Sunday, February 28, 2010

Online lesson 1(e-learning)

There are many kinds of breeding systems. Well, i have done a research and please read.
Pure-breeding

Pure-breeding is the mating of rams and ewes of the same breed. A purebred flock can be managed as a single flock because all ewes and rams are of the same pure breed. The goal of purebred sheep production should be to supply genetics (seed stock) to the commercial sheep industry. Seed stock are marketed as rams and replacement ewes to other seed stock producers or to commercial sheep operations.

Improvements in purebred sheep should be documented through records. The National Sheep Improvement Program (NSIP) collects performance data from purebred producers and provides them with across-flock EPDs. "EPD" is short for "Expected Progeny Difference."

An EPD is an estimate of the genetic merit of an animal for a given trait. Specifically, the EPD of an animal is the expected difference between the performance of that animal's progeny (offspring) and the average progeny performance of all the animals in the breed for that trait. For example, if a lamb has a weaning weight EPD of 2.0 lbs., this means that its progeny will be 2.0 lbs. heavier than the average lamb in the breed.

Australia's LAMB PLAN is a similar system for determine genetic worth of a sheep. The show ring generally does a poor job of identifying genetically superior sheep, particularly maternal breeds of sheep whose traits cannot be evaluated by visual appraisal.

Out-breeding
Within pure-breeding, there are several types of mating systems. Out-breeding is the mating of animals of the same breed but which have no closer relationship than at least 4 to 6 generations. Out-breeding is the recommended breeding practice for most purebred sheep breeders.

Inbreeding

Inbreeding is a system of breeding in which closely related animals are mated. This includes sire to daughter, son to dam, and brother to sister. Technically, inbreeding is defined as the mating of animals more closely related than the average relationship within the breed or population concerned. The primary genetic consequence of inbreeding is to increase the frequency of pairing of similar genes.

Inbreeding is essential to the development of prepotent animals — animals that uniformly "stamp" their characteristics on their progeny. Inbreeding may also be used to uncover genes that produce abnormalities or death — genes that, in out-bred herds, are generally present in low frequencies. Inbreeding is suggested for only highly qualified operators who are making an effort to stabilize important traits in a given set of animals.

In general, inbreeding results in an overall lowering in performance: vigor, disease resistance, reproductive efficiency, and survivability. It also increases the frequency of abnormalities. For example, the spread of spider lamb disease in black-faced sheep is believed to be the consequence of inbreeding.

Line-breeding
Line-breeding is a system of breeding in which the degree of relationship is less intense than in inbreeding and is usually directed towards keeping the offspring related to some highly prized ancestor. The degree of relationship is not closer than half-brother half-sister matings or cousin matings, etc. Line breeding is a mild form of inbreeding.
Crossbreeding
Crossbreeding is the mating of rams and ewes of different breed compositions. However, it does not denote indiscriminate mixing of breeds, but rather is a systematic utilization of different breed resources to produce crossbred progeny of a specific type. Crossbreeding is used extensively in the commercial sheep industry and the majority of slaughter lambs are crossbred.

Crossbreeding offers two distinct advantages: 1) heterosis; and 2) breed complementarity. Heterosis or hybrid vigor is the superiority of the crossbred offspring. Mathematically, heterosis is the difference in performance between the crossbred and the average performance of the purebred parent.

There are effects of heterosis in the crossbred offspring, crossbred dam, and crossbred ram. In general, crossbred individuals tend to be more vigorous, more fertile and grow faster than purebreds.


There are several systematic crossbreeding systems. Terminal crossing makes maximum use of both heterosis and breed complementarity. It may utilize two, three, or four breeds, and can be as simple as crossing two purebreeds.


Terminal crossing
In terminal crossing, all of the crossbred offspring are sold and replacement ewe lambs must be purchased or produced in the flock by mating a proportion of the flock to rams of the same breed. In a three or four breed terminal crossbreeding system, crossbred ewes and crossbred rams can be utilized in the system to maximize heterosis.

Rotational crossing
Rotational crossing will also maintain high levels of heterosis. Rotational crossing involves alternating the use of rams of two, three, or more breeds. Ewes are mated to rams of the breed which they are least related. It works best when breeds which function acceptably as both ram and ewe breeds, are utilized.

Roto-terminal crossing
Roto-terminal crossing involves both terminal crossing to produce market lambs and rotational crossing to produce ewe lambs. The best ewes in the flock would comprise the nucleus flock. They would be used to produce replacement ewes. The rest of the ewes in the flock would be bred to a terminal sire to produce market lambs.

Grading up
Grading up denotes the repeated crossing of ewes and their female progeny to rams of a single breed, with the ultimate objective of creating a flock that is indistinguishable from purebred flocks of the ram breed. It is used when only rams of the breed of interest are available or affordable.

Composite breeds
Crossbreeding is also used to form new or "composite" breeds. Once the crossbred base population has been formed, the flock is managed as a purebred flock. This is how many new breeds are created.

Many of the aforementioned crossbreeding systems are difficult to accomplish in a small flock, which may only have the option of one or two breeding groups. The purchase of replacement females would enable the use of a terminal crossing program. Alternating the use of ram and ewe breeds would maintain maternal and growth characteristics in the flock.

Source: http://www.sheep101.info/201/breedingsystems.html

Well, i think that the lamp leg Mary used should be big enough to kill her husband. So i think it should be 42 inch tall and weigh about 11 pounds.
The following is the nutrients of the lamp leg:

Leg of Lamb Canaries Total Fats Saturated Cholesterol Protein
(grams) Fats(g) (milligrams) (g)
(Roasted) 162 6.6 2.4 76 24


Here's a recipe I would suggest Mary cook for the sergeant and his men:
Lamb koftas with a cucumber and mint yogurt

Ingredients

140g/5oz minced lamb
small bunch coriander, chopped
1 tsp cumin seeds
1 tsp coriander seeds, crushed
1 tsp chilli, chopped
1 tsp turmeric
pinch dried cinnamon
salt and freshly ground black pepper
1 tbsp pine nuts
1 lime, zest and juice only
For the yoghurt sauce
110g/4oz yoghurt
½ cucumber, grated and squeezed to remove water
small bunch fresh mint, chopped
1 lemon, juice and zest only
To serve
fresh coriander, chopped
Method

1. Preheat the oven to 220C/425F/Gas 7.
2. Mix all dry ingredients together and toast in a dry pan. Crush in a pestle and mortar. Mix the lamb, the lime zest and juice and all the toasted ingredients together. Form on to wooden skewers and put aside to rest.
3. If the mixture is loose add a little flour.
4. For the yoghurt sauce, miix the yoghurt ingredients togetherin a bowl and set aside.
5. Heat an ovenproof griddle pan until smoking and add the koftas. Griddle on all sides to achieve brown char marks, then transfer to the oven to cook for ten minutes, or until completely cooked through.
6. Serve on a plate with chopped coriander sprinkled over the top and some of the yoghurt mixture.

Source:http://www.bbc.co.uk/food/recipes/database/lambkoftaswithacucum_70013.shtml

3 comments:

Jack Tan said...

I have a funny feeling that the text is all copy and pasted here. But anyway, you stated your source and the information was quite useful. Thanks for putting it up on your blog!

Anuradha said...

Well good job so far but you have not managed to inspire others to comment on your blog neither have you taken the effort to comment on you fellow students' blogs.

Anuradha said...

No comments on your blog and none by you on others blogs. Put in some effort William!!!!!