Why Do Sheep Have Large Testicles

Why Do Sheep Have Large Testicles

Testicle size is a good indication of the sperm-producing ability of individual rams. If Not Diseased Represents sperm storage capacity. It will be Largest During the Months of August – October. Rams can Be Given a (BSE) Breeding Soundness Examine by a Veterinarian to determine virality.


Puberty typically occurs in the ram at 6 months. It is defined as the point at which the ram develops an interest in sexual activity and produces spermatozoa in sufficient numbers to achieve pregnancy in ewes. The exact age at puberty depends somewhat on breed and time of birth. Rams born early in the spring are older at puberty than late-born lambs.

Moreover, rams that are periodically exposed to cycling ewes tend to reach puberty earlier. Rams are seasonal breeders: Sperm quality, daily sperm output, and sexual activity are modulated by the increased periods of darkness that are typical of fall.

This seasonality in the ram also is manifested by an increase in the testicular circumference (by approximately 1 to 2 cm). The increase in melatonin, which is secreted from the pineal gland during the dark hours as day length shortens, is responsible for many of the physiologic mechanisms associated with the transition of the ram from the non-breeding to the breeding season. 

New Zealand Sheep Large Testicles

Manipulation of light-dark intervals and the use of melatonin can alter the breeding season of rams.

A change in the sexual attitude of the ram toward the ewe as day length decreases defines the onset of the breeding season. He becomes more sexually interested in the female, and courtship behavior occurs more frequently.

Rams display a typical flehmen response to females in estrus after sniffing the vulva region and urine from the estrus female. The ram often strikes out at the female with one front leg before mounting her.

The physiologic changes in testicular size, mating behavior, and semen quality are caused by the activation of the hypothalamus and a decrease in the effectiveness of testosterone on the negative inhibition of gonadotropin-releasing hormone (GnRH). Significant differences are seen between the breeding and the nonbreeding season with respect to the pattern of GnRH and luteinizing hormone (LH) pulses and the response of the pituitary gland to GnRH.

Structure of Testes in Ram

The testicles are suspended away from the body within the pendulous scrotum. The scrotum is composed of undulating epidermis that may or may not is covered by wool or hair, depending on the breed and husbandry practices. A rich plexus of blood vessels, lymphatics, and sweat glands lie beneath the skin.

The dartos, a smooth muscle layer, is connected to the vaginal tunics of the testicle by the scrotal fascia. The scrotal fascia is the connective tissue that typically is broken down in separation of the skin from the testicle during routine castration. The vaginal tunics are outcroppings of the peritoneum and form a protective covering over the testicles.

The space between the two layers of the vaginal tunic (parietal and visceral) as it reflects around the testicle normally contains a small amount of peritoneal fluid. The scrotal septum, composed primarily of the dartos muscle, divides the scrotum into two halves.

Primer Checking a Rams Testicles

The testicle itself is surrounded by a thick layer of fibrous connective tissue known as the tunica albuginea. The parenchyma of the testicle is composed of seminiferous tubules that contain the germ cells and their supporting cells (Sertoli cells).

The seminiferous tubules drain into the rete testes, which in turn is drained by 10 to 12 efferent ducts. These ducts drain into the head of the epididymis, which is located on the dorsal craniolateral aspect of the testicle. The body of the epididymis curves around the lateral portion of the testes and ends caudomedially as the tail. The tubular structure is reflected dorsally and becomes the vas deferens. Rams and bucks have a full complement of accessory sex glands.

The small bulbourethral glands are located caudally in the pelvic cavity on either side of the pelvic urethra and can be palpated rectally. These animals also have lobulated vesicular glands, disseminate prostates, and a widening of the vas deferens known as the ampulla. Spermatogenesis requires approximately 49 to 60 days from the start of germ cell division until the spermatozoa are released from the seminiferous tubules. Another 10 days to 2 weeks are required for the sperm to pass from the seminiferous tubules through the epididymis.

Breeding Soundness Examination in the Ram

A breeding soundness examination (BSE) should be performed on all rams before the beginning of the breeding season. With the ram being expected to breed as many as 100 ewes during a season, his individual worth far outweighs the cost of a BSE. A proper BSE consists of a thorough physical examination with special attention to the scrotum and testicles, as well as an evaluation of the semen quality.

Most BSEs do not routinely include an evaluation of the ram’s libido or his physical ability to make intromission. The veterinarian should communicate clearly with the client regarding the limitations of the BSE performed and the need for some sort of libido testing.

