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Week 11 Forage brassicas 2 Flashcards

1
Q

Forage brassicas are grown as:

A

A supplement and as an alternative to pastures in animal production systems

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2
Q

What can forage brassicas be fed in ?

A

Can be fed in situ in early summer or through winter:
– Produce high quality feed in periods of feed deficit

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3
Q

What are advantages of Forage Brassicas?

A

– Advantages for pasture renovation by reducing weeds, pests, diseases, creating better soil conditions and cleaner seed beds for establishing new pastures

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4
Q

What should you use forage brassicas?

A
  • Periods of feed shortage through the summer, autumn and winter
  • To supplement periods of low pasture quality
  • To finish stock
  • Prior to pasture renewal
  • Renewed interest in the dairy industry in
    Ireland – dry cows and replacement heifers
  • Beef/sheep production application
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5
Q

Whats important when growing forage brassicas?

A

Cross Compliance

  • Protect soils, water ways and the animals
  • Select appropriate fields – ensure no run off, provide run back area and shelter
  • Move stock daily and no machinery in the field
  • Not all animals will take to grazing brassicas, so it is important to watch animals carefully and, where necessary, remove any animal
  • Housing must be available
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6
Q

Whats the seasonal Growth of Brassicas?

A

Slide 8

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7
Q

Whats the cost of production of :
Kale
Rape/stubble turnip
Fodder Beet

A

Kale €218
Rape/stubble turnip €283/182
Fodder Beet €225

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8
Q

List the 5 main Brassica Crops:

A

Kale

Rape

Redstart (hybrid)

Stubble Turnups eg Tyfon

Swedes

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9
Q

How to calculate CP?

A

N x 6.25 = CP

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10
Q

MJ ME/kg DM :

1- Crops
2- Turnips
3- Swedes
4- Kale
5- Rape

A

1- Crops
2- Turnips 13.0
3- Swedes 13.0
4- Kale 12.5
5- Rape 12.0

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11
Q

Digestibility %

1- Crops
2- Turnips
3- Swedes
4- Kale
5- Rape

A

1- Crops
2- Turnips 90%
3- Swedes 90%
4- Kale 80%
5- Rape 85%

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12
Q

Bulb/stem

1- Crops
2- Turnips
3- Swedes
4- Kale
5- Rape

A

1- Crops
2- Turnips 1.5 - 2.5
3- Swedes 1.5 - 2.5
4- Kale Soft 1.9 Hard 1.0
5- Rape

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13
Q

Leaves

1- Crops
2- Turnips
3- Swedes
4- Kale
5- Rape

A

1- Crops
2- Turnips 2.5 - 3.5
3- Swedes 2.5 - 3.5
4- Kale 2.5 - 3.5
5- Rape 3.0

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14
Q

Composition (% of total DM), quality
(MJ ME/kg DM) and its impact on predicted diet ME from different kale types

Intermediate Stem Cultivars

% total DM
1- Leaf
2- Upper stem
3- Upper mid
4- Lower mid
5- Lower

A

% total DM
1- Leaf 44
2- Upper stem 11
3- Upper mid 14
4- Lower mid 15
5- Lower 16

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15
Q

Composition (% of total DM), quality
(MJ ME/kg DM) and its impact on predicted diet ME from different kale types

Giant Type Cultivars

% total DM
1- Leaf
2- Upper stem
3- Upper mid
4- Lower mid
5- Lower

A

1- Leaf 24
2- Upper stem 17
3- Upper mid 19
4- Lower mid 20
5- Lower 20

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16
Q

Whats not advisable when feeding forage brassicas?

A

Brassicas can be fed as 100% of the total diet but not advisable

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17
Q

Brassicas should form no more than ?% of the diet’s DM content,
with the additional fibre source meeting the remaining ?% of their
daily dry matter requirement

A

70%
30%

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18
Q

Milking cows should not have more than ?% of the diet as brassicas

A

33%

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19
Q

➢ Dry cows not have more than ?% of diet as brassica

A

➢ Dry cows not have more than 70% of diet as brassica

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20
Q

in lambs, a high intake of brassica does what?

A

In lambs, a high intake of brassica increases the risk of photosensitivity

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21
Q

In sheep systems brassicas may make-up ?% of the diet

A

90-100%

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22
Q

Effect of winter feed on dry cow performance

At parturition:

Kale

Swedes

Grass in situ

Silage indoors

A

Kale 3.27

Swedes 3.20

Grass in situ 2.85

Silage indoors 3.58

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23
Q

Conclusions of wintering dry cows

What does Grazing forage kale and swedes in situ do?

