% hoof meal, and (4) a diet containing 6% hoof meal. The results of performance showed that, compared to the control diet use of 2% and 6% of hoof meal reduced the cost of feed consumed per kilogram of live weight of chicks by improving the feed conversion ratio of the bird between 35 and 44 days of age. Relative carcass and thigh weight were increased by the dietary inclusion of 6% hydrolyzed hoof meal compared to the control (P < 0.05). Histological analysis revealed that jejunal crypt depth was significantly decreased in broilers fed 2% hydrolyzed hoof meal compared with the control diet (P < 0.05). This study demonstrated that feeding dietary hydrolyzed hoof meal during the finisher phase positively influenced broiler carcass traits and jejunum histology without negatively impacting performance.
کلیدواژهها [English]
Extended Abstract
Introduction
The global shortage of protein resources, alongside a heavy reliance on imports and the associated high costs, has driven research efforts toward identifying alternative protein sources for use in poultry diets, either as partial or complete replacements for conventional protein sources. Since the early 20th century, slaughterhouse by-products derived from livestock and poultry have been incorporated as feed ingredients in poultry diets across various regions worldwide. These by-products, sourced from the processing of domesticated animals, represent a significant reservoir of natural resources that, when appropriately processed, can be utilized effectively in animal nutrition. Additionally, their utilization contributes to reducing the organic carbon footprint associated with livestock production. Despite the recognized potential of slaughterhouse by-products, there is currently no documented research on the effects of incorporating hydrolyzed bovine hoof meal into broiler chicken diets, particularly regarding its impact on growth performance and jejunal histology. Consequently, this study aimed to evaluate the impact of different inclusion levels of hydrolyzed bovine hoof meal in pelleted diets during the finisher phase (25 to 44 days of age) on performance metrics, carcass characteristics, and jejunal histological indices in broiler chickens.
Materials and Methods
A total of 600 male broiler chickens (Ross 308) were utilized in a completely randomized design to evaluate the effects of hydrolyzed hoof meal on broiler performance, carcass traits, and jejunal morphology. The birds were distributed into 4 experimental treatments with 5 replicates per treatment and 30 birds per replicate, covering the finisher phase from 25 to 44 days of age. The experimental treatments were as follows: (1) a control diet without hydrolyzed hoof meal, (2) a diet containing 2% hydrolyzed hoof meal, (3) a diet containing 4% hydrolyzed hoof meal, and (4) a diet containing 6% hydrolyzed hoof meal. The preparation of hydrolyzed cattle hoof powder involved processing slaughterhouse-derived cattle hooves using steam hydrolysis at a pressure of 9 bar and a temperature of 150°C for one hour. The hydrolyzed material was then ground into a powder suitable for inclusion in poultry diets. To evaluate the performance of the broilers, average daily feed intake (ADFI) and average daily weight gain (ADWG) were recorded for each experimental unit during three periods: 25 to 34 days, 34 to 44 days, and 25 to 44 days of age. The feed conversion ratio (FCR) was calculated by adjusting for daily mortality and using the Hen-day method. On day 44, all chickens were individually weighed and slaughtered to assess carcass characteristics. The relative weights of the carcass, breast, thighs, liver, proventriculus, gizzard, spleen, bursa of Fabricius, heart, and pancreas were measured. Additionally, the weight and length of the gastrointestinal tract and small intestine, as well as abdominal fat weight, were recorded. For jejunal morphology analysis, sections of the jejunum were prepared, and villus height, villus width, crypt depth, and the villus height-to-crypt depth ratio were measured according to approved method. The data collected in this experiment were analyzed using the General Linear Model (GLM) procedure in SAS software. Treatment means were compared using Tukey's test, with statistical significance set at a probability level of 0.05 (P < 0.05).
Results and Discussion
The performance data demonstrated a statistically significant improvement in feed conversion ratio (FCR) and feed cost per kilogram of live weight in broiler chickens fed diets containing 2% and 6% hydrolyzed bovine hoof meal compared to the control group during the 35 to 44-day period (P < 0.05). However, no significant differences were observed in average daily feed intake (ADFI) or average daily weight gain (ADWG) between the experimental treatments (P > 0.05). The results suggest that hydrolyzed hoof meal, due to its effective chemical composition and high nutritional value, can be incorporated into poultry diets at higher inclusion levels without adversely affecting growth performance. This feed ingredient is competitive with conventional corn-soybean meal diets, offering a more balanced energy-to-protein ratio that is critical for maximizing poultry performance. Carcass characteristic analysis revealed that broilers fed a diet containing 6% hydrolyzed hoof meal exhibited a significant increase in carcass yield and thigh meat yield compared to those fed the control diet (P < 0.05). These findings align with previous research indicating that keratin-rich by-products from slaughterhouses, including feathers, hooves, and horns, when appropriately processed, are excellent sources of crude protein, with concentrations ranging from 69.5% to 88.6%, primarily in the form of keratin. The incorporation of hydrolyzed bovine hoof meal into poultry diets not only enhances carcass traits but also provides a sustainable alternative to conventional protein sources, contributing to the efficient utilization of slaughterhouse by-products in livestock nutrition. In addition to supporting muscle growth, slaughterhouse by-products can serve as significant energy sources for poultry. The inclusion of graded levels of hydrolyzed bovine hoof meal in broiler diets did not result in significant changes in the relative weights of internal organs or in the relative weight and length indices of specific gastrointestinal tract segments, including the duodenum, jejunum, ileum, and cecum (P > 0.05). While the relative weight of abdominal fat in broilers fed diets containing hydrolyzed hoof meal was lower compared to the control group, this reduction was not statistically significant (P > 0.05). Previous research on keratin-based products has shown their potential to reduce fat accumulation in the body. For instance, keratin-derived compounds such as creatine-pyruvate have been found to enhance the activity and expression of CPT-I and PPAR-α genes, which are key regulators of fatty acid beta-oxidation, in both liver and adipose tissues. This upregulation promotes an increased rate of beta-oxidation and reduces fat storage in the body. Histomorphological analysis of the jejunum revealed that broilers fed a diet containing 2% hydrolyzed hoof meal exhibited a significant reduction in crypt depth compared to the control and 6% hoof meal diets (P < 0.05). These findings suggest that keratin-based compounds, which are rich in protein and essential amino acids such as methionine, arginine, and glycine, play a critical role in stimulating intestinal mucosa development and enhancing cell proliferation in the crypt-villus axis. This process ultimately increases both the number and size of villi, thereby improving the digestive and absorptive capacities of the intestinal tract in poultry.
Conclusions
The findings of this study indicate that the inclusion of hydrolyzed bovine hoof meal in the diets of broiler chickens during the finisher phase improved specific carcass traits without negatively impacting overall performance. Additionally, the diet containing 2% hydrolyzed hoof meal significantly enhanced the absorptive capacity of the jejunum compared to the control diet. These results highlight the potential of hydrolyzed hoof meal as a viable feed ingredient for broiler chickens. Further research is recommended to explore its broader applications and optimize its inclusion levels in poultry diets.
This article contains all the data that were created or evaluated during the research.
The authors would like to acknowledge Andisheh Sazan Sanat Feed Company for providing the hydrolyzed poison powder supplement, as well as the Animal Science Research Institute and the Department of Nutrition Research for providing the necessary facilities and husbandry resources required for the conduct of this research.
The author declares no conflict of interest.
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