Such testing often can be accomplished by directly observing the animal in the first part of the breeding season. Large sheep producers may be encouraged to keep an extra 10% of rams deemed satisfactory for reproductive purposes by veterinary examination, to ensure adequate “ram power.”

Breeding Soundness Examine

Examination of Reproductive Tract

The scrotum should be palpated to ensure that both testicles are present, approximately equal in size, and of firm consistency; any localized swellings or areas of induration should be noted. The head and tail of the epididymis are palpated to detect swelling, pain, or signs of inflammation. Epididymitis is a relatively common problem in rams.

Any ram exhibiting signs of epididymitis should be considered to be infected with Brucella Ovis until proved otherwise. The spermatic cord should be examined specifically for deformities in the vascular plexus and vas deferens. The penis usually can be extended by pressing down around the external preputial orifice and grasping the protruding penis with a gauze pad (Figure 8-1).

Occasionally the sigmoid flexure may need to be straightened to assist in extending the penis. The penis is then carefully inspected for evidence of active lesions or old scars. The penis can be held in extension by wrapping a strip of gauze around the junction between the free portion of the penis and the prepuce. This method also is helpful in collecting semen by electroejaculation. The penis generally is easier to extend when the animal is being held up on the rump than when it is in lateral recumbency.

Scrotal Circumference

To determine the SC, the clinician should pull both of the ram’s testicles ventrally into the scrotum and measure it at its largest circumference, using a tape measure marked in centimeters. Care must be taken with breeds that have heavy scrotal wool, because wool may falsely enlarge the measured circumference.

Taking the average of several measurements can increase the accuracy of the SC value obtained. The tape should be snug on the scrotum, while barely indenting the skin so that the tape does not slide out of position (Figure 8-2). SC in the ram is highly heritable and appears to be related to sperm output and age at puberty.

For the selection of ram lambs, the testicular diameter at 170 days provides a long-range prediction of post-pubertal testicular size and sperm output. SC is a major criterion for selecting replacement rams. Minimum accepted SC’s of 30 cm for ram lambs weighing more than 150 lb., 33 cm for 12- to 18-month-old rams, and 36 cm for rams weighing more than 250 lb. have been suggested. 

How to Check Ram for Breeding Condition

Strictly on the basis of age, rams at 8 to 14 months should have SC’s of 28 to 36 cm to be classified as satisfactory and more than 36 cm to be classified as exceptional. Rams older than 14 months should have SC’s of 32 to 40 cm to be classified as satisfactory and more than 40 cm to be classified as exceptional.

Scrotal size usually is greatest from August to October. Smaller testicular measurements (0.5 to 1.5 cm less) are to be expected when rams are tested outside of the normal breeding season (February to April) or during periods of extreme sexual activity.

Sperm Production in Rams

Sperm production in rams takes 49 days. You must ensure rams are well looked after during the 7-8-week period leading up to joining, to avoid factors that could adversely affect the sperm and lead to temporary infertility.

Checking Ram Sperm Reserves

The epididymis is a part of the ram’s testicles that absorbs testicular fluid and enables large quantities of sperm to be stored in the smallest possible space. It’s located in the back-rear section of each testicle.

Checking the tail of the epididymis can give you a useful guide to the level of sperm reserves in rams. A large, firm (but not hard and diseased) epididymis is an indication of good reserves, while a small, soft tail indicates the opposite.

Testicle Size in Rams

Testicle size is a good indication of the sperm-producing ability of individual rams. Sperm are produced by testicular tissue at a reasonably constant rate of about 20 million sperm per gram of testis per day. You can check the size of a ram’s testicles for the reasonably good judgment of the ram’s stores of sperm.

Large testicles can also be an indicator of higher levels of testosterone, which is an important factor in the ram’s sexual interest. It’s important to avoid selecting rams with small testicles, as this is equally likely to be a sign of low sperm availability in the animal.

Temperature and Sperm Production in Rams

For normal sperm production to occur, the testes need to be kept cool. A ram’s natural cooling mechanism includes large sweat glands in the skin of the scrotum and a system of muscles that raise or lower the testes into the body for the purpose of temperature regulation. Blood flow to the testes also helps to regulate temperature through a heat exchange mechanism.