A

moderately increased BCS during late pregnancy

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24
Q

Is there a difference between treatments in subsequent milk, protein, fat or lactose yields

A

No difference

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25
Cows grazing PRG sward had a higher or lower BCS at parturition and a lower milk fat post partum
Lower
26
Does grazing forage kale and swedes i situ compared to PRG have an effect on fertility?
No treatment effect on fertility – Calving to first service + conception
27
What is redstart? Whats it expected to yield ?
Hybrid brassica between kale and rape * Rapid growth of forage rape + the winter hardiness and digestibility of kale Multiple grazing's 6t DM/ha
28
Redstart ME is it low or high in fibre
10-11 ME (MJ/kg DM) * Low fibre
29
Whats the advice of sowing redstart?
-Sown from may-august -Eirlier sowing before the end of june offer the potential for multiple grazings -Sow at a rate of 3.5-4.0kf/acre -Braccicas have high requirement for N and P
30
fodder beet 1- What sort of root? 2- Whats DM yields? 3- are they good at being digestible? 4- How does lambs preform on them?
* Root crop * High DM yields (>4-6 t from roots, >1-2 t from tops) total 13-20 t DM/ha * Both fodder beet and swedes are very digestible comparable to cereals (80% DMD) Drummonds * Lamb performance particularly with pulped beet supplemented with protein 1.3-1.4kg/wk
31
Whats the cost of fodder beet €/t utilizable DM 2021 €/t utilizable DM 2022
145 199
32
For best lamb growth, summer brassicas need to be:
grazed for >4wks to allow a period of adaption
33
Typical weaned lamb growth rates on summer brassicas Days from introduction g/day: 1-10 10-20 20 onwards
Days from introduction g/day 1-10 0-50 10-20 150-200 20 onwards >300
34
Whats the establishments like of braccia crop?
* They have a High nutrient requirement * Some varieties are more suitable for grazing * Site selection
35
Sowing of braccia plants:
Sowing – Soil test – Spray off old sward – Min–till plus lime – Fine firm seed bed – 10mm deep – Roll – Fertilise as per soil teat, nitrates and Teagasc Green book
36
Brassicas : -Fibre -Sugar
Brassicas are low in fibre and high in sugars – Risk of rumen acidosis – Hay/straw/silage
37
What should you ensure when feeding animals braccias? What is spring cut silage a good supplement for and why ?
Ensure animals are full before offering new breaks * Spring cut silage is a good supplement for swedes to balance for low CP in the bulb – fibre source also important
38
Feeding hay or straw as supplements to brassicas has many advantages:
– Stabilises gut function – Increased winter weight gain – Minimises ANF problem for animals
39
* Functions of fibre:
– Slowing rate of passage of digesta through the rumen and gut – Increased nutrient utilisation and absorption – Saliva secretion – helps stabilise rumen pH – normal microbial function – Dilute concentrations of SMCO, nitrates and glucosinolates
40
What way should you fence braccias ?
have 2 fences up infront of animals
41
Anti-nutritional properties: (2)
SMCO (S-methyl cysteine sulphoxide) Glucosinolates
42
SMCO (S-methyl cysteine sulphoxide) (5)
– High levels cause red water (haemoglobinuria) in ruminants – Results in depressed DMI and anaemia ** – Restrict excess N and S fertiliser – Avoid feeding flowering brassicas – Cu and Se important – low levels exacerbates SMCO effects
43
Glucosinolates (2)
– Are goitrogenic and influence metabolism in the thyroid gland – Managed by supplementation
44
Nitrate poisoning – health risk * Clinical symptoms:
– Cows maybe unable to stand with milk fever symptoms – Respiratory rate increases – Death and abortion
45
Nitrate poisoning – health risk Causes of nitrate accumulation in the plant (3)
– Periods of rapid growth following a period of stress – High use of N fertilisers – > 2% DM unsafe/toxic.... <1% safe to feed
46
Nitrate poisoning – health risk Ways to minimise risk of nitrate poisoning (2)
– Gradual introduction – no longer than 1h/day – Do not offer hungry cows a crop, feed pasture allowance/ fibre source before moving to brassica crop
47
Mineral composition of brassicas fed during the winter * Calcium When should an animal not be fed brassicas? How much Ca in leaf? Whats the cow requiement? What happens if cow is offered access ca? Whats the story of cow fed low Ca?
