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Livestock Growth and Development

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Carrie Whyte

on 28 October 2012

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Transcript of Livestock Growth and Development

Growth refers to increase in
size until
maturity is reached Growth Development Growth Management
Practices What is a terminal
sire? Breeding Value (BV) Development Development refers to the
physiological changes
associated with growth until
maturity is reached,
or until the product leaves the
grower's control Demonstrate understanding of how NZ commercial management practices influence livestock growth and development Management practices used in commercial livestock production refers to actions taken
that impact on the quantity, quality,
timing, and economics of production. a sire used in cross-breeding,
whose progeny will possess a
high rate of growth and good
carcass quality, but will not be
suitable for breeding themselves The variation in performance between
individual sires is huge. Selecting on breed
or appearance is no guarantee of obtaining
a high performing ram. Theoretically, rams
could be selected sight unseen on their BV
for whichever characteristics you are seeking. We also need to understand early vs late maturing sire breeds......
Have a look at the NZ Sheep Breed poster and Sheep Breed information booklet.
Decide which breeds of sheep are good sire breeds.
Write down:
the breed name
main attributes What are some management practices that can affect livestock in either a positive or negative way?????
2 minutes to write down as many MP as you can think of. Management Practices include :

Drenching
Vaccinating
Shearing/Crutching
Castrating
Scanning
Condition scoring
Providing quality feed
Housing
What about breed selection?
Crossbreeding? Cross-breeding of Sheep

The technique of cross-breeding is long established and there are opportunities for its wider use in NZ.
The benefits are the exploitation of hybrid vigour, rapid short term gains and flexibility to meet changing economic conditions and markets. Cross-breeding can.....
introduce traits that are not present in the existing breed (these might include greater milking ability, improved lambing percentage, growth rates, hardiness and disease resistance.
make rapid changes to product mix. It may be possible to move into a completely different sector of the wool or lamb market.

Cross-breeding can, however.....
Introduce traits that are not wanted, or reduce performance of some traits of the existing flock.
introduce a lot of variation in the flock, influencing culling decisions Cross-breeding can not....
make up for inadequate feeding or management
overcome very poor genetic merit in the base flock. The cross-breeding result will always be better if good representatives of each breed are used
eliminate major faults What is an early maturing animal?

Does it mean the animal develops and grows quicker?

What benefits could there be to having livestock mature earlier? What benefits could there be to having a ram mature earlier?

Relating back to our assessment specifications: The use of early and late maturing sire breeds, think about growth and development. What is hybrid vigour?

When genetically different animals are crossed, the recombination of genes often lead to increased growth and production. This effect is called heterosis or hybrid vigour, and can be measured by comparing the performance of the offspring with the average of the two parents.

Sometimes the offspring can be worse than the average of the parents, an effect called negative heterosis. Significant hybrid vigour will occur only when two genetically different parents crossed, and in general it will be greater the more widely the parents differ in their genes. HYBRID VIGOUR (HETEROSIS)

When two dissimilar breeds are mated hybrid vigour is likely to occur. The progeny from this mating are likely to perform at a higher level than the average of the parents performance. This is individual hybrid vigour.

Hybrid vigour is also exhibited by the F1 ewe in some traits such as milk production and mothering ability. This means her progeny can also perform
better eg. Heavier weaning weights, better lamb survival.

I Individual Hybrid Vigour
Breed A produces 4 kg wool
Breed B produces 5 kgs wool
The F1 produces 4.86 kgs wool
The average production of A and B would normally be expected to be 4.5
kgs.

The increase in production due to hybrid vigour is 4.86 – 4.5 = .36 kgs
This is equal to .36 ÷ 4.5 = 8% The early maturing animal, characterised by a high average daily weight gain from birth to weaning.
These animals grow fast while on their mothers and tend to plateau after weaning.

