Breeding Angus

Buying bulls is an important part of running a beef herd. Bulls contribute greatly to the returns of a commercial herd. They should be considered as an investment rather than a cost of production.

Index (click on the links below)

1. WHAT DOES A BULL DO? . . . . . . . . . . . . . . . . . .Top of Page

A bull’s role is to get cows pregnant and produce calves that meet your market requirements. In basic terms, a bull is a self propelled semen production and delivery machine, with a built-in heat detection mechanism. If a bull is sound and well maintained, he will continue to carry out this role for at least five years before needing to be replaced. He will have a workload capacity allowing him to be used with a large number of females every year. A bull should also pass on genetic characteristics to his offspring to ensure that they meet market targets and produce suitable replacement females for the breeding herd.

These requirements mean that a bull must be structurally sound to last a full working life and fertile enough to meet the needs of a high mating load of up to 50 cows or more each year. In buying bulls we need to check indicators of fertility and structure, selecting bulls that will last and rejecting those that will not.

Increasingly, information is provided on sale bulls to assist buyers make informed decisions. The following information may be provided:

2. BULL FERTILITY . . . . . . . . . . . . . . . . . . . . . . . . . .Top of Page

There are two main components to bull fertility, the testicles and serving ability:

(a) Bulls with larger testicles have higher conception rates, larger work loads and breed more fertile daughters. A minimum size of 34 cm scrotal circumference by 18 months of age is recommended. The testicles should be assessed for size, shape, firmness and freedom from abnormalities by a competent assessor.

(b) Serving ability or serving capacity information is useful to ensure that a bull is capable of serving and has adequate libido.

3. STRUCTURAL SOUNDNESS. . . . . . . . . . . . . . . . .Top of Page

All bulls should be assessed for structural soundness, with attention feet, legs, stance, shoulders, hocks, sheath, mobility, and jaws. You should decide if the animal is acceptable or unacceptable for each of these characters. Bulls that are unacceptable are more likely to break down so remove them from the potential purchase list.

4. PHYSICAL MEASUREMENTS. . . . . . . . . . . . . . . .Top of Page

Actual physical measurements such as sale weight, eye muscle area, fat depth, growth rate, frame score and muscle score are often provided on sale bulls. Take care in using these measurements as they can be heavily influenced by feeding and environment. They can be misleading as true indicators of genetic merit, particularly if the bulls come from different properties.

Despite the influence of environmental effects, physical measurements can assist your purchasing decisions.

5. THE GENETIC PACKAGE. . . . . . . . . . . . . . . . ... . . . . . . . . . Top of Page

Assessing the genetic package a bull will pass onto his offspring is often more difficult than assessing structural aspects. Some of the physical traits already mentioned are of limited value as indicators of genetic merit. Much more useful information is provided by recording differences in performance among animals run under the same conditions. If differences are observed in situations where animals are given the same opportunity to perform then it is more likely that the differences are due to variation in genetic merit.

Estimated Breeding Values (EBVs). . . . . . . . . . . . . . . . Top of Page

Performance records collected by Angus breeders are analysed through Angus GROUP BREEDPLAN. This system uses all the available pedigree and performance information from each herd to calculate Estimated Breeding Values (EBVs) for each recorded animal. These EBVs are the best estimates of an animal’s genetic merit for the traits analysed.

In the calculation of EBVs, the performance of individual animals within each herd, or contemporary group, is compared to the average performance of others in that herd, of the same age, run under the same conditions and treated equally.

With the extensive use of AI and the trading of performance recorded breeding stock amongst Angus herds, a network of pedigree links has been established enabling the adjustment for environmental differences between herds, years and management groups. This allows comparisons between animals from totally different environments, even between Australia and New Zealand.

EBVs are expressed in the units of measurement for each particular trait, and are shown as +ive or -ive differences from the breed base. For example, a bull with an EBV of +75 for 600-day weight is estimated to be genetically 75 kg heavier than the breed base of zero. Since the zero breed base is set to a historical benchmark, the average growth EBVs of animals in each year drop has changed over time as a result of genetic change within the breed. Animals should be viewed as “above average” for a particular trait only if their EBVs are above the EBVs for their particular year drop.

The average 600-Day Weight EBV for 2004 born calves was +75 kg. Consequently, a bull born in 2004 which has an EBV of +75 kg is average compared to his year drop.

Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Top of Page

EBVs are based on the performance information on an animal and its relatives available at the time of calculation. They are not static figures. EBVs change over time as more information becomes available.

The “accuracy” value of each EBV gives an indication of how reliable the particular estimate is and how likely the EBV is to change as more information becomes available. For example, a bull at two years of age will have EBVs based on his own performance and the performance of his brothers, sisters, parents and other relatives. As that bull is used and has progeny of his own, more information about his genetic merit becomes available. His EBVs may change and because of more total information, the accuracy of the EBVs will increase.

Accuracy levels are also influenced by the heritability of the trait. For lowly heritable traits, more records are needed to give a similar accuracy to that of a highly heritable trait.

Accuracies are expressed as percentages. The higher the percentage value, the greater the confidence that the EBV is an accurate estimate of the individual’s breeding value and the less chance of it changing as more information becomes available. Even though an EBV with a low accuracy value may change as further information is recorded, it is still the best estimate of an animal’s genetic merit at any given time. As more information becomes available, an EBV is just as likely to increase as it is to decrease in value. Young animals will not have accuracy figures above 80% and this is considered moderate only.

Deciding what you want

To buy a bull that meets your needs, you must first decide on your priorities. This means thinking about the market you are aiming at, what you need to change to improve the suitability of your sale stock, and what you want to change about the females in your herd. The answers to these questions become part of your shopping list. The important thing is not to make your list too long. Concentrate on the economically important traits.

Understanding EBVs

EBVs are commonly included in catalogues for Angus sales. Current EBVs for all performance recorded animals are available on the Angus Australia website. In addition, Angus Australia publishes an annual GROUP BREEDPLAN Report, which lists the EBVs for major sires used in the Angus breed. The following examples explain how to use the EBV information.

In this case, two bulls for sale in 2006, were born in 2004. Bull A is above average for all the weight EBVs and slightly below average for milk EBVs when compared to average of 2004 born calves.

Birth Weight - This EBV is the best predictor of the birth weight of a bull's progeny. Bull A is well above breed average, and would produce calves averaging 2kg heavier than bull B if joined to similar cows. (There is a 4kg difference in birthweight EBVs between the bulls. Half of this - the sire's contribution - will be expressed in the calves.)

Birth weight is by far the most important genetic influence on calving ease. Calf shape and pelvic area of the cow are also important. There are also many non-genetic influences on calving ease like nutrition.

Milk - GROUP BREEDPLAN partitions weaning weight into the growth and milk components. The Milk EBV gives an indication of the extra weaning weight of the progeny of a bull's daughters that can be attributed to differences in milk production. Bull B is well above breed average for Milk EBV and would have the best milking daughters. The difference here would obviously only influence a buying decision where the level of milk production needs improving. In some situations high milk production can be a disadvantage as females may have difficulty getting back in calf.

200, 400 and 600-Day Wt - these EBVs predict weight at various ages, so are most useful in turn for vealer, yearling or heavy steer producers. Bull A is ahead in all these areas, and would produce on average, calves heavier by 13kg, 23kg and 30kg as vealers, yearlings or 20 month old steers, respectively compared to bull B.

Mature Cow Size – Mature cow weight EBVs indicate the size to which progeny will grow by 5 years of age.

While moderation in cow weights is desirable for reducing herd feed costs, it is often associated with lower overall growth potential. Mature cow weight and early growth need to be carefully balanced to optimise overall herd performance. In the example, it would be expected that, on average, the daughters of Bull A would weigh 35 kg heavier as mature cows than the daughters of Bull B (if reared and subsequently run in the same environment).

BULL SELECTION EXERCISES. . . . . . . . . . . . . . . . . . .Top of Page

Test your knowledge on growth and milk EBVs by attempting Exercise 1. Assume all bulls have passed your physical soundness examination and have similar accuracies for each of the EBVs.

The following buyers are selecting from this sire list. Which bulls should they choose?

Buyer 1 - Has a herd of crossbred cows with no calving problems and wants a bull to produce fast growing vealers. Heifers are not kept.

Buyer 2 – Wants a bull to join to Hereford heifers to reduce calving difficulty. Calves are grown out for sale as yearlings.

Buyer 3 - Wants to increase yearling and final weights and avoid calving difficulty. The main product is heavy steers. Replacement heifers are retained.