Hot weather, such as long periods of temperatures over 32 degrees Celsius, or short spells of very high temperatures (38 degrees Celsius or higher), affects the production of viable sperm. Rams that are heat stressed before joining could still successfully serve ewes up until the sperm stored before the heating is used (about 2-3 weeks), but it will then take 7 weeks to produce new viable sperm.


Sheep Farming for Wool Profitability Table

SheepLambs / 3 Per YrSpace Required 20 Sq Feet - EachGrazing Acres .3 / SheepFeed Required / Yr $10015 Lbs Wool / YearAverage Price $ 10 / LB WoolTotal Revenue Possible
1360 sq ft.9 acres$ 30045 lbs$ 450$ 150
26120 sq ft1.80 acres$ 60090 lbs$ 900$ 300
515300 sq ft4.5 acres$ 1,500225 lbs$ 2,250$ 750
1030600 sq ft9 acres$ 3,000450 lbs$ 4,500$ 1,500
20601200 sq ft18 acres$ 6,000900 lbs$ 9,000$ 3,000
30902,700 sq ft27 acres$ 9,0001,350 lbs$ 13,500$ 4,500
401204800 sq ft36 acres$ 12,0001,800 lbs$ 18,000$ 6,000
501503,000 sq ft45 acres$ 15,0002,250 lbs$ 22,500$ 7,500
1003006,000 sq ft90 acres$ 30,0004,500 lbs$ 45,000$ 15,000
20060012,000 sq ft180 acres$ 60,0009,000 lbs$ 90,000$ 30,000
Sheep can give Birth 6+ lambs every Two Years
Sheep can Produce 2 - 30 lbs of wool per year depending on Breed
Raw washed Wool Runs $ 6 - $ 14 using average $ 10
Feed 5 Months Buying Hay $ 100 rest Grazing
Please Check my Numbers

Sheep Farming for Milk Profitability Table

SheepLambs / 3 Per YrSpace Required 20 Sq Feet - EachGrazing Acres .3 / SheepFeed Required / Yr $100Wool $ 15 lb / YearAverage Price $ 10 / LB Wool90 Gallon/ Yr each ewePrice $ 30 per GallonTotal Wool Revenue PossibleTotal Revenue Milk and Wool
1360 sq ft.9 acres$ 30045 lbs$ 4502708100$ 1508,250
26120 sq ft1.80 acres$ 60090 lbs$ 90054016,200$ 30016,500
515300 sq ft4.5 acres$ 1,500225 lbs$ 2,250135040,500$ 75041,250
1030600 sq ft9 acres$ 3,000450 lbs$ 4,500270081,000$ 1,50082,500
20601200 sq ft18 acres$ 6,000900 lbs$ 9,0005400162,000$ 3,000165,000
30902,700 sq ft27 acres$ 9,0001,350 lbs$ 13,5008100243,000$ 4,500247,500
401204800 sq ft36 acres$ 12,0001,800 lbs$ 18,00010,800324,000$ 6,000330,000
501503,000 sq ft45 acres$ 15,0002,250 lbs$ 22,50013,500405,000$ 7,500412,500
1003006,000 sq ft90 acres$ 30,0004,500 lbs$ 45,00027,000810,000$ 15,000825,000
20060012,000 sq ft180 acres$ 60,0009,000 lbs$ 90,00054,0001,620,000$ 30,0001,650,000
Sheep can give Birth 6+ lambs every Two Years
Sheep can Produce 1/2 Gallon Milk per day / 180 Day Lactation
Raw Sheep Milk $9 - $25 per Quart - Used $ 30 per Gallon for Table
Feed 5 Months Buying Hay $ 100 rest Grazing
Please Check my Numbers