The later maturing animals are characterised with a lower birth to weaning weight gains and an
ongoing growth pattern thereafter. A crossbred is an animal whose sire (father) and dam (mother) are of different breeds or breed types, while a purebred animal's parents are of the same breed or type. A registered or pedigreed animal has a known ancestry. What is the purpose of the sire?

to breed replacement stock
to produce offspring for breeding
to produce offspring for slaughter Ewe Breed Selection

The most important factors to consider when selecting a ewe breed, type, or cross are:

1. Adaptability to the production environment
2. Type of coat or wool
3. Level of reproduction
4. Timing and frequency of lambing
5. Level of care Ram Breed Selection

Before choosing a ram breed, you first need to determine his primary purpose. Will he be used to sire market lambs or do you want him to sire ewe lamb replacements? Or both? For producing replacements, you need a ram with the appropriate type of wool/coat and reproductive characteristics.
For market lamb production, you need a ram that will sire lambs that are suitable for your target market(s). 1.Using the diagram = Explain the changes in the bull’s body shape in regards to
a) growth
b) development 2.Using Fig 10.8 and 10.9 =
a) Explain what the terms “high plane” and “low plane of nutrition” mean.
b) How does the information from these graphs impact on the farmer’s management practices of feeding lambs/calves to achieve better production? EM animals are characterised by a high average daily weight gain from birth to weaning, i.e. they grow fast on their mothers and plateau after weaning
LM animals have a lower birth to weaning weight gain however, have on ongoing growth pattern thereafter.
Both EM and LM have their advantages and disadvantages and again it comes down to the farms objectives as to if an EM is going to be more profitable as opposed to a LM.
As an example EM breeds start to lay down fat tissue at an earlier age, this if not selected for could cause implications on carcass grading, age of slaughter etc. Early vs. Late Maturing Breed selection will be determined by the product(s) the farmer is producing, the area in which they live, and the overall goals or objectives of the farm.
Different breeds suit different situations and therefore ensuring correct selection for the situation/end purpose is very important.
Breeds differ in a number of ways
EM vs. LM
Ease of birth
Fecundity (litter size)
Carcass composition
Mothering ability
Temperament
But also with regards to sheep wool/meat/dual purpose producers.
For cattle – dairy/beef production. Breed Selection More control to ensure the five freedoms are met?
Control the temperature
Disease management
Ventilation
Control feed intake
Ensure social orders are met (allowed to display normal patterns of behaviour)
More control to reach target weights under a controlled environment Advantages of housing Discussion Points:

What are some environmental conditions NZ livestock are exposed too?
When are stock most vulnerable?
What can be done? Controlling environmental conditions Work on sheep farms (high, hill and lowland)
is largely regulated by the seasons.

Winter
In winter, most sheep farms carry their lowest number of stock. In the high country and harder hills, farmers feed hay and silage to supplement the animals’ diet. On easier country, sheep are break fed (a feeding method where animals are fenced into part of a paddock) on fodder crops and saved pastures. Farms that specialise in finishing sheep for meat production continue to supply the butchers’ market and export trade.

Ewes are scanned to check for pregnancy. Barren ewes are culled, while those carrying twins or triplets are given preferential feeding. The seasonal round Lowlands
The plains, river valleys and easy rolling hills of the North and South Islands are the home of intensive sheep farming (fattening farms). In the 2000s, this land has been increasingly given over to dairy farming and horticulture, and in some areas vineyards. Lowland farmers generally finish stock bought of the hill and high country on fodder crops and special pasture mixes. Cattle and sheep studs are also farmed on lowland country.
These farms are highly fertile and of high carrying capacity. Medium hill country
This is used to finish lambs and older sheep for the meat
trade, also wool is still an important product.

Easy hill country
This type of terrain allows farmers more flexibility in their production choices. Many breed and finish sheep and cattle. In good seasons, farmers on easy hill country also buy in stock for finishing. Cross-breeding to improve productive traits is becoming more common. The easy hills are also the home to stud sheep enterprises – breeding rams for the hard and medium hill country Hill Country

Hill country makes up vast area of pastoral land in the North and South Islands. North Island hill country has traditionally been dominated by Romneys. In the South Island, the halfbreed and Corriedale are found in the drier areas, and the Romney in wetter parts. Rams are usually the only stock bought in.

The hill country can be further subdivided into three classes – easy, medium and hard – according to the steepness of the hills and the length of the growing season.

