Breeding Soundness Examination of Bulls

Bulls need a thorough breeding soundness examination before drafting them to regular semen collection and introduction into the A.I programme. About 20% of are reported to have a low fertility and their use in A.I programme is an economical loss to the farmers. The breeding soundness examination gives the status of the bull on the date of examination. It cannot reflect its past soundness or its ability for the conception. It can give an indication of its future fertility. Many factors should be taken into consideration before declaring the bull as fit for breeding. However the objective of breeding soundness examination is to eliminate infertile or sub fertile bulls from the breeding programme.

Procedure for Breeding Soundness Examination (B.S.E.)
Generally the Zebu bulls can be examined at the age of 18-24 months whereas buffalo bulls at 24-30 months as they mature lately. The following aspects should be taken to consideration and studied in detail. Finally depending on the observation the bull can be declared as satisfactory, questionable or unsatisfactory for breeding.

  1. General information (History)
  2. General health and physical examination
  3. Examination of external genital organs
  4. Examination of internal genital organs
  5. Libido and sex drive
  6. Semen evaluation

All the above factors should be examined in detail and recorded in a sheet prescribed for the breeding soundness examination.

General information (History):

  • Bull no
  • Name of the bull
  • Breed
  • Date of birth/Age
  • Birth weight
  • Present weight
  • Earlier clinical sheets of the bull and treatments, vaccinations given to the bull
  • Date of first collection
  • Number of collections made during the last 6 months
  • Conception rates if any

General health and physical examination
It is essential to examine the bull for its general health and physical condition since the mating ability of the bull is dependent on them. The following aspects should be studied. (Refer table)

Eyes: Eyes should be bright, alert. The bull should have a good vision and the mucus membranes should be pink. Blindness, opacity of the cornea, wall eyes, carcinoma of the eyes is all disqualifications. If present the bull is nor fit for breeding and therefore should not be selected.

Nostrils: Should be normal, bright and moist.

Mouth: All the teeth should be present and healthy. There should not be any over grown molars or teeth making the bull difficult for mastication. The dentition should be examined.

Ears: The ears should be normal without any discharges or infections in the ears.

Skin: The skin should be glossy and free from ectoparasites. The external lymph glands should be normal and not palpable.

Gait: The bull should walk normally since the mounting ability depends on it. Defects in the feet and legs disqualify the bull for breeding. The animal is made to walk and the gait should be examined while the observer standing in front and back of the bull. Fractures, dislocations, luxation of patella make the bull disqualified for selection. The bull is also examined for the condition of the hooves. Overgrown hooves, weak pasterns are not suitable for selection. Sickle hock conformation, post leg bulls (lack of proper angulations of hocks). Cramped legs, bowed legs, toed out legs are disqualification for selection. Defects in the legs affect the mounting ability of the bull. Further the hooves also should be examined for the presence of inter digital growths (Fibromas), foot abscesses, foot rot etc.

Examination of external genital organs:
The following external genital organs are to be examined.

  • Scrotum
  • Testis
  • Epididymis
  • Penis
  • Prepuce

Scrotum: The scrotum is situated in the inguinal region medial to the thighs hanging perpendicularly. The bull is controlled properly in a trevis and left without disturbing him for some time in the sun light. This facilitates the scrotum to get relaxed and hangs freely in the thighs. This helps in easy observation and handling for examination. The scrotum should be handled gently without unnecessarily causing any pain to the bull. If the bull feels any discomfort it jumps making the examination difficult. The following aspects are to be examined.

Position: Abnormal position of the scrotum should be examined. Slight rotation of testis is normal to certain bulls. Complete rotation of scrotum is not normal as the semen quality gets affected. Such bulls should not be selected.

Physical examination: Examine for the presence of injuries, insect bites, scars, and any other developmental abnormalities.

Shape of the scrotum: The normal shape of the scrotum in zebu bulls is oval but variations do occur in many bulls. The shape of the scrotum has no bearing on the semen quality. In Murrah buffaloes bulls the shape of the scrotum varies from oval, small, round and oblong. In some bulls the scrotum sometimes will be bifid completely separating both the testis which can also be taken as normal since it has no bearing on the quality of semen. Abnormal conditions like hernia, swelling, abscesses of the scrotum, adhesions and tumors should be examined. All these conditions affect the quality of the semen and semen producing ability of the bull. Bulls having pathological conditions in the scrotum should not be selected.

Scrotal circumference: After complete relaxation of the scrotum the circumference should be taken. It is proved that the scrotal circumference has a direct bearing on the production ability of the bull. It can be measured with a measuring tape.

