Advances in Animal and Veterinary Sciences May 2023 | Volume 11 | Issue 5 | Page 795 INTRODUCTION I ndonesia is a country that has a very high diversity of local chickens. In addition to producing meat and eggs, Indonesia local chickens are also often used as fighting chickens, ornamental chickens, superior breed chickens, and singing chickens with a different crowing sound from other chickens. ere are several types of singing chick- ens that have long been developed and are popular with the public, such as Pelung Chicken in West Java, Bekisar Chicken in East Java, Ketawa Chicken in South Sulawesi and Kokok Balenggek Chicken (KBC) in West Sumatra. KBC is a germplasm that must be preserved, this chicken is a cross between the Red Junglefowl (Gallus gallus) and the local chicken (Rusfidra, 2004). e KBC population is suspected of continuing to decline. e latest report by Abbas et al. (2014) stated that the adult KBC population counted 189 and 271 young male chickens in the in-situ area and the highest population was in Kenagarian Rang- kiang Luluih, Tigo Lurah District, Solok Regency, West Sumatra. Mukhdi et al. (2011) noted that the migration of KBC out of the area reached 30 individuals every month and was one of the reasons for the decline in the KBC population. erefore, conservation is important to in- Research Article Abstract | is study aims to evaluate the characteristics of fresh semen of the Kokok Balenggek chicken (KBC) as well as fertility, fertile period, and sex ratio as a result of artificial insemination with variations in spermatozoa con- centrations. Semen from 12 KBC was collected and evaluated to determine their characteristics (motility, viability, concentration, and abnormalities). Semen showing motility >70% was diluted into 500µl of Ringer’s lactate solution with various concentrations of spermatozoa, namely 50×10 6 , 100×10 6 , and 150×10 6 . Fertile period and fertility were evaluated by inseminating spermatozoa in hens. Eggs were collected two days after insemination and observed for em- bryo development using the candling method. Observation of fresh semen of the KBC showed that macroscopically the semen of the KBC was white, thick, and had a volume of 415 ± 218.08 µl. While the results of the microscopic evaluation showed that the semen quality of the KBC was a positive mean mass movement of 2 (++), spermatozoa motility was 79.71 ± 2.91 %, spermatozoa concentration was 2432.34 ± 668.08×106, spermatozoa viability was 93.06 ± 5.61 % and spermatozoa abnormality was 15.67 ±7.07 %. Insemination using a concentration of 150×10 6 spermatozoa significantly (P<0.05) increased fertility (50.87±4.92 %) and fertile period (6.05±4.75 days) and did not affect the sex ratio. Combination research on spermatozoa concentrations and insemination time intervals needs to be carried out to optimize fertility and the fertile period of spermatozoa in KBC. Keywords | KBC, Artificial insemination, Fertility, Fertile period, Sex ratio. JASWANDI, ANANDA*, RUSFIDRA, KUSNADIDI SUBEKTI, HARIF GUSDINAL, RAZIAH SRI WAHYUNI, FAHMI ARIANSYAH CANIAGO Fertility Rate, Fertility Period, and DOC Sex Ratio of Kokok Balenggek Chicken after Artificial Insemination Received | January 04, 2023; Accepted | February 20, 2023; Published | April 01, 2023 *Correspondence | Ananda, Department of Livestock Production Technology, Faculty of Animal Science, Universitas Andalas, Indonesia; Email: ananda@ansci. unand.ac.id Citation | Jaswandi, Ananda, Rusfidra, Subekti K, Gusdinal H, Wahyuni RS, Caniago FA (2023). Fertility rate, fertility period, and doc sex ratio of kokok baleng- gek chicken after artificial insemination. Anim. Vet. Sci. 11(5): 795-801. DOI | http://dx.doi.org/10.17582/journal.aavs/2023/11.5.795.801 ISSN (Online) | 2307-8316 Copyright: 2023 by the authors. Licensee ResearchersLinks Ltd, England, UK. is article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY ) license (https://creativecommons. org/licenses/by/4.0/). Department of Livestock Production Technology, Faculty of Animal Science, Universitas Andalas, Indonesia.