61 Effect of Whey Protein-Enriched Water on Performance and in Vivo Carcass Measurements in Fattening Merino Lambs Hüseyin Eseceli 1* • Selim Esen 2 • Mehmet Keten 3 • Ayşen Altıner 4 • Tanay Bilal 5 1* Kastamonu University, Faculty of Veterinary, Department of Animal Nutrition and Nutritional Diseases, Kastamonu/Turkey. Bandirma Onyedi Eylül University, Faculty of Health Science, Department of Nutrition and Dietetics, Balıkesir/Turkey. E-mail: heseceli@gmail.com 2 Balikesir Directorates of Provincial Agriculture and Forestry, Republic of Turkey Ministry of Agriculture and Forestry, Manyas, Balikesir/Turkey. E-mail: selim_esen01@hotmail.com 3 Balikesir Directorates of Provincial Agriculture and Forestry, Republic of Turkey Ministry of Agriculture and Forestry, Balikesir/Turkey. E-mail: mehmetketen@gmail.com 4 Istanbul University-Cerrahpasa, Faculty of Veterinary, Department of Biochemistry, stanbul/Turkey. E-mail: altinera@istanbul.edu.tr 5 Istanbul University-Cerrahpasa, Faculty of Veterinary, Department of Animal Nutrition and Nutritional Diseases, stanbul/Turkey. E-mail: tanbilal@istanbul.edu.tr A R T I C L E I N F O Article History: Received: 28.08.2020 Accepted: 30.11.2020 Available Online: 04.02.2021 Keywords: WHEY Loin Eye Depth Fat Thickness Fattening A B S T R A C T Whey, a by-product of the dairy industry, is primarily used for protein and energy sources in livestock diets due to its high nutritional value, which equivalent to grain corn and barley. In the current study, whey powder was added to lamb drink water to evaluate its effects on performance and in vivo carcass measurements. Twenty-four non-castrated healthy male Merino lambs with an average of 3 months weaning age and 23.44 ± 0.62 kg (mean ± SE) initial live weight (LW) used in this study. Lambs were randomly allocated into two trial groups according to their LW and adapted to concentrate and whey protein-enriched water. The total period of trial was 45 days, with 15 days adaptation and 30 days for data collection. Lambs were housed in a group and received ad libitum wheat straw, lamb-grower feed, and water (enriched with whey protein or not). There were no significant differences observed in treatment groups for total weight gain (TWG, P > 0.05). On the other hand, the whey-treated group's average TWG value is 8.60% higher than the control group. Besides, the differences between initial and final loin eye depth (LED) was 4.7 times higher in the whey group than the control group (0.28 cm vs. 0.06 cm). Also, no significant differences were observed between the trial group for fat thickness (P > 0.05). Obtained results from the present study indicated that using whey powder even in animal drinks improved TWG and LED in the fattening period. Please cite this paper as follows: Eseceli, H., Esen, S., Keten, M., Altıner, A. and Bilal, T. (2021). Effect of Whey Protein-Enriched Water on Performance and in Vivo Carcass Measurements in Fattening Merino Lambs. Alinteri Journal of Agriculture Sciences, 36(1): 61-65. doi: 10.47059/alinteri/V36I1/AJAS21010 Introduction There has been a great interest in using by-products as an alternative feed source to decrease feeding costs for ruminants worldwide. One of the most important and highly nutritious by-products is whey, classified in unusual by- products. *Corresponding author: heseceli@gmail.com ORCID: 0000-0002-5912-5479 Whey, a by-product of the dairy industry, is utilized well when used in animal diets in different forms such as liquid, condensed, or dried whey or whey products (Ahlam, 2016). Because of its high protein and energy contents, whey is primarily used for protein and energy sources in livestock diets. Also, the broad regional diversity of whey makes itself a valuable source for reducing the cost of diets in neighboring sheep farmers contributing to the reduction of environmental contamination (Primo, 2010; Palmieri et al., 2017; Pinheiro Rogério et al., 2019). It has been Alinteri J. of Agr. Sci. (2021) 36(1): 61-65 e-ISSN: 2587-2249 info@alinteridergisi.com http://dergipark.gov.tr/alinterizbd http://www.alinteridergisi.com/ DOI:10.47059/alinteri/V36I1/AJAS21010 RESEARCH ARTICLE