18 Breeds of Hair Sheep FAQ Table

Hair Breeds of SheepCountry OriginPurpose of BreedUseEwe Weight
KatahdinsCaribbean / Maine / AfricaTo Graze Power lines / instead of ChemicalsMeat120 - 160 lbs
DorperSouth AfricaThrive in Africa / Hot ClimateMeat / Fast Growing230 LBs
BlackbellyAmericaHot ClimatesMeat150 LBs
St. CroixCarribeanCame on Ships for Meat for sailorsMeat150 lbs
RomanovsRussiaPrimarily for MeatMeat
Wool - Double Coated
110 lbs
Blackhead PersianAfrica / SomailaBred for High Quanity of FatMeat120 lbs
West African DwarfSouth / Central AfricaMeat55 lbs
Red MaasiEast AfricaBred for Hardiness and parasite ResistanceMeat77 Lbs
Wiltshire HornEngland Do not suffer from FlystrikeMeat149 lbs
Royal WhiteUnited States / TexasBred for Tender Meat and Disease ResistantsMeat175 lbs
California RedNot completely Hair sheep/ Combination of both/ Prod 2 lambs YrMeat140 lbs
DamaraEgyptVigorous with fast growing / in extreme conditionsMeat110 lbs
PelibueyCuba / MexicoTropical SheepMeat75 lbs
AfricanaColumbia / VenezulaMeat110 lbs
MoradaBrazilSurvive ScrubMeat66 lbs
Brazillian SomailaSouth Africa / SomaliMeat
UdaAfricaLong Legged SheepMeat88 lbs
TouabireAfrica Dairy / Meat77 lbs
Breeds - Origin - Purpose - Weight

Minature Breeds of Sheep

BreedHeightWeight / Full GrownFood Per DayLifespanWool / Hair SheepCost
Quessant Sheep!8"28 - 30 Lbs1/2 - 1lb 10 - 12 YrsWool$ 350 - 450
Baby Doll Southdown18"75 lbs2 - 3 Lbs10 - 12 YrsWool$ 350 -450
Southdown Sheep18" - 24"130 lbs6 - 6 lbs10 - 12 YrsWool$ 180 - $ 600
Cheviot Sheep 20"130 Lbs6 - 6 lbs10 - 12 YrsWool$ 180 - $ 600
Border Cheviot20"130 lbs6 - 6 lbs10 - 12 YrsWool$ 180 - $ 600
Shetland Sheep24"75 - 100 lbs6 - 6 lbs10 - 12 YrsWool$ 50 - $100
Navajo - Churro20"110 lbs6 - 6 lbs10 - 12 YrsWool$ 200
Breed of Sheep and Physical Charistics
Amount of Food they Need
Wool - They Need to be Sheared Hair Sheep - Do not Grow Woll but shed Hair once a year
Pricing Depend whether you just want Sheep Or you want to Breed

Toxic Plants for Sheep Pastures

Toxic / Poisonous Plant Symptoms / Characteristics
Garden IrisRoots and stems
HollyBerries - Diarrhea - vomiting - stupor
Morning Gloryhallucinogenic seeds
RhubarbLeaves - Convulsions and Death
Wild CherryWilted Leaves have Cynaide - Convolusions, Rolling Eyes, Tongue hanging, animal dies within hours
YewNeedle Like Shrub - vomiting, convulsions, animals Rarely survive this poisoning
OaksAcorns, young trees - anorexia, constipation diahreah thirst gastro problems
Mountain LaurelSame symptoms of Poiaoning. Vomiting, Diahreah, salivation - Usually fall into Coma and then Death
RhododendronSame symptoms of Poiaoning. Vomiting, Diahreah, salivation - Usually fall into Coma and then Death
AzaleaSame symptoms of Poiaoning. Vomiting, Diahreah, salivation - Usually fall into Coma and then Death
List of Poisonous / Toxic Plants
many of these are found around Fence Rows
Fields Should be Checked

Sheep Associations 10 Breeds of Sheep

Breeds of SheepCountry OriginPurpose of BreedUseEwe WeightAssociation For Info
Suffolk SheepBritian / SuffolkFast GrowingMeat250 - 350 LbsUnited Suffolk Sheep Association
Merino SheepSpainSoftest WoolWool100 - 200 LbsAmerican and Delane Merino Sheep Association
HampshireBritainBest Tasting MuttonWool / Meat200 LbsAmerican Hampshire Sheep Association
RomneyEngland / Romney MarshDisease ResistanceWool / Meat225 - 275 LbsAmerican Romney Breeders Association
Lincoln SheepEnglandProduce Longest Fleece In WorldWool250 - 350 LbsNational Lincoln Sheep Breeders Association
Dorper SheepSouth AfricanFast Growing MeatMeat230 LbsAmerican Droper Sheep association
Turcana SheepRomainiaAdapted Alpine PastureWool / Milk / Meat175 - 200 Lbs?
Rambouilette SheepFranceStrong / Hearty / All ClimatesWool / Meat300 LbsAmerican Rambouilette Sheep Breeders Association
Leicester LongwoolUnited KingdomFast growing / Good FleeceWool200 LbsLeicester Longwool Sheep Breeders Association
Breeds - Origin - Purpose - Weight

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