3.5 Feeding GF pigs pt 1 - T3

Question 1

What is the main objective when feeding GF pigs? What decisions have to be made?

Answer 1

Optimize profit
- maximize income over feed cost
- not the same as “least cost diet”
- not the same as maximizing performance

Decisions
- optimize profit per pig?
- optimize profit per pig place?
- maximize performance?

Question 2

What is gain:feed?

Answer 2

How much they gain compared to how much they eat
- better managed = grow more with the same amount of feed

Question 3

How to go from good performance to best performance?

Answer 3

Higher daily gain = less days in barn
- also better carcass index

Question 4

How is carcass index calculated?

Answer 4

With carcass grading grid

Question 5

Carcass wt vs. live wt? Which dietary factor mostly affects dressing percentage?

Answer 5

• viscera wt is what makes the difference btw the two
• fiber bc it causes a thickening of viscera and reduces carcass wt and negatively affects dressing percentage

Question 6

How do producers minimize variation? Would we minimize variation?

Answer 6

• Could minimize variation by selling pigs over a period from 1 room
• Producers are more likely to keep the all-in-all-out system and take the hit for lack of uniformity (in order to prevent disease)

Question 7

How can feed cost be minimized?

Answer 7

Meet requirements
- excess nutrients = waste of resources and money
- insufficient nutrients = reduce performance, extra das in barn, maintenance costs

Knowledge
- actual and potential performance of pigs
- FI
- marginal effects of nutrients on performance

Question 8

Does an incremental intake of lysine result in an incremental increase of growth?

Answer 8

NO! There is a limit

Question 9

What is performance potential vs. actual performance? Can we change performance potential?

Answer 9

• performance potential occurs under ideal conditions to grow and ideal diets; may not be feasible in production
• as a producer cannot change it but genetic companies can

Question 10

What factors affect performance?

Answer 10

1. Genotype, sex
   - lean genotypes
   - gilts > barrows
2. Environment
3. Health status

Question 11

What does an ideal nutrition program match?

Answer 11

Matches nutrient supply for maintenance + growth to actual performance on farm

Question 12

Stress is…

Answer 12

ADDITIVE
- high temperature, high density, re-grouping
- if you add more stressors you get a greater reduction in feed intake

Question 13

What do we commonly use as an indicator of stress in pigs? Why?

Answer 13

Cortisol = stress hormone
- plasma or saliva
- amygdala (stress signalling)
- hypothalamus (activation of hypothalamic pituitary adrenal axis)
- adrenal (cortisol)

Question 14

What does an increase in cortisol do to pigs?

Answer 14

1. Increases blood glucose concentration
2. Decrease insulin sensitivity
3. Acute: lipolysis; chronic: lipogenesis and proteolysis
4. Immunosuppression: inhibition of pro-inflammatory cytokines

Question 15

Diet nutrient concentration

Answer 15

Req of pigs
- g/day or MJ/day

Diet formulation
- %, MJ/kg

Question 16

How can diets be optimize?

Answer 16

1. Need to know feed intake on a daily basis (g/day, MJ/day)
2. Need to know performance (drives requirements)
   - pigs that grow at higher rates have higher requirements

Question 17

Is a diet higher in lysine a better diet?

Answer 17

NO, depend on context

Question 18

What happens if feed intake is underestimated?

Answer 18

• Diet is formulated to contain more AA (more nutrient dense)
• Excess nutrients, but no impact on lean growth
• Wastes $$$

Question 19

What happens if feed intake is overestimated?

Answer 19

• Diet formulated to contain less AA
• Lower nutrient intake = lower lean gain
• Pigs need more days in barn to finish = higher maintenance costs

Question 20

What happens when health status is reduced?

Answer 20

1. Eat less = grow slower
   - lower protein deposition -> lower AA req (g/day)
2. Shift in protein deposition
   - muscle (fast twitch fibers) -> less protein deposition
   - liver, lung and heart -> increased protein syn
   - greater Phe, Tyr, Trp content in liver than muscle
3. Reduced FI -> compensates for lower daily req
   - req (%) of diet not affected
4. Shift in AA req patterns during immune challenge
   - tryp will have higher req

Question 21

How do we change health status?

Answer 21

several ways
- biosecurity
- vaccination
- cleaning and disinfection
- optimizing enviro

Question 22

What data can be used to access performance?

Answer 22

1. Initial wt
2. Mkt wt
3. Growth rate
   - ADG or days to mkt
4. Lean growth rate
   - carcass data or real-time ultrasound
5. Feed intake (or F/G)

Question 23

How is feed intake on the farm measured and utilized?

Answer 23

1. Measure disappearance
   - regular intervals (every wk)
   - based on delivery slip
2. Relate to body wt
   - weigh pigs at regular intervals
3. Establishes growth performance and feed intake curves

Question 24

Feed intake vs disappearance, what is the difference?

Answer 24

Difference is WASTAGE
- hard to compute
- but want a good estimate bc bad data = bad decisions
- Well adjusted feeders will reduce wastage

Question 25

Disregarding wastage leads to wrong estimates for dietary nutrient content. How?

Answer 25

If you have too much wastage, concluding pigs eat more than they are and will reduce nutrient content (or the opposite)

Question 26

How is pig performance commonly determined? What are the results?

Answer 26

• Weigh pigs weekly or bi-weekly
• Determine back fat w an ultrasound
• Mean lean gain (slaughter data) -> protein deposition (used to estimate AA req)

RESULTS: approximate lean growth curve
- req for several stages of growth
- proper formulation based on farm performance

Question 27

What does lean gain tell you?

Answer 27

Lean gain -> protein deposition -> AA requirements
- lean gain = (final lean - initial lean)/ days in barn
- can use real-time ultrasound to estimate lean gain on farm
- need to estimate lean growth to better know what their req are and FI