Breeding Soundness Evaluation (BSE) of Bulls

Transcription

1 Breeding Soundness Evaluation (BSE) of Bulls

2 Beef Bull Evaluation Reproductive merit economically > important than growth and carcass quality Evaluate Before purchase Before each breeding season If infertility is suspected

3 Beef Bull Fertility ~30% of beef bulls are not satisfactory potential breeders In multi-sire systems, an infertile dominant bull can breed most of the females

4 Facilities Also require temperatures >10 o C, and shelter

5 History Perceived fertility Libido and mating ability Previous or present disease conditions

6 Initial Examination Record permanent identification General condition

7 Check the Eyes

8 Check Locomotion and the Legs Defects in conformation Joint and other swellings

9 Examine the Feet Interdigital hyperplasia Claw defects

10 Check the Underline

11 Normal Anatomy

12 Scrotal Shape Straightsided Pointed Normal, pendulous Undesirable

13 Examination of the Scrotal Contents Approach Anatomy

14 Check the Scrotum for Lesions Example - frostbite

15 Examination of the Scrotal Contents Checking mobility of the testicles Palpating the testicles Examining the heads of the epididymides Spermatic granuloma

16 Examination of the Scrotal Contents Palpating the body of the epididymis Palpating the tail of the epididymis Epididymitis WBCs in a semen smear stained with Diff-Quik

17 Scrotal Circumference Measuring Tapes

18 Measuring Scrotal Circumference Correct method Incorrect method

19 Minimum Minimum Standards for Scrotal Standards for Scrotal Circumference Circumference Texas Texas Longhorn Longhorn Limousin Limousin, Salers Salers, Blonde Blonde D Aquitane Aquitane, Galloway Galloway Hereford, Hereford, Shorthorn, Shorthorn, Tarantais Tarantais Charolais Charolais, Angus, Angus, Maine Maine Anjou, Anjou, Red Poll, Red Poll, South South Devon, Devon, Holstein Holstein Simmental, Simmental, Gelbvieh Gelbvieh, Pinzgauer Pinzgauer, Brown Swiss Brown Swiss Age Age (mos mos)

20 Scrotal Circumference Moderately to highly heritable Positively correlated to paired testes weight and sperm production Positively correlated to early maturity and semen quality Positively correlated to early maturity and fertility in related heifers

21 Effects of Nutrition on Scrotal Dietary restriction will delay puberty High energy diets fed to bulls >12- months-old old can result in excess scrotal fat Circumference

22 Small Scrotal Circumference Bulls with small SC for their age usually remain that way for the rest of their lives.

23 Transrectal Examination of the Internal Genital Organs

24 Seminal Vesiculitis

25 Semen Collection Electoejaculators and probes

26 Collection Devices

27 Collection Technique

28 Collection Technique Increasing, rhythmic stimulations Stimulations last seconds with rest period of ~1/2 second in between

29 Collection Technique

30 Alternative Technique

31 If the Penis Doesn t t Protrude

32 Examine the Penis for Lesions or Examples: Abnormalities Persistent frenulum Hair ring Warts

33 The Occasional Bull Can t t be Collected by Electroejaculation

34 Collection Using an Artificial Vagina Can be time-consuming and dangerous

35 Semen Evaluation Equipment to keep the semen warm and a good-quality microscope is required.

36 Semen Evaluation Will be Presented in the Laboratory Sperm cell motility Gross motility (wave motion) % progressive motility, especially on less concentrated samples In some cases, poor motility may improve with subsequent collections Sperm cell morphology Volume and density (approx. concentration) are also recorded

37 Records Forms are available

38 Classification Satisfactory potential breeder Questionable potential breeder Unsatisfactory potential breeder Decision deferred E.g., a bull <16-months months-old old that is OK in all aspects except semen quality May be the result of immaturity

39 To be a satisfactory potential breeder a bull must: Be physically sound and healthy Have a normal reproductive tract Have a scrotal circumference that meets or exceeds minimum standards Have satisfactory semen quality Have satisfactory libido and mating ability Often assessed by the owner

40 Breeding Soundness Classification Not meant to guarantee fertility Select bulls that are satisfactory potential breeders Eliminate bulls that are not satisfactory Can re-evaluate evaluate at a later date

41 Serving Capacity Tests libido and mating ability Not routinely determined Owner observation is important E.g., spiral defect of the penis only diagnosed at mounting

42 Effect of Libido on Conception Rates 50 heifers/bull for 20 days Libido Score High & Medium Conception rate 54% Low 16%

43 Serving Capacity Test

44 Questions?

45 Breeding Soundness Evaluation of Rams and Bucks

46 Breeding Soundness Evaluation of Rams and Bucks Similar to BSE of bulls except: Unable to examine the internal reproductive organs Ram s s teeth should be checked in addition to body condition, conformation, feet, legs and eyes There are seasonal effects on testicular size, sperm production and libido In endemic areas, breeding rams should be negative for Brucella ovis

47 Examination of the Scrotum and its Contents Similar to bulls

48 Semen Collection Training for collection with an artificial vagina can be time-consuming Usually collected with an electroejaculator Probe for use on small ruminants

49 Electroejaculation Rams can be collected restrained in a head gate or on their side Bucks are collected restrained in a head gate, usually with mg xylazine sedative IV Stimulations last seconds with rest period of seconds in between

50 Semen Collection The semen is often collected into a warm Whirl-pak bag The penis can be grasped with a sponge for examination and to prevent loss of ejaculate (0.5-3 ml)

51 Semen Evaluation Will be presented in the Laboratory Sperm concentration should be high Motility Usually assessed by wave motion Sperm cell morphology

52 Classification Same as for bulls Can re-evaluate evaluate at a later date Questions?