Buyer 4 - Is straightbreeding in a harsh environment where cows with high EBVs for milk are slower to rebreed. Increased growth rate in two year old steers is also an objective.

CARCASE TRAIT EBVs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Top of Page

Angus GROUP BREEDPLAN includes carcase trait EBVs covering both meat quality and yield traits. These EBVs are calculated from abattoir carcase records and ultrasound scans taken on live animals. Measurements of carcase weight, subcutaneous fat depth at the 12/13 rib and P8 rump sites, eye muscle area, retail beef yield and intra muscular fat % (marbling) are used. Apart from the carcase weight EBV which is adjusted to a standard age, all other EBVs are adjusted to a 300 kg carcase for comparison.

Carcase Weight EBVs are estimates of genetic differences in hot standard carcase weight at 650 days of age. Differences in carcase weight EBVs are estimated from available abattoir carcase weight data and known genetic associations with growth traits.

Larger, more +ive carcase weight EBVs are more favourable. For example, a bull with an EBV of +40kg would be expected to produce progeny with heavier carcases at 650 days than a bull with an EBV of +20kg.

Eye Muscle Area (EMA) EBVs are measured in square centimetres, and indicate genetic differences in the size of the eye muscle on a standard 300 kg carcase. EMA has a positive relationship with retail beef yield. Progeny of animals with higher EMA EBVs will tend to have superior visual muscle expression. Larger, more +ive EMA EBVs are desirable.

Rib Fat and Rump Fat EBVs are expressed in mm. They are estimates of genetic differences in subcutaneous fat cover at the 12/13 rib or at the P8 rump site on a standard 300 kg carcase. Bulls with higher positive figures will tend to sire fatter (or earlier finishing) progeny than bulls with lower or negative EBVs. Selecting desirable fat EBVs depends on what you need to change. Lower, negative fat EBVs will take fat off carcases, make animals harder to finish and increase carcase yield. For long fed markets, this is generally desirable.

Retail Beef Yield % (RBY%) EBVs are estimates of genetic differences between animals in percentage retail yield in a standard 300 kg carcase.

RBY% reflects economic differences in carcase yield and refers to the bone-out yield of a carcase, with primals trimmed to 2-3 mm fat, and meat trim adjusted to 85% chemical lean. Higher, +ive EBVs are generally desirable and will result from more muscle and less fat.

Intra-muscular Fat % (IMF%) EBVs indicate genetic differences in intra-muscular fat or marbling measured at the 12/13 rib of a standard 300 kg carcase.

For markets where marbling is important (eg CAAB, Japanese B2/B3), differences in IMF% can contribute significantly to carcase value. Sires with higher IMF% EBVs are expected to produce progeny with higher average marble scores than sires with lower IMF% EBVs. See exercise II below

Which bull should the following clients buy?

Client 1 - Sells yearling steers to a feedlot which is long-term feeding for Japan and has been advised to increase size and growth, reduce fatness and maintain or improve muscularity and marbling.

Client 2 - Breeds steers from European x Dairy cross cows and has difficulty in finishing them for sale as yearlings.

Client 3 – Sells heavy weaner steers and heifers to a feedlot for finishing into the heavy domestic supermarket where they are paid on yield and quality grade.

FERTILITY EBVs. . . . . . . . . . . . . . . . . . . . . . . . . . . .Top of Page

The male fertility trait, Scrotal Size (SS) is an indicator of male fertility, but more importantly, high SS bulls are known to breed more fertile females. EBVs for the female fertility traits - Days to Calving (DC), Calving Ease and Gestation Length (GL) are also available for Angus breeders.

Scrotal Size EBVs are expressed in cm. Bulls with high figures will breed sons with bigger testicle size and daughters with earlier puberty and shorter calving intervals.

Days to Calving EBVs indicate the fertility of a sire’s daughters. EBVs are expressed in days, and predict the time from the start of the paddock joining period until the cow calves. Sires with negative DC EBVs are preferred as they will breed daughters with shorter calving intervals and therefore higher fertility.
See exercise III

Buyer 1 - Has a commercial straight bred Angus herd turning off two year old steers and seeks to improve female fertility, while maintaining heavy steer weights.

Buyer 2 - Intends to use the bull as a terminal cross over cross bred cows, selling both the heifers and steers as finished yearlings.

