The aim of this study was to investigate the impact of additives containing organic acids, herbal extracts, and prebiotics to whole milk on the developmental performance and several faecal and blood parameters of Holstein calves during the suckling period. A total of 40 one-day-old Holstein calves were divided randomly categorized into two groups of 20 (10 males and 10 females). For the first three days, both groups were provided with five litres of colostrum daily. Starting from the fourth day, the first group (control) received whole milk, while the second group (NCA) was given milk with a commercial additive of 5 g/L of whole milk. The calves had access to starter feed and water ad libitum. Results indicated the body weight and red blood cell counts of calves in the NCA group showed a substantial increase during the first four weeks, while the occurrence of diarrhoea decreased, compared to the control group. However, no marked differences between the control and NCA groups in terms of intake of concentrate feed, feed conversion ratio, body weight gain, levels of white blood cells, haemoglobin, haematocrit, aspartate aminotransferase, phosphorus, gamma-glutamyl transferase, glucose, calcium, creatinine, cholesterol, triglycerides, faecal levels, or days with diarrhoea were noted. Consequently, it was concluded that adding commercial additives to whole milk had a positive effect on the early development of the digestive system of calves, substantially increasing their body weight in the first four weeks of life and therefore making them more resistant to diseases in this critical period.

This study was conducted to determine the effects on performance, egg quality parameters and some serum profiles of vitamin E, thyme and rosemary extracts that were added to laying hen feeds. One hundred twelve 48-week-old Bovans-genotype white laying hens were used in the research. In the study, hens were randomly divided into four groups, each comprising of four replicates of seven hens. The first group was fed with the basal diet as a control. The other three groups were fed diets with 200 mg/kg vitamin E, with 1000 mg/kg thyme, and with 1000 mg/kg rosemary for eight weeks. As a result, vitamin E increased egg production statistically compared with feeds with plant extracts. Thyme-supplemented feed increased egg weight significantly. However, it reduced egg production. Rosemary supplementation generated profit by reducing the feed intake, but had a negative effect by reducing egg weight and egg production. The cholesterol level in the blood serum decreased with thyme supplementation. In addition, blood triglyceride level decreased at a statistically significant level with the supplementation of both thyme and rosemary. In the light of these results, it can be said that the supplementation of vitamin E, thyme and rosemary extracts has a positive effect on some performance parameters and animal health. Since healthier products are obtained from healthy animals, the use of these natural additives in laying hen feeds could be recommended after dose trials.

ABSTRACT In this study, the effects of the supplementation of natural and synthetic antioxidant additives in layer diets on egg weight loss, yolk lipid peroxidation (TBARS values) and fatty acid composition of eggs stored at different temperatures and duration were evaluated. In total, 112 48- weeks-old Bovans White layers were randomly allotted to four dietary treatments with four replicates of seven birds each. The treatments consisted of a control diet, containing no additives, and diets with the inclusion of 200 mg synthetic vitamin E/kg, 1000 mg thyme extract/kg and 1000 mg rosemary extract/kg. Dietary treatments did not influence (p>0.05) relative weight loss of eggs stored for 14, 28, and 56 days, except for those from rosemary-fed hens stored at room temperature on d 42, which were significantly lighter than the eggs from vitamin E- and thyme-fed hens (p<0.001). Relative egg weight loss was significantly higher (p<0.001) when stored at room temperature than under refrigeration, independently of storage time. In eggs stored at room temperature, yolk TBARS values were significantly lower (p<0.001) in the eggs of vitamin E-fed hens, whereas no influence (p>0.05) of dietary treatment on yolk TBARS values were detected in refrigerated eggs. The inclusion of the synthetic and both natural antioxidants in layer diets significantly reduced stearic acid (C18: 0) level in the egg yolk. In addition, only natural antioxidants significantly increased yolk levels of palmitoleic acid (C16: 1) and vaccenic acid (C18: 1n7). The results of the present study showed that adequate storage temperature was more effective in improving egg shelf life than feeding layers synthetic or natural antioxidant additives. However, the positive effects of the evaluated natural antioxidants on yolk fatty acid composition suggest their supplementation to layer diets may provide health benefits to the consumer.