Procedure for measuring scrotal circumference: The circumference of the scrotum should be measured at the widest point. Hold the scrotum at the neck without compressing and place the tape at the widest part making it as a loop around the scrotum. After keeping the tape in correct position measure the circumference and record. ( See figure)

Testis: Both the testis should be palpated and evaluated during the examination. Restrain the bull properly in the trevis approach from behind and gently hold the scrotum in both the hands and examine for its size, shape, form, and consistency. Both the testis should move freely in the scrotum when pushed and the bull should not evince any pain or signs of discomfort. Both the testis should be tight and when slightly pressed springiness should be observed. Hardness is an abnormality and possible fibrosis. Both the testis should be symmetrical and present. The following common pathological conditions should be examined.

  • Hypoplasia of the testis
  • Asymmetry
  • In complete descent
  • Cryptorchidism
  • Soft testis

The length of the testis should be measured with a scale or vernier calipers and noted in the BSE sheet.

Epididymis: The epididymis consists of head, body and tail. It should be examined for its size, form, and consistency. In the bull the alterations in the epididymis are generally rare. The tail of the epididymis located at the bottom of the testis seen as small projection. The head can be examined on the upper part normally difficult to palpate. Genetic abnormalities like Hypoplasia or aplasia (Complete absence) may occur in some bulls. Inflammation of the epididymis sometimes will be present associated with pathological conditions like vesiculitis, architis etc. If inflammation is present the parts are swollen and painful.

Penis: The penis can best be examined when the bull is mounting. The penis can also be pulled by giving peudental nerve block relaxing the penis. Electro ejaculator can also be used but it is very painful and should be avoided. The following conditions should be examined

  • Injuries
  • Adhesions
  • Lacerations
  • Papillomatous growths
  • Deviations of the penis

Size of the penis (Examine while the bull is mounting)

Prepuce: Examine the sheath for the following conditions.

Shape: Pendulous or tucked up. Pendulous sheath is disqualification since dirt, dung and bacteria accumulate in the folds and result in contamination of semen. Hence selecting such bulls should be avoided as far as possible.

Adhesions: Examine the prepuce for presence of any adhesions by palpation.

Phimosis: Bulls unable to extend the penis.

Para phimosis: Bulls cannot retract the penis into the prepuce.

Any other pathological conditions

Pendulous sheath and prolapse of prepuce with loose folds of mucous membrane are undesirable characters. But in some Zebu bulls like Sindhi, Sahiwal and Tharparkar the prepuce is often loose and mucous folds prolapse which is considered normal.

Examination of internal genital organs
Examine the following internal genital organs for any pathological conditions and for their presence. The internal genital organs should be examined by means of rectal palpation. Restrain the bull properly. Lubricate the hand with liquid paraffin and pass the hand into the rectum .Gentle handling is important. Identify the pelvic floor over which the pelvic urethra is located. It is like a cylinder of 3-4cm in diameter.

Prostate gland: It is situated on the anterio dorsal part of the pelvic urethra. After identifying the prostate gland pass the hand forward and side ward to locate the seminal vesicles and ampullae.

Seminal vesicles: The seminal vesicles are paired organs located on either side of the ampullae as two lobed structures freely moving. Examine them for any inflammatory changes, size and consistency. Normally they are soft to touch in young bulls becomes firmer as the age advances. In zebu bulls they are 6-8 cm long 2-3 wide and 1-2 cm thick. In buffalo bulls they are smaller and less lobulated. In healthy bulls they are freely movable. In pathological conditions they cannot be moved freely and the animal evinces pain while handling. Seminal vesiculitis is common in which the semen quality is also affected and more number of W.B.C. are seen in the ejaculate. In chronic seminal vesiculitis they are harder and indurated associated with poor semen picture. Sometimes one or both the lobes will be absent (Aplasia) which is genetic in nature.

Ampullae: Ampullae are paired finger like structures lying between the seminal vesicles on the pelvic urethra. Inflammation of the ampullae sometimes seen but usually associated with seminal vesiculitis.

Sexual behavior of bulls:
Studying the sexual behavior of is very important in breeding soundness examination of bulls since the usefulness of the bull mainly depends on its mounting ability. Examine the bull for the following aspects.

Libido: ‘Libido’ is the bull’s interest in mounting the female or the dummy used for the semen collection. The bull should evince interest and show eagerness to mount. The libido can be examined while the bull is still young as active bulls show interest to mount on other bulls while they are in the open paddocks.

The following parameters should be taken into consideration to assess the libido of the bull.

  • Type of dummy required whether a male animal or a female
  • Interest of the bull to approach the dummy Active/ Slow/ not showing interest

Reaction time: Time required for the bull to ejaculate measured from the time it is brought to the dummy till it ejaculates.