Hard hill country

On hard hill country, farmers run breeding stock. Their income is from wool and the sale of store sheep (sheep to be fattened for slaughter) and cattle to be finished on the easier hills and lowlands. The Perendale was bred to replace Romneys in this type of country. The farmer who sold the lambs in Pen B used a method that makes ram lambs infertile, but does not involve the removal of the testicles. These lambs are called “cryptorchids”.

Describe the method used to change a ram lamb into a “cryptorchid”.
Explain how use of the method you described in (i) improves the economic returns
from lamb production. Previous Exam Question Farmers need to decide whether to grow lambs as entire males, cryptorchids or as wethers.
Facts
Cryptorchids grow almost as fast as entire male lambs.
Both cryptorchids and entire male lambs have less fat than wethers so are leaner.
Cryptorchids are easier to handle and fight less in the yard.
Cryptorchids are easier to shear and crutch.
Cryptorchids avoid hygiene problems with genitalia. Wether, Ram or Cryptochid lambs? The GR measurement is a standardised measurement (in mm) used in the meat processing industry to determine which carcasses are to be graded overfat. In lambs, it is the tissue depth between the carcass surface and the rib, taken in the region of the 12th rib, at a point 11cm from the carcass midline. GR measurement Abstract
Growth rates, carcass composition and management problems of "short scrotum" rams (made by elevating the testes to a position against the abdominal wall using rubber rings), wethers and entire male lambs were compared on a hill country property in northern Hawkes Bay. Of 3 groups of 65 Perendale lambs selected randomly at docking at about 4 weeks of age, 1 group was left entire, 1 was made short scrotum and the other was castrated. The lambs were weaned at about 10 weeks of age, separated from the main flock at about 14 weeks of age and thereafter kept as 1 flock until slaughter at 9 months of age. They were weighed every 6 weeks from 14 weeks of age. After the removal of 6 lambs from each group for detailed investigation at Massey University, the top 50 lambs from each group were slaughtered and their carcass characteristics recorded.
Short scrotum rams showed management advantages over normal ram lambs. They were easier to handle, and avoided the works hygiene problem of dirty genitalia. Short scrotum rams had an overall live-weight advantage of 3kg over wether lambs. This was found not to be due to fat deposition, as short scrotum rams showed a significantly lower GR of 3.3mm, compared with normal rams (4.6mm) and wethers (6.2mm), as predicted by regression for lambs of 32kg live weight. There was no significant difference in carcass weight or dressing percentage between lambs of this live weight, although more normal rams and short scrotum rams fell into heavier grades than did the wether lambs. In detailed investigations on 6 lambs from each group, no differences were found in muscle:bone ratio or fat distribution between the groups. Short scrotum rams had very low fertility; 50 of 56 had no epididymal sperm reserves and 6 had extremely low sperm production. Most sperm from short scrotum rams were abnormal. Short scrotum rams had significantly lighter testes and epididymides than normal rams. Short scrotum rams had plasma LH levels intermediate to normal rams and wethers. Differences between entire and short scrotum rams in testosterone levels varied inconsistently A study of short scrotum, castrated and entire ram lambs A cryptorchid lamb is a lamb which has had his testes forced back into the pelvic cavity and held there by a rubber ring over the scrotum.

These lambs grow almost as fast as entire male lambs because they retain their testosterone producing ability, however the operation (when carried out properly) stops sperm production, making management on the farm easier i.e. no unwanted pregnancies. Cryptochid lambs The need for castration is based on the management of the farm and demands of the market place. Ram lambs grow faster than ewe and wether (castrated) lambs and when ram lambs are marketed at a young age (less than 6 months), commercial lamb buyers usually do not discriminate in price.

It is usually not necessary to castrate ram lambs for the freezer (or locker) trade or when selling lamb directly to consumers, as there is no siginificant difference in the taste or tenderness of the meat from a young ram lamb versus a wether or ewe lamb. Older rams may have a slight taste difference.

During harvest, it is more difficult to remove the pelt (skin) from a ram lamb, especially one that has started to develop secondary sex characteristics. Ram lambs that cannot be marketed by the time they are six months old should be castrated.

