Nubian Ibex (Capra ibex nubiani) [with East Caucasian Tur Capra cylindricornis]

Order: Artiodactyla

Family: Bovidae, Caprinae

1) General zoological data of species

There are perhaps eight "good" species of wild goats (Corbet, 1978), but there is much controversy attending the classification of this genus (Nowak & Paradiso, 1983). The ibex is widely distributed, including Africa, and it has a number of subspecies. They used to occur in groups numbering dozens of animals, but they are now rare and are considered to be threatened by extinction. The Nubian ibex is smaller than the Alpine form and has scimitar-shaped horns. The one distinguishing feature is the shape of their horns; their anterior surfaces are flat and broken by prominent transverse ridges. Subsequent to writing this chapter, specimens of Tur, Alpne ibex and Marhor became available. Please refer to the chapter on Alpine ibex that summarizes these findings.

2) General gestational data

In addition to the Nubian ibex, the placenta of an West Caucasian Tur (Capra caucasica), a related species, was available. Reference to its placenta will be made below. The length of gestation in the Nubian ibex is given as being between 147-180 days (Nowak & Paradiso, 1983; Puschmann, 1989). The litter size is usually one, but twins and, very rarely triplets, occur. The newborns weigh between 3.5 and 5 kg in Alpine ibex but are smaller in Nubian ibex, 1.0-1.9 kg (our average weight recorded in San Diego is 1.3 kg). The Nubian ibex is endangered. This was true of the Alpine subspecies until conservations measures were taken to conserve it.

The maternal weight is lower than the male weight of 60 kg; it was around 26 kg in the only specimen we had. The placental weight at term is unknown to us. Breeding the ibex is seasonal and occurs in the summer. The length of gestation is between 147-180 days (Nowak & Paradiso, 1983), with twins occurring occasionally. Longevity is 22 years. Successful colonies exist in the San Diego Zoo.

Typical Nubian ibex at San Diego Zoo.

3) Implantation

This cotyledonary placenta is epitheliochorial; it is implanted on the rows of caruncles of the typically bicornuate uterus. Mossman (1987) referred to contact of the spherical blastocyst and the mesometrial endometrium at about 15 days and also, that in some bovidae, perhaps the ibex, there is some interdigitation of trophoblast with intercaruncular endometrial glands.

We have had the opportunity to study the intact uterus of a female Nubian ibex that had died traumatically in early to mid-pregnancy (San Diego Zoo autopsy # 42618). There were female twins, one occupying each horn but having different directions, head down and up. The whole uterus weighed 3,300 g; after removal of fetuses and placentas it weighed 650 g. The fetuses weighed 300 g each, with a 17 cm Crown-to-Rump length. The placentas weighed 250 g each when all fluid was drained and without umbilical cords. Two corpora lutea were present in the right ovary. The cotyledons were rather flat and arranged in rows. Each horn had 45 cotyledons and corresponding endometrial caruncles. They measured from 5 x 4 cm to a few very tiny cotyledons of 0.5 cm. When they were detached they had an 0.5 cm thickness. There was no associated hemorrhage with the cotyledons. The "partition" of the bicornuate uterus was employed for placentation of both sides. Newborn twins of an additional observations weighed 1,350 g (male) and 550 g (female). A pregnant Nubian ibex died following trauma and had very young triplets in utero. The large allantoic sacs connected to each other but had no vascular connections. They were filled with a jelly-like clear fluid and contained the much smaller amnionic sac that also contained a jelly. At the free ends of the allantoic sac, the tissues were degenerated as expected. The embryos were 2 cm long, but the cotyledons had already detached at autopsy. Interestingly, the left ovary had two, the right ovary one corpus luteum, while two embryos were located in the right uterine horn. The allantoic sacs connected through the uterine connection; the cervix was filled with thick mucus. An additional placenta we saw came from a term gestation, had 35 cotyledons, weighed 132 g, had hippomanes and a 21 cm umbilical cord.

The East Caucasian Tur (Capra cylindricornis) placenta weighed 400 g, had 38 cotyledons and a 19 cm long umbilical cord. Another, more recently obtained twin placenta of tur weighed 400 g (both together), each measuring 50 x 20 cm in dimensions and one possessing 39, the other 35 cotyledons. They are shown below. The umbilical cords were 9 and 11 cm long.