  • Sniffing
  • Lumbar movements
  • Penile movements
  • Thrust; Good/ Poor

Detailed evaluation of semen (semen analysis)
When all the preliminary examination is over the semen of the bull should be evaluated. It gives a complete picture of the sex organs and earlier observations can be correlated. The various parameters to be observed are as follows.

Physical parameters:

  • Volume
  • Colour
  • PH
  • Visual density
  • Microscopical parameters
  • Mass activity
  • Initial motility
  • Sperm concentration
  • Morphological abnormalities (Spermiogram)

Physical parameters

Volume: Young bulls ejaculate less volume than the older bulls. Buffalo bulls give 2-3 ml of semen whereas Zebu bulls give 3-5 ml .Bulls constantly giving less volume of semen along with low concentration are not economical to maintain. Such bulls should be culled. While semen collecting rough handling, frequent change of the dummy, improper temperature of the AV (High or low temp) and change of site of collection should be avoided. All of these factors influence the semen quality.

Colour: Normal colour of semen in Zebu bulls is creamy whereas buffalo bull semen is white. Sometimes the semen of Zebu bulls will be yellowish which is normal. The following are the abnormal colours of semen

Brown colour of semen: Indicates presence of architis

Frank blood in semen: Injury to the penis or urethral tract.

Green colour: Presence of pus in the semen

PH of semen: The PH of semen in clinically normal bulls is slightly acidic about 6.7 and 6.9for buffalo semen. On storage the PH further declines towards more acidic side due to formation of lactic acid. Highly motile semen is acidic whereas poor quality semen is more alkaline.

Microscopical parameters:
Mass activity: Examination of mass activity of semen should be done on a microscopic stage fitted with a biotherm maintained at 370C. A small drop of semen is put on a clean slide and examined in low power (10x). A good sample of semen will have a lot of waves (Swirls and eddies) with quick movement which is graded as 3+. Poor samples without any waves are graded as 0 or 1 or 1+. The mass activity is correlated with motility and concentration. Therefore individual motility also should be checked for grading the semen quality.

Initial motility/Individual motility: Take a small drop of neat semen on a clean glass slide and place a cover lip of 22×22 mm size and slightly press for even spreading of the drop. Examine the motility on a stage with a biotherm using a phase contrast microscope under 40 x magnifications. Observe the % of progressively motile spermatozoa. If the semen sample is highly concentrated dilute the semen with 2.9% sod citrate solution and observe the motility. A good sample should possess more than 80% progressively motile sperms. Motility is a good parameter to judge the bull for its fertilizing capacity.

Concentration of spermatozoa: Semen concentration in bull semen varies from 800-1500 millions/ml of semen. Young bulls ejaculate semen with higher concentration. As the age advances the semen concentration will decline. Bulls donating constantly semen with low concentration below 600 millions/ml are not economical for breeding purpose. Semen concentration in zebu bulls and crossbred bulls is higher than that of buffalo bull.

Semen morphology (Morphological abnormalities of semen): The Spermiogram is a reflection of the health of the testis, epididymis and to some extent accessory sex organs. Evaluation of semen gives an idea about the quality of semen and indirectly the fertilizing ability of the bull. Before interpreting the results Spermiogram the other conditions like health of the bull, nutrition, environment, management practices, vaccination details, and the semen picture of the for the last six months should be taken into consideration. There is lack of sufficient information about the role of the morphological abnormalities in relation to fertility. Therefore the inference of the Spermiogram should be carefully be given on individual merits.

The morphological abnormalities are classified as major and minor (Bloom 1971). All the defects of the head, midpiece and the tail are to be studied. In addition the presence of epithelial cells, immature cells, W.B.C, and R.B.C also should be examined and the results to be correlated with the earlier observations. More than 20% of total abnormalities is regarded as problematic and suggestive of testicular degeneration or disturbed spermatogenesis. While evaluating the morphological abnormalities of spermatozoa at least 200 sperms should be counted for more accuracy. Along with the morphology live and dead % of sperms also should be evaluated. The semen can be stained with Eosin and Nigrosin stain to study both the morphology and live and dead %. The following are the morphological defects generally observed.

Major sperm defects:

  • Immature forms
  • Double forms
  • Acrosome defects (Swollen, detached, fractured, and knobbed sperms)
  • Loose heads
  • Diadem defect
  • Pear shaped heads
  • Narrow at the base
  • Abnormal contour
  • Small abnormal heads
  • Cork screw defect
  • Bent midpiece
  • Swollen mid piece
  • Degenerated mid piece
  • Strongly coiled and folded tails

Minor sperm defects :

  • Narrow heads
  • Small normal heads
  • Abaxial implantation
  • Distal protoplasmic droplet
  • Simple bent tail
  • Terminally coiled tail

Morphological defects of possible genetic origin:
Loose sperm head defect: Commonly seen in guernsey breed. Normal spermatozoa are virtually absent or never exceed 5% and the ejaculate contains only heads and free tails. The sexual behavior and the clinical examination is normal and do not show any pathological abnormality.