On the other hand, wether lambs are easier to manage and eliminate the possibilities of early and/or unwanted pregnancies. When ram lambs are kept intact, it is necessary to wean and separate them from their dams and female pen (or pasture) mates by the time they are 4 months of age. If this cannot be done, ram lambs should be castrated.

Male lambs sold for grazing or as pets should be castrated as they will be easier to manage. Castration Banding

As with tail docking, there are many techniques that can be used to castrate ram lambs. An elastrator band can be placed around the neck of the lamb's scrotum. Care should be taken not to place the band over the lamb's rudimentary teats. Banding will cause the scrotum to shrivel up and fall off in two to three weeks. As with docking, the scrotum may be removed after a few days. Both testicles must be below the placement of the band. If one testicle is missed, it will be retained in the belly cavity, resulting in a "bucky" lamb.

Castration by banding causes some pain to the lamb, but the pain is short-lived. Lambs should be castrated at a young age, preferably between 1 and 7 days of age. Castration Where to dock Read through the ‘Dehorning Cattle’ sheet.

Copy down the notes on ‘Why dehorn cattle?’
Copy down notes on ‘When to dehorn’
Make summaries of two of the methods of dehorning Dehorning methods Horn injuries can cause lacerated wounds and bruising in cattle. Horned animals in dairy herds often disturb other cows at milking with a resulting loss of production. It is now a legal requirement that horned cattle are penned separately for transport.

Removal of developed horns is a traumatic operation so they are best removed as early in life as practicable. Under the Welfare Act (1999) it is an offence to dehorn any animal older than 9 months unless with an anaesthetic. Disbudding/Dehorning Docking, castrating, and disbudding are management practices routinely performed on farms. Each producer needs to decide whether or not to perform these practices, when to do them, and how to do them. Maintaining a high standard of animal welfare should be a consideration in all decisions related to docking, castrating, and disbudding. Docking, castrating and disbudding Consign dehorned cattle only
Avoid forcing stock through gates
Avoid prodding, poking or hitting stock
Avoid overcrowding in yards and trucks
Tie dogs as they can excite stock excessively
Ensure yards are well maintained with no loose nails, sharp corners
Dag and eye clip woolly lambs several days ahead of despatch
Never lift lambs by the wool
Hold stock off feed for several hours to empty bowels before loading them Stock handling techniques Stock move better in cool weather, so early morning is an ideal time to work with animals.
Dogs are an essential tool, but must be under control. When not in use they should be confined or tied up to prevent unnecessary stress to livestock.

As we have already stated wounds, bruises and contamination are the principal reasons for the downgrading of meat from stock consigned for slaughter.

Most of these losses can be reduced by improving stock handling and care. Mustering and Yarding EM – reaching an ideal market condition (muscle, meat/fat ratio, etc) at an earlier age than average. EM lambs do not grow any faster than late maturing ones, so they are smaller and lighter in weight when marketed.

Advantages of EM breeds:
Higher stocking rates
EM breeds are smaller therefore, smaller framed animals require less feed to maintain and improve their condition
Shorter production times
Lower production costs Back to EM vs. LM Animals attain target slaughter weights earlier
More efficient use of feed
Lower fat content
Financial benefits of great yields of ‘harvested’ productions
What about management benefits……


In summary: to increase farm profitability, production costs must be minimised while the returns to the producer are maximised Reasons to achieve high animal growth rates quicker: Examples of EM sheep breeds include: Dorset Down, English Leicester, South Dorset, South Suffolk.

Examples of LM sheep breeds include: Cheviot, Suffolk, Southdown and Wilshire Horn.

Slightly off topic……
Why would farmers want to achieve high animal growth rates for productivity quicker? Keeping stock indoors is common practice in piggery/hatchery situations. They don’t need to be kept for intensive farming purposes although these are common.

