beef production lec 5 and 6

Question 1

define breeding objective how would you create one

Answer 1

• set genetic direction for breeding herd
  o use selection to achieve
• SMART

Question 2

define SMART

Answer 2

o	Specific 
o	Measurable 
o	Achievable 
o	Realistic 
o	Timely

Question 3

what would you consider when setting the BO

Answer 3

-	Achieving B/O
o	look at market specs
	gives times and weights wanted
•	know what to aim for
o	look at operation limitations
	feed supply
	can nutrition support targets

Question 4

what is the difference between a breeding vision and BO?

Answer 4

• overall/broad idea of what you want to achieve
  o e.g. produce fertile cows
• BO measurable way to achieve the overall breeding vision e.g. produce a calf every 12 months per cow

Question 5

what is a selection criteria

Answer 5

• allows desired traits to be identified and objectively measured
  o e.g. temp, fertility
   +ve of calm cows: less bruising, less dark meat (undesirable) lower pH

Question 6

what are the 5 main selection tools

Answer 6

breedplan
- EBVS
MAS
genomics
live animal assessment
structural assessment

Question 7

what is a structural assessment?

Answer 7

o objectively measure of conformation

o e.g. foot angles, temp score

Question 8

what is a live animal assessment?

Answer 8

o BCS, fat and muscle scoring

o physical data on animal, influenced by enviro

Question 9

what is MAS and when is it used

Answer 9

o for traits hard to access in the live animal
o measure performance from birth
o e.g. marbling, tenderness

Question 10

when can genomics be used for beef cattle?

Answer 10

o more for dairy, beef have all info from birth
o growth area
o better prediction info to combine EBVS
o genetic conditions

Question 11

how can ease of calving be achieved

Answer 11

for heifers, have a low BW without having EBV values below average for 440/600 day weights

Question 12

what are examples of high and low heritable traits

Answer 12

	the ability of a trait to be passed on the next generation
	high
•	carcass related
o	e.g. BW, weight, fat, muscle
	low
•	fertility related 
o	e.g. calving ease, days to calving

Question 13

what would be selected for in a grass fed system?

Answer 13

 greatest weightings
• 600 day weight
• calving ease

Question 14

what would be selected for in a long fed system?

Answer 14

 greatest weighting
• 600 day weight
• intramuscular fat

Question 15

when would a long fed index be used?

Answer 15

o	Long fed index
	more Japanese markets
•	biggest profit drivers
o	marbling
	want high marbling 
o	sale LW
o	saleable meat%

Question 16

where are the biggest profits in long fed systems in comparison to heavy grass fed?

Answer 16

o	Long fed index
	more Japanese markets
•	biggest profit drivers
o	marbling
	want high marbling 
o	sale LW
o	saleable meat%

 greatest profit drivers
• sale LW
• saleable meat %

Question 17

what is a selection index and when can it be used?

Answer 17

o	Economic weighting of EBV’s 
	“$ net profit per cow mated” 
o	Eg. Bull A -index of $60, Bull B – index of $80, joined to 100 cows 
	½ x $20 x 100 
	$1000 
	$1000 better off going for bull B

Question 18

what is accuracy in relation to EBVS

Answer 18

o accuracy
 increased accuracy has increased data
 indication of how reliable EBV is

Question 19

what EBVs measure carcass

Answer 19

o	Carcass
	more positive better 
	eye muscle area
	fat depth
	marbling
	CW

Question 20

what EBVS measure calving/fertility

Answer 20

scrotal score
gestation length
days to calving
calving ease

Question 21

How is scrotal score EBVs used

Answer 21

 scrotal score
• higher SC increased semen production, earlier age to puberty and heifer progeny, favourable to days to calving, (shorter in daughters)

Question 22

what is the advantage of a low EBV for gestation length

Answer 22

 gestation length
• number of days from conception to calving
• shorter = lighter calf, improved calving ease and rebreeding, heavier at weaning (have more days of growth)
• lower better

Question 23

what is the relation of EBVS to days to joining

Answer 23

 days to calving

• re-join earlier, better calving %

Question 24

what are the 3 traits used in the calving ease index

Answer 24

• calving difficulty score, BW and gestation length

cannot compromise on 400/600 day weight though

Question 25

how is MW related to production and EBVS

Answer 25

 MW
• LW at 5 years
• cow feed requirements
o lower MW eat less, lower feed requirements easier to maintain
• cull values
o higher MW cows worth more (paid per kg)

Question 26

what is the importance of 200, 400 and 600 day weights in EBVS?

Answer 26

	200 day growth
•	measure of growth to weaning 
	400 day weight
•	important for selling as yearlings  
	600 day weight 
•	important for breeders and those targeting heavy weight fed markets

Question 27

what is the 200 milk weight in EBVS

Answer 27

• kg of calf LW @200days
• expected difference in calf weight due to maternal affect
• higher the better (if can match increased milk production with nutrition)

Question 28

what is an EBV?

Answer 28

o gives the genetic merit of the animal in comparison to the average
o higher generally better

Question 29

what are the EBV related to weight

Answer 29

BW, milk, 200/400/600 day weight and MW