Assessment of vitamin A requirement of gosling in 0-28 d based on growth performance and bone indexes

Tibial Damage Caused by T-2 Toxin in Goslings: Bone Dysplasia, Poor Bone Quality, Hindered Chondrocyte Differentiation, and Imbalanced Bone Metabolism

T-2 toxin, the most toxic type A trichothecene, is widely present in grain and animal feed, causing growth retardation and tissue damage in poultry. Geese are more sensitive to T-2 toxin than chickens and ducks. Although T-2 toxin has been reported to cause tibial growth plate (TGP) chondrodysplasia in chickens, tibial damage caused by T-2 toxin in geese has not been fully demonstrated. This study aims to investigate the adverse effects of T-2 toxin on tibial bone development, bone quality, chondrocyte differentiation, and bone metabolism. Here, forty-eight one-day-old male Yangzhou goslings were randomly divided into four groups and daily gavaged with T-2 toxin at concentrations of 0, 0.5, 1.0, and 2.0 mg/kg body weight for 21 days, respectively. The development of gosling body weight and size was determined by weighing and taking body measurements after exposure to different concentrations of T-2 toxin. Changes in tibial development and bone characteristics were determined by radiographic examination, phenotypic measurements, and bone quality and composition analyses. Chondrocyte differentiation in TGP and bone metabolism was characterized by cell morphology, tissue gene-specific expression, and serum marker levels. Results showed that T-2 toxin treatment resulted in a lower weight, volume, length, middle width, and middle circumference of the tibia in a dose-dependent manner (p < 0.05). Moreover, decreased bone-breaking strength, bone mineral density, and contents of ash, Ca, and P in the tibia were observed in T-2 toxin-challenged goslings (p < 0.05). In addition, T-2 toxin not only reduced TGP height (p < 0.05) but also induced TGP chondrocytes to be disorganized with reduced numbers and indistinct borders. As expected, the apoptosis-related genes (CASP9 and CASP3) were significantly up-regulated in chondrocytes challenged by T-2 toxin with a dose dependence, while cell differentiation and maturation-related genes (BMP6, BMP7, SOX9, and RUNX2) were down-regulated (p < 0.05). Considering bone metabolism, T-2 toxin dose-dependently and significantly induced a decreased number of osteoblasts and an increased number of osteoclasts in the tibia, with inhibited patterns of osteogenesis-related genes and enzymes and increased patterns of osteoclast-related genes and enzymes (p < 0.05). Similarly, the serum Ca and P concentrations and parathyroid hormone, calcitonin, and 1, 25-dihydroxycholecalciferol levels decreased under T-2 toxin exposure (p < 0.05). In summary, 2.0 mg/kg T-2 toxin significantly inhibited tibia weight, length, width, and circumference, as well as decreased bone-breaking strength, density, and composition (ash, calcium, and phosphorus) in 21-day-old goslings compared to the control and lower dose groups. Chondrocyte differentiation in TGP was delayed by 2.0 mg/kg T-2 toxin owing to cell apoptosis. In addition, 2.0 mg/kg T-2 toxin promoted bone resorption and inhibited osteogenesis in cellular morphology, gene expression, and hormonal modulation patterns. Thus, T-2 toxin significantly inhibited tibial growth and development with a dose dependence, accompanied by decreased bone geometry parameters and properties, hindered chondrocyte differentiation, and imbalanced bone metabolism.

Performance and bone characteristics of broilers fed diets supplemented with vitamin A at different concentrations

This work evaluated the influence of vitamin A on performance, organ weight, and bone and skin characteristics in broilers (Cobb 500) at 21 and 42 days of age. A total of 1920 chickens were distributed in a randomised design, considering six vitamin A supplementation levels (0, 6000, 16,000, 26,000, 36,000, and 46,000 IU kg-1 ), with 16 replicates and 20 chickens per experimental unit, established due to rising the range of vitamin levels observed in the literature to evaluate the effect of vitamin A on broilers. At 22 days, half of the replicates from each treatment continued receiving the initial diet, and the other eight repetitions received diets without vitamin A (0 IU kg-1 ) until 42 days. The level of vitamin A influenced feed intake (FI) and body weight gain (BWG) until 21 days for all treatments. Broilers at 21 days of age had a more significant BWG at a vitamin A supplementation level of 28,209 IU kg-1 . At 42 days, vitamin A influenced the BWG and FI of broilers at treatments that were not supplemented after 21 days. Treatments supplemented up to 42 days showed quadratic responses to vitamin A for BWG, FI, and feed conversion. The vitamin A levels influenced the relative weights of the small intestine, pancreas, gizzard, abdominal fat, Seedor index, and breaking strength at 42 days, where the adequate supplementation of vitamin A improved these characteristics in broilers. Vitamin A supplementation from 22 to 42 days old did not affect broiler performance. An increased BWG was obtained when vitamin A supplementation occurred until 42 days, with supplementation of 29,375 IU kg-1 and a lower response of feed conversion with the addition of 27,775 IU kg-1 .

Morphometric Analysis of Developmental Alterations in the Small Intestine of Goose

In this study, a morphometric analysis of morphological changes in the layers of the small intestine (duodenum and jejunum) and liver occurring during the hatching period (week 0) and postnatal development (weeks 1, 3, 6, and 8) was performed in geese. For this purpose, the staining of samples obtained from tissues collected from geese after culling was carried out. Staining was performed using the Goldner method to visualize all layers of the intestine for morphometric measurements. Our analysis focused mainly on traits such as the thickness of the mucosal, submucosal, and muscular layers, as well as traits related to intestinal absorption, such as the height and width of intestinal villi and crypts. Additionally, we also took into account the number of mononuclear and binucleate hepatocytes and other cells present in the liver. After analyzing the results, an increase in most traits was found during the development of the animals, with slight differences between the sections of the duodenum and jejunum. An interesting phenomenon was also noticed-the greatest increase in most traits was observed between the 3rd and 6th week of life, which coincides with the time of feed change. We hope that our work will highlight how important the digestive system is for birds because research on this topic is limited.

Pros and Cons of Dietary Vitamin A and Its Precursors in Poultry Health and Production: A Comprehensive Review

Vitamin A is a fat-soluble vitamin that cannot be synthesized in the body and must be obtained through diet. Despite being one of the earliest vitamins identified, a complete range of biological actions is still unknown. Carotenoids are a category of roughly 600 chemicals that are structurally related to vitamin A. Vitamin A can be present in the body in the form of retinol, retinal, and retinoic acid. Vitamins are required in minute amounts, yet they are critical for health, maintenance, and performing key biological functions in the body, such as growth, embryo development, epithelial cell differentiation, and immune function. Vitamin A deficiency induces a variety of problems, including lack of appetite, decreased development and immunity, and susceptibility to many diseases. Dietary preformed vitamin A, provitamin A, and several classes of carotenoids can be used to meet vitamin A requirements. The aim of this review is to compile the available scientific literature regarding the sources and important functions, such as growth, immunity, antioxidant, and other biological activities of vitamin A in poultry.