Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Effect of breed type and post-weaning plane of nutrition on age at puberty and pregnancy rate in beef heifers
J. Heslin 1,2, D.A. Kenny 1, A.K. Kelly 2 and M. McGee 1 1Teagasc, AGRIC, Grange, Dunsany, Co. Meath, Ireland; 2School of Agriculture and Food Science,
University College Dublin, Belfield, Dublin 4, Ireland.
Introduction Approx. 1 m suckler cows in Ireland
• 85% spring-calving
Currently late-maturing (LM) continental breeds dominate breeding within suckler herd Source of replacement heifers ~25% dairy herd, ~75% suckler herd
• Within-herd generation of replacements “Replacement Index”
• Dairy expansion – opportunity for sourcing
2
Introduction Reproductive efficiency is essential for
profitability • Calve at 24 months
• Seasonal calving herds e.g. spring/autumn
» Central to this is age at puberty – available for breeding
Modelling analysis from Grange: Delaying age at first calving from 24 to 36 months decreased net margin per ha by 50%
Teagasc Presentation Footer 3
Calving at 24 months of age Current reproductive performance of
beef heifers in Ireland • Average age @ first calving is 31.5 months
• 20% calve for first time between 22-26 months
• Top 15% of herds: 50% of heifers 1st calve at 24 months
Challenging but can be done i.e. The Derrypatrick, Newford and Maternal Herds
Teagasc Presentation Footer 4
Objectives 1. Establish age at puberty for contrasting
replacement heifer breed types
2. Study the effect of overwinter plane of nutrition on age at puberty and pregnancy rate in beef heifers
3. Identify growth rates and develop nutritional regimes to reach target weights to maximise reproductive performance
Teagasc Presentation Footer 5
Experiment details Duration 2 years (2015, 2016)
Animals 320 heifers (160 annually) Spring-born Early – (Angus; EM) OR late – maturing
(Limousin; LM) sire breeds Born to either suckler beef (B) OR dairy
(D) cows Sourced via ICBF – known parentage
Teagasc Presentation Footer 6
Animal management Indoor “winter” period
Housing Housed slatted-floor shed; pens of 5 141 (2015) and 150 (2016) days until
turnout to pasture (Nov-Apr)
Diet Grass silage (69% DMD) to appetite +
1.5kg barley-based concentrate/head/d (MOD) Grass silage (69% DMD) and concentrate
to appetite (HI)
Teagasc Presentation Footer 7
Teagasc Presentation Footer 8
Animal management Outdoor “grazing” period
Turnout to pasture April 7 (2015), April 15 (2016) 6 groups Diet Rotationally grazed perennial ryegrass
dominant swards Breeding Late April – Late July in both year
simulate spring – calving system A.I. – single sire – AM:PM rule
Animal measurements Dry matter intake Silage + conc (pen basis)
Bodyweight Indoor period – weekly Outdoor period – fortnightly until “in-calf”
Blood sampling Twice weekly – [Progesterone] to determine
age at puberty
Scanning Pregnancy confirmation
Teagasc Presentation Footer 9
Feed (DM) intake of heifers during indoor period
Teagasc Presentation Footer 11
No difference in daily silage, concentrate or total DM intake between D and B heifers EM heifers had a higher DM intake of concentrate and GS than LM heifers By design, heifers on HI diet had a higher DM intake of concentrates and total DM
intake than heifers on MOD diet, while MOD heifers had a higher total DM intake of silage
0
1
2
3
4
5
6
7
D B
Dam Breed (DB)
kg D
MI/h
d/d
ConcentrateGrass silageTotal
0
1
2
3
4
5
6
7
EM LM
Sire Breed (SB)
kg D
MI/h
d/d
ConcentrateGrass silageTotal
0
1
2
3
4
5
6
7
8
MOD HI
Nutrition (N)
kg D
MI/h
d/d
ConcentrateGrass silageTotal
***
Teagasc Presentation Footer 12
0.84
0.70 0.78 0.76
0.51
1.03
D B EM LM MOD HI
Dam breed (DB) Sire breed (SB) Nutrition (N)
ADG Indoor Period (kg) *** ***
Teagasc Presentation Footer 13
05
101520253035404550556065707580859095
100
D B
Dam breed
%
6 w sub6 w preg12 w preg
05
101520253035404550556065707580859095
100
EM LM
Sire breed
%
6 w sub6 w preg12 w preg
05