Uterus of pregnant Nubian ibex.

Triplets described in text above. The embryos are labeled 1-3 and can be seen in their respective amnionic sacs. Tiny cotyledons are indicated by one arrow, the necrotic tips of the allantoic sacs are indicated by two other arrows.

One of the triplets, 2 cm in length.

4) General characteristics of placenta

This cotyledonary organ had 45 cotyledons, arranged in rows, a large allantoic sac, an epitheliochorial barrier with interdigitation of villi, and a caruncular endometrium. The fetal surface of the cotyledons was finely yellow stippled. The reason for this is unknown. There is no invasive trophoblast.

5) Details of barrier structure

As is true for most artiodactyl mammals, this placenta has a typical epitheliochorial relation between trophoblast and endometrium, as is true for most artiodactyl mammals.

Opened uterus of pregnant Nubian ibex with immature twin fetuses, and placenta still attached.

Uterus of same ibex with placenta and fetuses removed. Note the rows of maternal caruncles.

Twin placenta of Caucasian tur.

Pregnant uterus with twin fetuses from posterior. Note the large pink ovaries.

The same uterus opened, with small embryos in each horn.

6) Umbilical cord

The cord has a midmesometrial location (Mossman, 1987), possesses four blood vessels and a large allantoic duct. It was not spiraled and measured 9 x 1.5 cm at this gestational age. There were no surface callosities. No hippomanes were present in this specimen and there was no vitelline duct.

7) Uteroplacental circulation

No information is available.

8) Extraplacental membranes

The amnio-allantoic partition was very thin, with the delicate allantoic blood vessels easily demonstrable.

9) Trophoblast external to barrier

There were neither extravillous trophoblast, giant cells nor vascular trophoblastic invasion.

10) Endometrium

There was no endometrial decidualization.

Triplet pregnancy after detachment of the immature cotyledons, to show some of the small caruncles in one uterine horn at white arrows.

11) Various features

No subplacenta is present.

12) Endocrinology

The estrus is short, 1-2 days (Puschmann, 1989) and seasonal; reproductive maturity occurs at 2 1/2 years. The breeding interval is 1-2 years. The reproductive biology of the close relative, the Alpine Steinbock, has been detailed by Stüwe & Grodinsky (1987). They found them to be seasonally polyestrous with the estrous cycle 20 days long, and a gestational length of 167 days.

While no work has been reported on ibex, there is much information of the placental function in sheep and goat. This is adequately summarized by Porter et al. (1982). It is generally accepted that the sheep placenta produces progesterone in later gestation and becomes independent of the corpus luteum. This does not appear to be the case in goat placentas. For that reason, it is conjectured that sheep x goat hybrid pregnancies are compromised. The generation of gonadotropins from the placenta has not been reported (Courrier, 1945). The contribution by Porter et al. (1982) also discussed relaxin production and onset of labor.

13) Genetics

This species has 60 chromosomes, all acrocentrics, similar to the domestic goat (Hsu & Benirschke, 1969).

Hybridization with Markhor (Capra falconeri) and domestic goat (Capra hircus) has been reported (Gray, 1972). The latter are said to be fertile and they are hornless if a hornless domestic goat was used for the hybridization. When introduced into the wild, they failed to prosper, perhaps because of an unfavorable weather condition at the time of their births (Stüwe & Grodinsky, 1987).

No additional genetic information is available.

Karyotypes of male and female ibex. (From Hsu & Benirschke, 1969).

14) Immunology

No MHC molecules, NK cells, or other relevant cell populations have been described for this species.

15) Pathological features

Griner (1983) reported on the mortality of 14 ibex in the collection of the San Diego Zoo; most were due to trauma. Neonatal mortality was very high and one case of hydronephrosis was described.

16) Physiological data

No information is available.

17) Other resources

Cell strains of Nubian ibex are available from CRES at the Zoological Society of San Diego by contacting Dr. Oliver Ryder at oryder@ucsd.edu.