– Feeding brassicas in the transition around calving period is risky because of Ca metabolism in the cow – Ideally dairy cows should not be fed brassicas in the 3-wk period before calving or 4-5 d after calving – 40 g/kg DM Ca in leaf – high @ 7kg DM/head/day = 280g Ca – Cow requirement <60g/day – If cow is offered excess Ca pre calving – inability to mobilise stored Ca post calving – Balance with low Ca feeds eg. cereal grains, straw, ha
48
Phosphorus – Daily requirement from cow:
= 24g P/day – 2-4 g/kg DM P in leaf...requires intake of 6kg brassica DM/day – Risk of deficiency
49
Mineral composition of brassicas fed during the winter Potassium and magnesium (2)
– Brassicas high concentration of K, low Mg – Risk in last 4 weeks of pregnancy – hypomagnesium and hypocalcaemia in transition cow – supplementation
50
Copper
– Cattle fed brassica diets over a long period susceptible to Cu deficiency, more than sheep
51
Selenium What is it essential for?
– Essential for the production of glutathione peroxidase – Role in preventing red water – Iodine – Pregnant animals on winter brassicas may suffer from primary or secondary iodine deficiency
52
Efficiency of utilisation: 1- ?% utilisation cows need allowance of ?kg/head/d...actual intake ?kg DM/head/d * Allowance: * High leaf: stem cultivars (?%) increase efficiency vs low leaf:stem cultivars (?%) * Sowing rate – lighter may encourage what
* @90% utilisation cows need allowance of 7.7kg/head/d...actual intake 7kg DM/head/d * Allowance: crop yield, break area, SR * High leaf:stem cultivars (50%) increase efficiency vs low leaf:stem cultivars (20%) * Sowing rate – lighter may encourage thicker stems
53
Frequency and timing or break shift: * Shift the break at least when? * Feed out what source in the morning and shift what in late morning/early afternoon? * For lamb finishing systems where summer brassicas are being grazed, what grazing system is better? than set stocking – LWG/ha ?% * LWG/ha is maximised where lambs are offered ?kg DM/head/d, ?% utilisation leaving residues of ? kg Dm/ha
* Shift the break at least 1/day * Feed out fibre source in the morning and shift the break in late morning/early afternoon * For lamb finishing systems where summer brassicas are being grazed, rotational is better than set stocking – LWG/ha 18% * LWG/ha is maximised where lambs are offered 2-2.5kg DM/head/d, 65% utilisation leaving residues of 1500 kg Dm/ha
54
Water DMI: How long does it take animals to adapt to brassicas?
– DMI 11 kg DM/day (7 kg brassica + 4 kg grass silage) requires 19-20 L/cow in addition to water in crop * Adaption to brassicas – Animals can take at least 2 weeks to adjust and then consume max. VFI when adjusting from a full pasture diet to one that contains 50% brassica
55
Whats the aim of gradual adaption ?
– Aim of gradual adaption is to create a microbe population in the rumen that can cope with changes in diet * Shifts in ratio of NSC and CP * Low fibre intake * Mineral imbalances * ANF
56
Practical steps to ensure effective adaption to brassicas: How long should you run animals on the crop ? When should you observe animals ?
Initially allow access to the brassicas for only a short period – Run animals on the crop for 1-2 h/day – Build up to final allowance 1kg/d over 10 d – High fibre complementary forages – Observe for first 1-2 h of grazing for nitrate toxicity and bloating * Do not allow hungry animals on to the crop during the adaption period – Hunger = gorging, particularly if dominant cows in herd – Best practice is to feed supplementary feed first before offering new break – Reduces acidosis, bloat, nitrate poisoning and choking
57
How do you Measuring crop yield in brassicas?
* Quadrat 1m2 * Measure the crop from 5 different areas within the paddock (away from troughs and fences) * Total DM yield (kg/ha) = FW of 5m2 x DM% x 0.02 * DMs difficult in brassicas * Dry for 24h @90°C, cut up sample
58
Expected DM% 1- Kale 2- Hybrid Brassica 3- Turnip 4- Swede
1- 12-15% 2- 12-14% 3- 9-12% 4- 10-12%
59
Kale utilisation calculation :
* Utilisation % = (Pre-grazing DM yield – post grazing DM yield/ Pre-grazing yield) x 100
60
Factors causing poor or variable livestock performance on brassicas are:
* High water content – DMI * Low NDF – fibre source * Anti-nutritional compounds – nitrates, SMCO and glucosinolates * DM allowance – under/over feeding * High plant S levels – interferes with other trace elements, Cu, Se

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