Reproductive patterns of the yak. I. Reproductive phenomena of the female yak

Yu, Sijiu; Huang, Yufeng; Chen, B.X.

doi:10.1016/s0007-1935(05)80042-9

Cited by 34 publications

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“…Many studies have shown that pregnancy rates are above 70% if female yak are mated with yak bulls [1,5,17,18]. However, when the yak female is inseminated (naturally or artificially) with semen from Bos taurus or Bos indicus, the pregnancy rate falls [3,5].…”

Section: Discussionmentioning

confidence: 99%

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Yin

Chen

et al. 2009

Journal of Reproduction and Development

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Abstract. The purpose of this study was to investigate fertilization ability and embryo development to the blastocyst stage after reciprocal in vitro fertilization (IVF) between yak and cattle in an attempt to clarify the problem of low conception rate after mating yak females with cattle bulls. In vitro-matured (IVM) cattle and yak oocytes were inseminated with either Holstein or yak spermatozoa, and after an 18-h of coincubation period, a proportion of the oocytes was fixed and examined for sperm penetration, polyspermy and male pronuclear formation. The remaining oocytes were cultured in vitro and evaluated for cleavage and blastocyst formation rates. The percentage of IVM oocytes penetrated by spermatozoa ranged from 78.5 to 90.5%, and the formation of one or two pronuclei and the incidence of polyspermy did not differ among the different combinations. The cleavage and blastocyst rates were not affected by the species of the sperm, but they were affected by the species of the oocytes (P<0.05), with cattle oocytes having a higher (P<0.05) cleavage and blastocyst rates (69.9 and 31.3%) than yak oocytes (62.7 and 11.5%). The blastocyst formation rate was calculated from the cleaved zygotes. The interaction between sire and oocytes species (P<0.05) influenced blastocyst formation rate, with the highest blastocyst rate occurring in cattle oocytes fertilized with yak spermatozoa (36.5%) and the lowest rate occurring in yak oocytes fertilized with yak spermatozoa (9.4%). The effect of heterosis was apparent at the blastocyst stage, but there was a large reciprocal difference in blastocyst production between crosses. It was concluded that the low conception rate that results from crossing yaks with cattle is not due to either a speciesspecific block of fertilization or the developmental competence of the early stage embryo. Key words: Cattle, Early development, Embryos, In vitro fertilization (IVF), Yak (J. Reprod. Dev. 55: [480][481][482][483] 2009) he yak is one of the world's most remarkable domestic animals -a herbivore living on the "roof of the world", in and around the Himalayas and further north at altitudes ranging from 2500 to 5500 m with no frost-free period and mostly above the tree line. They are very important to local people for meat, milk and draft power given that few other animals survive in these areas. However, their production traits are inferior to those of improved cattle (Bos taurus) breeds [1,2].Interest in the commercial use of local cattle × yak hybrids has existed for at least 3000 years. During this time, attempts have been made to improve meat and milk production (quoted from Wiener et al. [1]). A number of systematic studies carried out from 1950s to 1990s have examined the meat and milk performance of hybrids of yak derived from both natural mating and artificial insemination using semen from exotic breeds of cattle such as the Holstein, Simmental, Hereford and Shorthorn. The results have shown that F1 hybrids from dairy cattle breeds produce 100-300% more milk than the yak [3,4]. ...

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Section: Discussionmentioning

confidence: 99%

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Yin

Chen

et al. 2009

Journal of Reproduction and Development

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“…Puberty usually occurs in the second to fourth warm season after birth, that is, between thirteen and thirty-six months of age. The estrous cycle is approximately twenty days and estrus usually lasts less than two days, although a wide range of values has been reported for both the cycle length and duration of estrus (Yu, Huang and Chen 1993;Zhao 2000b;Zhang 2000). Females are usually mated for the first time when they are three to four years of age.…”