Why house?
The Animal Welfare Act 1999. Understand the ‘five freedoms’
Proper and sufficient food and water.
Adequate shelter.
The opportunity to display normal patterns of behaviour.
Physical handling in a way which minimises the likelihood of unreasonable or unnecessary pain or distress.
Protection from, and rapid diagnosis of, any significant injury or disease. Housing Ewes are mated in autumn. Before mating they are ‘flushed’ – given better feeding to lift their body weight – to increase their fertility. Ewes are usually crutched before mating – the discoloured wool and dags from around the tail are removed. On some farms the belly wool is also shorn so the sheep can move about more freely in wet and muddy conditions.

Ewes and rams are often selectively mated, with the rams chosen to improve particular qualities that the ewe might lack, such as density or fineness of wool, or body size.

Most farmers leave rams with the ewes for up to six weeks. Some farmers fix harnesses with coloured crayons on the rams – as he mounts the ewe the crayon leaves a coloured patch on her rump. After mating, the ewes’ feeding is controlled at a level that maintains their body weight, so farmers can use their feed efficiently and save any surplus for winter. Autumn Lambs are weaned off their mothers at about three months of age. The ewes and lambs are mustered into the permanent yards and drafted (separated into groups). On lowland farms and easy hills, some of the lambs will be ‘prime’ – ready to be killed for meat. The main mob of weaned lambs are drenched, dipped against fly strike and put onto the best pasture available, which on better country might include specialist crops for finishing the animals. Over the summer the lambs are brought in every few weeks and the prime animals drafted off for the freezing works. On hard hill and high country, lambs not required to maintain the flock are sold as stores (animals to be fattened for slaughter) at weaning or grazed for a month or so, before being sold to farmers to be finished on better country.
At weaning the ewes are culled, with the older sheep and poorer types being sold off. Old ewes from hard hills and high country are often bought by farmers on easy country, kept for a year or two, and mated to a terminal sire to breed prime lambs. Summer Farmers who rely on wool as a main source of income shear their ewes before lambing, as the stresses of bearing and raising lambs can weaken the wool and lower its value. In colder regions, sheep are shorn with blades or a cover-comb, leaving enough wool for protection from storms.
Farmers try to time lambing to match the first flush of grass growth, as ewes need good feed to produce milk. On rough country, farmers allocate a certain number of ewes to each paddock or block and leave them to lamb unattended. On easier country, farmers often shift the lambing mob daily, leaving behind the ewes that have recently given birth and their lambs. In this way ewes with lambs are given the best feed available.
A week or two after lambing, ewes and lambs are taken to the tailing yards, where the ewes are separated from the lambs and drenched with an anthelmintic to kill intestinal worms. Each lamb is caught, vaccinated against clostridial diseases (bacterial diseases such as tetanus), and given a worm drench and an ear mark to identify its farm. Then its tail is docked with a sharp knife, searing iron or rubber ring which stops the blood supply. Ram lambs are castrated using a knife or rubber rings. Finally, before the lamb returns to its mother, its rump is sprayed with a chemical to prevent fly strike (flies laying their eggs on a living animal). Spring Is there any expense from a production point of view to those animals living in the high country? Discussion point: The climate and topography of NZ’s sheep farms
have led to differences in farm management.
There are three main types of land:

High Country
High country farms are mainly in the South Island. They are well up in the mountains, therefore have long cold winters and regular snowfalls. The farms have low fertility so pastures are mostly unimproved tussock and random grasses such as browntop. Areas of better soils are cultivated to grow feed crops and improved pastures, often harvested as hay and silage. Irrigation has become widespread for more reliable summer production.

Fine wool from Merino or Halfbreed sheep is the main source of income for high-country farmers. Merinos are the only sheep which can stand up to the rigorous condition. Lambing percentages are low, mortality can be very high in bad snowstorms, and almost the only source of income is wool. These farmers therefore pay much attention to the selection of their rams, as they have almost no scope for culling their flocks, and they take good care that their wool is well prepared for market. It is a highly specialised type of farming. Environmental conditions The cryptochid procedure is also called the "short scrotum method".

The rubber ring is placed around the scrotum with the testicles above it so that they are pushed up against the body wall.

This keeps the testicles at body temperature, so the animal is infertile but still getting the growth benefit of male hormones.

The scrotum shrivels and drops off after a few weeks.

If the procedure isn't done correctly and the testicles aren't held high enough against the body, the animal may not be infertile and could get females pregnant.