Knobbed sperm defect: The acrosome will have a protrusion to outside or inside resembling as a vacuole. The concentration and the motility are normal. The post thaw motility after freezing is poor. The fertility rates are also poor.

Pouch formation of nuclear envelope: (Diadem defect): The abnormality is seen as white glistening spots in the nucleus of the sperm giving the appearance as though a necklace is tied around the neck. This is associated with disturbance in spermatogenesis.
Cork screw defect: A mid piece defect of the sperm due to irregular distribution of the mitochondrial sheath. This defect is seen in aged bulls associated with testicular degeneration.

Pseudo droplet defect: Thickening of the mid piece at some place giving a false impression of a proximal droplet of cytoplasm. The initial motility of the sperm is poor.

Dag defect: The tail is tightly folded and sometimes seen as though a mass attached to the head. The motility is poor It is also reported in Murrah buffalo bulls.

Acrosomal evaluation: The presence of an intact acrosome is essential for fertility. Acrosomes are subjected to damage during freezing and thawing. Counting the number of sperms having intact acrosomes before and after freezing will help in assessment of the fertilizing ability of the bull. Semen smears stained with Giemsa can be evaluated for the integrity of the acrosomes. High % of intact acrosomes indicates good quality of semen. A minimum of 65% intact healthy acrosomes are essential for optimum fertility. Along with intact acrosomes damaged acrosomes should be counted. A well defined apical ridge of the Acrosomal cap can be taken as an intact acrosome.

After complete evaluation of the bull for B.S.E the bull has to be classified as fit for breeding, questionable, or unfit for breeding taking all the observations in the B.S.E. Questionable should be observed or treated and if no improvement is seen should be removed from the breeding programme.

Table 3

Average body weight, scrotal circumference, and testis length in relation to age in Murrah, Ongole, Jersey and Jersey x ongole cross bred bulls stationed in frozen semen bull stations in Andhra Pradesh, India

 

Age (Years)

Murrah bulls

(18)

Ongole

(18)

Jersey

(28)

Jersey X ongole

(22)

BW

(Kg)

SC

(Cm)

TL

(Cm)

BW

(Kg)

SC

(Cm)

TL

(Cm

BW

(Kg)

SC

(Cm)

TL

(Cm)

BW

(Kg)

SC

(Cm)

TL

(Cm)

1.1 to 1.5 230 19.0 6.0 - - - - - - - - -
1.5to 2.0 285 23.0 6.0 - - - - - - - - -
2.1 to 2.5 340 25.0 6.5 350 29.0 9.5 300 32.0 10.0 300 30.0 10.0
2.6to 3.5 450 27.0 7.0 480 32.0 10.0 420 35.0 13.0 425 32.0 10.0
3.6to 4.5 550 30.0 7.5 540 33.0 12.0 500 37.0 14.0 560 33.0 11.5
4.6to 5.5 600 30.5 8.0 630 33.5 14.0 560 38.0 14.0 565 34.5 11.5
5.6to6.5 630 32.0 8.4 670 37.0 14.0 600 40.0 14.0 570 34.5 11.5
6.6to7.5 600 32.0 8.8 700 36.0 12.5 570 38.0 12.0 570 34.0 11.0

Courtesy:  Dr. A.V.N. Rao, Age and Breed related changes in body weight and testis size in bulls. IVJ.69, 1902 P415-418 BW-Body weight, SC-Scrotal circumference, TL: Testis length

 

Table 4

Birth weights of bull calves of different breeds

Breed

Weight (Kg)

Range (Kg)

Jersey

23

23-25

Jersey x ongole

30

28-30

Ongole

28

26-28

Murrah

29

28-30

Holstein Frisian

40

38-40

Tharparkar

22

22-24

Sindhi

24

23-25

Sahiwal

22

22-24

21

21-23

Courtesy Dr A.V.N. Rao

Table no 5

Semen production traits in relation to age in Murrah Buffalo Bulls

Stationed at frozen Semen Bull Stations in A.P. India

Age(Years) Semen volume

ml

Concentration

X 106

Sperm per ejaculate x106

<3.5

2.3

1286

2990

3.6 to 4.5

2.4

1418

3400

4.6 to 5.5

2.7

1326

3515

5.6 to 6.5

3.0

1441

4475

6.6 to 7.5

2.8

1301

3660

7.6 to 8.5

2.8

1224

3410

8.6 to 9.5

2.5

1184

2995

9.6 to 10.5

3.1

1201

3660

>10

3.6

1142

4012

Courtesy: Dr.A.V.N. Rao