Section: Yak Reproductionmentioning

confidence: 99%

Transhumant Pastoralism in Yak Production in the Lower Mustang District of Nepal

Degen¹,

Kam²,

Pandey³

et al. 2007

Nomadic Peoples

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There are thirty yak herd owners, all men and mainly Thakalis, between Jomsom and Lete in Lower Mustang. Transhumance is used in herding yaks, which migrate seasonally between winter pastures at about 3,000-4,000 metres and summer pastures at about 4,000-5,000 metres above sea level. Absentee herd ownership, in which shepherds (usually members of a non-Thakali ethnic group) herd only yaks and do not own any animals themselves, is common. Yaks are raised primarily for meat and milk, though substantial income is realized from selling blood during two blood-drinking ceremonies and from selling yaks as pack animals. Milk is used for products such as butter/ghee and a dry, hard curd cheese (chhurpi), which are mainly sold but also used for home consumption and for making 'salty butter tea'.Yak wool has little commercial value today but is used to make rope and tents. Yak owner estimations of how much of their income is derived from their herds range widely between 10 percent and 90 percent, but average about 50 percent. Additional income is made from the sale of seasonal crops, in particular apples, potatoes, maize, millet and barley that are produced on the owners' land. Owners also raise chickens, cows, buffalo, oxen, horses and goats. Two of the herd owners owned hotels that were run by their families. In this study, annual earnings from yaks totalled approximately Nepalese Rupees (N.Rs) 72,780 and total income for the herd owner was about N.Rs 145,560 (U.S. $2,079).We concluded that for these herd owners, yak raising is not a subsistence economic activity but rather part of a market economy based on speculative investments and accumulation. Moreover, yak production is a very high-risk enterprise as disasters can decimate large proportions of a herd quickly.

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“…As a special plateau mammal, there are many studies on their reproductive performance, including reproductive organ structures [1–4], hormone regulation [5–8] and adaptability. Studies on the adaptability of yak are mostly concentrated on the respiratory system [9–11], circulatory system [12–14] and immune system [15,16], including the histological structure, ultrastructure and distribution of some factors such as VEGF, HIF and CX43.…”

Section: Introductionmentioning

confidence: 99%

The histological characteristics, age-related thickness change of skin, and expression of the HSPs in the skin during hair cycle in yak (Bos grunniens)

et al. 2017

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ObjectiveThis experiment was conducted to study the histological characteristics, age-related thickness changes, and expression of HSPs in the skin of yak.MethodsA total of 20 yaks (10 males and 10 females) were used. Different regions of the normal skin of three different ages (newborn, half-year-old and adult) of yaks were harvested for histological study and thickness measurement. Biopsy samples were taken from the scapula regions of the skin from the same five approximately 1-year-old yaks during the hair cycle (telogen, anagen and catagen). RT-PCR, western blot and immunohistochemistry methods using the mRNA and protein levels were used to detect the expression of HSP27, HSP70 and HSP90. RT-PCR method was used to detect the mRNA expression of CGI-58 and KDF1. The IPP6.0 software was used to analyze the immunohistochemistry and measure the thickness of the skin.ResultsThe general histological structure of hairy yak skin was similar to other domestic mammals. The unique features included prominent cutaneous vascular plexuses, underdeveloped sweat glands, a large number of nasolabial glands in the nasolabial plate, and hair follicle groups composed of one primary follicle and several secondary follicles. The skin, epidermis and dermis thickness did vary significantly between different body regions and different ages. The thickness of the skin, epidermis and dermis increased from newborn to adult in yaks. Yak skin thickness decreased from dorsally to ventrally on the trunk. The skin on the lateral surface was thicker than the skin on the medial surface on the limbs. HSP27, HSP70 and HSP90 showed different expression patterns during the hair cycle using RT-PCR, western blot and immunohistochemistry methods. The expression of HSP27 mRNA and protein in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of HSP70 mRNA and protein in the telogen stage was the highest, followed by the anagen stage, and the expression in the catagen stage was the lowest. The expression of HSP90 mRNA and protein in the anagen stage was the highest, followed by the telogen stage, and the expression in the catagen stage was the lowest. HSPs were mainly expressed in the outer root sheath of hair follicle during the hair cycle, also expressed in epidermis, sebaceous gland and sweat gland in the skin of Yak. The expression of CGI-58 mRNA in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of KDF1 mRNA in the telogen stage was the highest, followed by the catagen stage, and the expression in the anagen stage was the lowest.MeaningIn this study, we examined and fully described the histology of normal skin in Yak and measured the skin thickness of different ages and different regions in Yak. These data may be useful to better understand and appreciate the adaptability features of yak skin. Our investigation reports the expression patterns of HSPs in yak skin for the first time...

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Reproductive patterns of the yak. I. Reproductive phenomena of the female yak

Cited by 34 publications

References 0 publications

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Transhumant Pastoralism in Yak Production in the Lower Mustang District of Nepal

The histological characteristics, age-related thickness change of skin, and expression of the HSPs in the skin during hair cycle in yak (Bos grunniens)

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