There is no advantage in using the cryptochid procedure for buck kids or bull calves because of the management hassles of farming animals that are not fertile but behave like entires. Cryptochid lambs Key Points

Ram lambs grow faster than wethers
If sold off prior to 6 months makes no difference
If kept after 6 months should be castrated
Ram lambs for slaughter not necessary to castrate no significant difference to taste and tenderness
Older rams have a slight taste difference
Rams have a leaner carcass
Wether lambs are easier to manage and prevent early/unwanted pregnancies
If kept intact must wean and separate by 4 months Castration Docking improves the health and welfare of sheep and lambs. It prevents fecal matter from accumulating on the tail and hindquarters of the animal. Tail docking greatly reduces fly strike (wool maggots), while having no ill effect on lamb mortality or production. Docking facilitates shearing. Not many sheep shearers want to shear sheep with long tails. Docking makes it easier to observe the ewe's udder and detect potential problems.

Some markets (lamb buyers) discriminate against tailed lambs, since having a tail lowers the dressing percent (yield) of the lamb and removal of the tail during processing requires extra labour. On the other hand, ethnic buyers of lambs often prefer undocked lambs. Tail Docking Management Practices for livestock growth, development and production In a simple beef finishing system, the most important trait to consider is growth rate, as the sooner the cattle meet target liveweights:
The more efficient the animals are at converting feed into beef
The sooner the monetary returns are received
The more likely the animals will attract early- season premiums
The more likely the producer is to avoid that period of the year when there is a dramatic decline in pasture quality, with corresponding poor cattle growth rates. This gives Al’s within herd EBV for that trait. It is assumed that the average EBV for 600 day weight for the group is 0kg.
Therefore Al’s within group EBV for 600 day weight is:
(760 – 700)kg x 0.3 = +18kg
The computer then uses performance information from Al’s relatives in other management groups as well as known genetic relationships between traits, to fine tune this basic within group EBV so that Al can be directly compared with all animals within the same evaluated population. Once adjustments are made the computer then:
Calculates an average performance figure for the group for each trait.
Compares each individual animal within the group with this average, so that each animal has performance figure, which is above or below the average.
Multiplies this difference from the average, for each animal, by the known heritability of the trait. The offspring of a bull with an EBV for 600 day weight of 130kg will be 65kg heavier and return nearly 15% more profit than the offspring of a bull with an EBV of 0. How does EBV relate to profitability? In assessing an animal’s breeding potential (EBV) we are only interested in the genetic part of production, because this is the only part we can influence through selection.
To find out how big this genetic production is, we multiply the total production advantage Al Capone has over the average animal within his group i.e. 60kg,by the genetic strength of the 600 day weight EBV (its heritability which is 0.3 or 30%) A group of Angus 20 – month bulls have been run together since birth and have been treated the same. The group is weighed at 600 days and their weights are adjusted for age to put them on a level playing field.
Assume the average adjusted weight for the group is 700kg. If one of the heavier animals within the group (Al Capone) has an adjusted weight of 760kg then he is 60kg above the group average. This 60kg is made up of weight due to the activities of Al Capone’s genes (genetic effects) and that due to feeding and animal health etc. Example EBV example An EBV can be generated for any trait as long as there is variation within the trait and the trait is of known heritability.
To develop an EBV, raw data has to be collected from a group of animals that have all been treated the same.
The raw data is then adjusted so all animals within the group are compared on a ‘level playing field’. E.g. weaning weights have to be adjusted for the date of birth of the calves and the age of the cows. EBV’s are expressed in the units of the particular trait. E.g. 600 day weight is measured in kg, scrotal size in cm and calving ease in %. It is a genetic prediction of the average performance of an animal’s progeny or a prediction of how the animal is going to perform as a parent. WHAT IS AN EBV? ESTIMATED BREEDING VALUES EBV’S An EBV is a prediction of the genetic value of an animal as a parent.
The average genetic performance of the offspring of a bull and a cow will be determined by the average of the EBV’s of the parents. However, environmental influences may alter the expression of this.
EBV’s can be used as another tool to select stock for specific systems. To summarise
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