Buyer 3 - Wishes to increase scrotal size in her stud herd. Yearling bulls are sold and in the past some have been marginal for scrotal size. Clients are predominantly breeders of yearling steers.

CALVING EASE EBVs. . . . . . . . . . . . . . . . . . . . . . . .Top of Page

Angus GROUP BREEDPLAN includes Calving Ease EBVs, estimated from birth weight, calving ease scores and gestation length. Two EBVs are published and more positive EBVs are desirable indicating more calving ease:

Calving Ease Direct (DIR) - A measure of how easily a sire's calves are born. This reflects differences in birth weight and calf shape.

Calving Ease Daughters (DTRS) - A measure of how easily a bull's daughters calve.
See Exercise table IV below

“Calves that are born easily and grow quickly to meet market requirements are the key to commercial profits.”

Client 1 - Has a herd of easy calving mature Brahman cross cows, selling yearlings on improved NSW north coast country. The bull will be used as a terminal sire.

Client 2 - Has a group of British breed heifers being joined on improved temperate country. All calves, including heifers, will be grown out for sale as yearlings.

Client 3 - Has an Angus stud. He wishes to improve yearling weight and calving ease, without going above current breed average for birthweight.

As well as assisting bull buyers, Angus GROUP BREEDPLAN has an important role in AI and ET. These techniques quickly spread 'superior' genetics, so it is imperative that only top cattle are used. Whether it is growth rate, fertility or calving ease, Angus GROUP BREEDPLAN will greatly assist in identifying the right cattle.

With the wide range of traits recorded and the number of EBVs available, balancing the various traits is important. The number of traits measured assists us to identify animals with well balanced performance across the full range of traits.

Indexes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Top of Page

The number of EBVs available can make it difficult to decide which animal fits your requirements best for a particular market. Indexes can help as the indexes weight the different EBVs based on their impact on the financial return of a commercial herd aiming at a particular market. The indexes are expressed in $ per cow joined and using one indicator index figure can make selection decisions easier.

Four standard indexes are available for all animals on Angus Australia database through its website EBV Enquiry.

Client 1- Has a self-replacing herd in southern Australia. Sends steers to a feedlot where they are fed for 300 days. Feedback reports have shown the herd’s marbling performance needs to improve considerably.

Client 2- Has a self-replacing herd in southern Australia, turning off steers for the domestic supermarket trade. Is looking for a bull to join to heifers.

Answers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Top of Page

Exercise I

Buyer 1 - Bull C (The high Birth Wt and low Milk EBVs do not matter, so select the bull with the highest 200-Day Wt EBV.)
Buyer 2 - Bull A (Lowest Birth Wt EBV and acceptable 400D weight)
Buyer 3 - Bull B (High 400 and 600-Day Wt EBVs, acceptable Birth Wt and Milk EBVs)
Buyer 4 - Bull D (Adequate 600-Day weight EBV and below average Milk EBV)

Exercise II

Client 1 - Bull B (Fat EBVs are negative; IMF%, EMA and RBY % positive; Carcase Wt EBV is also high)
Client 2 - Bull A (Fat EBVs are positive)
Client 3- Bull B (High Carcase Wt and RBY% EBV)

Exercise III

Buyer 1 - Bull A (The highest priority is the negative (short) DC EBV, and 600- Day Wt EBV is also good)
Buyer 2 - Bull D (Fertility EBVs are not important, so select highest 400-Day Wt EBV)
Buyer 3 - Bull E (Has the highest SS EBV and a good 400-Day Wt and DC EBVs)

Exercise IV

Client 1 - Bull C (Highest 400-Day Wt EBV. With easy calving cows, the high birth weight EBVs and negative Calving Ease DIR EBV do not matter)
Client 2 - Bull D (Good Calving Ease DIR EBV, good growth EBVs, no heifers kept so Calving Ease DTRS not a worry )
Client 3 - Bull D (Positive for Calving Ease DIR and DTRS EBV, Breed average for Birth Wt EBV, above average 400-Day Wt EBV)

Exercise V

Client 1- Bull D ( highest Japan B3 Index and highest IMF% EBV)
Client 2- Bull C (Bull A and B with the higher Supermarket $ Index are eliminated because of their high birth weight EBV).

Buying Angus Bulls