Infertility in cows العقم عند الابقار عربي انجليزي arabe inglish pdf

 

Infertility in cows

Infertility A temporary inability to produce viable young

offspring within a stipulated time characteristic for each

species.

subfertility may imply a delayed or irregular production of the

annual live calf.

Sterility this term is used to mean an absolute inability to

reproduce.

Causes of infertility

The causes of infertility are many and can be complex. They

relate to Graafian follicle development and maturation, estrus

onset, successful coitus, ovulation, fertilization, implantation,

and the development and delivery of the fetus and its

membranes. Anything interfering with these events, such as

diseases, poor nutrition, bad herd management, hereditary

and congenital factors, hormonal disturbances or

environmental changes, make the animal infertile.`

Mainly both the congenital and acquired abnormalities that affect

the reproductive system could lead to infertility.

.

Congenital lesions of Reproductive system

Congenital lesions of ovaries congenital lesions of the ovaries

are rare, and include:

Ovarian agenesis in which one or both ovaries are absent or

lost, accompanied by an infantile genital tract and absence of

cyclical behavior.

Ovarian hypoplasia is a little more common. In this condition,

one or both ovaries are small, functionless and composed of

largely undifferentiated parenchyma. Oocytes and follicles are

virtually absent. Ovarian hypoplasia is generally a sporadic

condition.

 

Congenital lesions of the uterine tubes, uterus,and cervix

Segmental aplasia of the paramesonephric ducts

Developmental defects of the paramesonephric (Müllerian)

ducts lead to a wide range of anomalies of the vagina, cervix and

uterus. Depending upon the site of the aplasia, the cow may be

subfertile or sterile. However, the ovaries develop normally and,

consequently, affected animals show normal cyclic behavior.

Moreover, normal levels of steroid hormones are present, and

there is a significant level of secretory activity within the tubular

parts of the genital tract. Hence, when a developmental

obstruction of the tubular tract occurs, cyclical secretions

distend the lumen of the isolated portion of the tract.

paramesonephric

 

Uterine unicornis In this case, only one uterine horn has a

lumen, the other appearing as a narrow, flat band. It is more

common for the right horn to be absent than the left. Provided

the remainder of the genital apparatus is normal, individuals

may conceive to ovulations from the sound side. Animals with

this deformity are often sterile.

 

Duplication of the lumen of the cervix in this case, each

uterine horn connects with the vagina by a separate cervical

canal .Affected animals conceive normally, but may show

dystocia due to fetal limbs entering each cervical canal. A similar

complication may arise in heifers with a single cervix opening

into a double os uteri externum.

Uterus didelphys here a double cervix is present, the uterine

body is divided and there may be division of at least the cranial

part of the vagina. This condition represents a complete failure

of fusion of the two paramesonephric ducts. Such animals may

conceive, providing insemination takes place into the horn

ipsilateral to the ovulation; and a number of reports exist of

them carrying calves to term and giving birth normally.

 paramesonephric

white heifer disease This condition is considered to be due to a

sex-linked recessive gene with linkage to the gene for white

coat color. such gene induces arrest in the development

of mullarian ducts with different degrees. Originally white heifer

disease was used to describe the syndrome of straining and

illness after service in animals with retention of the hymen. In all

cases there is partial or complete persistence of the hymen. This

may be the only abnormality, but in other animals there are

abnormalities cranial to the hymen. These defects may include

the absence of the cranial vaginal cervix, uterine body or horns.

The ovaries are functional and in most cases there is a distension

of the normal organs due to the accumulation of the products of

secretion. these heifers are usually sterile.

 

Freemartinism is a heifer that born as co-twin to bull calve. It is

a distinct form of intersexuality which arises as a result of a

vascular anastomosis of the adjacent chorioallantoic sacs of

heterozygous fetuses in multiple pregnancies. although the

external genitalia of freemartin heifers appear normal, the

internal genitalia are grossly abnormal. Typically, the gonads are

either vestigial or have undergone masculinization. the gonads

resemble testes. In extreme cases, there are well-developed

epididymides, vasa deferentia and vesicular glands. Conversely,

in the least affected cases, the female genital tract may be small,

with a persistent hymen and hypoplastic ovaries.

Freemartinism 

. More typically, the vestigial gonads of freemartins are devoid of

oocytes and, hence, follicles, but have parenchyma that consists

largely of degenerating sex-cords. It is generally assumed that

92% of heifers which are born as co-twins to bulls are sterile

freemartins.

The newborn freemartin can sometimes be recognized by its

prominent clitoris with an obvious tuft of hair at the inferior

commissure of the vulva, although these signs are not always

reliable.

 Freemartins 

Freemartins can be identified on the basis of the length of the

vagina and the absence of the cervix.In the adult, the vagina is

normally 30 cm in length, compared with 8–10 cm in the

freemartin. Rectal palpation will fail to identify the cervix. In

calves of 1–4 weeks of age, the vagina is normally 13–15 cm in

length compared with 5–6 cm in a freemartin.

The most accurate method of diagnosis, although not absolute, is

the demonstration of sex chromosome chimerism in cultured

lymphocytes.Heifer calves which are born co-twins to males and

which show morphological changes in their reproductive

tracts invariably show sex chromosome chimerism in blood and

blood-forming tissues.

 Freemartins

Parovarian cysts Parovarian cysts are remnants of the

mesonephric ducts that are commonly present in the

mesosalpinx of cows. Tiny parovarian cysts, of a few millimetres

in diameter, are very common incidental findings in slaughtered

cattle. Larger cysts, of between 1 and 3 cm in diameter, may be

felt during examination of the tract per rectum when they may

be confused with ovaries. Parovarian cysts are of no

consequence to the reproductive performance of the animal,

except in the rare instances when they impinge on the uterine

tube and reduce its lumen.

 Parovarian 

Parovarian 

 

mesosalpinx 

 parovarian 

Acquired diseases or lesions of genitalia

Acquired lesions of ovaries

The most common of the acquired lesions of the ovaries, cystic

ovarian disease, is considered to be a functional disturbance of

ovarian function.

Cystic ovarian disease

Ovaries are said to be cystic when they contain one or more

fluid-filled structures larger than a mature follicle (i.e. > 2.5 cm

diameter). Cysts arise as a result of anovulation of a graafian

follicle. In cystic ovarian disease, the follicle increases in size and

persists, for at least 10 days.

Predisposing factors

Cystic ovarian disease arises as an interaction between a

hereditary predisposition, stress, milk yield, age and plane

of nutritio