101520253035404550556065707580859095
100
MOD HI
Nutrition
%
6 w sub6 w preg12 w preg
Heifer reproductive performance
Compared to B heifers, D heifers had a: Greater 6 week submission rate Higher 6 and 12 week pregnancy rate
Compared to LM heifers, EM heifers:
Were younger at puberty Had a higher 6 week pregnancy rate However, there was no difference in 12 week pregnancy rate
Compared to MOD heifers, HI heifers were: Younger at puberty However, there was no difference in 6- or 12- week pregnancy rate
Conclusion Heifers from dairy dams had a higher
pregnancy rate at 6 and 12 weeks Early maturing sired heifers had a
higher 6 week pregnancy rate than late maturing heifers. No difference in 12 week pregnancy rate No difference in pregnancy rate
between MOD and HI heifers
Teagasc Presentation Footer 14
Target weight at breeding and required performance
EM Dairy LM Dairy EM Beef LM Beef Target WT @ breeding, kg 360 380 420 450
Housing WT, kg 200 210 290 300
Winter ADG required, kg 0.87 0.95 0.65 0.80
Teagasc Presentation Footer 16
1 135 d winter
2 6 weeks turnout and breeding assuming ADG 1kg
3 Breeding 1st May
Target weight – Breed type LM Dairy
Housing WT 210kg Target WT @ breeding 380kg 120 d winter (Nov-Mar) ADG required 0.82kg ADG (Mar – May) 1.20kg 150 d winter (Nov-Apr) ADG required 0.89kg ADG (Apr-May) 1.20kg
Teagasc Presentation Footer 18
Target weight @ breeding: 380kg
Target weight – Breed type EM Suckler
Housing WT 290kg Target WT @ breeding 420kg 120 d winter (Nov-Mar) ADG required 0.48kg ADG (Mar – May) 1.20kg 150 d winter (Nov-Apr) ADG required 0.63kg ADG (Apr-May) 1.20kg
Teagasc Presentation Footer 19
Target weight @ breeding: 420kg
Target weight – Breed type LM Suckler
Housing WT 300kg Target WT @ breeding 450kg 120 d winter (Nov-Mar) ADG required 0.65kg ADG (Mar – May) 1.20kg 150 d winter (Nov-Apr) ADG required 0.76kg ADG (Apr-May) 1.20kg
Teagasc Presentation Footer 20
Target weight @ breeding: 450kg
Implications at farm level
Teagasc Presentation Footer 21
EM D LM D
Age at puberty, d 420 438
6 week preg % 72 56
8 week preg % 83 71
10 week preg % 91 78
12 week preg % 94 95
Key weights (kg) Time EM D LM D
Housing 220 213 Yearling 314 308 Turnout 338 336 Puberty 341 353
Breeding 332 328 1st AI 354 358
Conception 362 369
Implications at farm level
Teagasc Presentation Footer 22
EM B LM B
Age at puberty, d 426 437
6 week preg % 58 54
8 week preg % 70 69
10 week preg % 75 79
12 week preg % 82 82
Key weights (kg) Time EM B LM B
Housing 280 311 Yearling 360 384 Turnout 385 403 Puberty 390 415
Breeding 377 397 1st AI 403 420
Conception 415 429
Implications at farm level
Teagasc Presentation Footer 23
ADG Indoor Period EM D 1 EM D 2 0.59 kg 1.07 kg
Pregnancy rate EM D 1 EM D 2
6 week 70 % 74 %
8 week 78 % 89 %
10 week 90 % 92 %
12 week 95 % 92 %
Time EM D MOD EM D HI
Housing 219 kg 221kg
Time EM D MOD EM D HI
Turnout 304 kg 372 kg
Time EM D MOD EM D HI
Breeding 305 kg 358 kg
Implications at farm level
Teagasc Presentation Footer 24
Time LM D MOD LM D HI
Housing 213kg 214kg
Time LM D MOD LM D HI Turnout 299kg 373kg
Time LM D MOD LM D HI Breeding 301kg 356kg
ADG Indoor Period LM D 1 LM D 2 0.59kg 1.13kg
Pregnancy rate LM D 1 LM D 2
6 week 61% 54%
8 week 74% 72%
10 week 74% 85%
12 week 92% 92%
Implications at farm level
Teagasc Presentation Footer 25
Time EM B MOD EM B HI Housing 281kg 279kg
Time EM B MOD EM B HI Turnout 350kg 421kg Time EM B MOD EM B HI
Breeding 348kg 406kg
ADG Indoor Period EM B MOD EM B HI
0.46kg 1.02kg
Pregnancy rate EM B MOD EM B HI
6 week 57% 60%
8 week 70% 70%
10 week 73% 78%
12 week 78% 85%
Implications at farm level
Teagasc Presentation Footer 26
Time LM B MOD LM B HI Housing 310kg 312kg
Time LM B MOD LM B HI Turnout 372kg 435kg
Time LM B MOD LM B HI Breeding 373kg 421kg
ADG Indoor Period LM B MOD LM B HI
0.43kg 0.89kg
Pregnancy rate LM B MOD LM B HI
6 week 55% 54%
8 week 75% 62%
10 week 85% 72%
12 week 90% 74%
Results - Breed type
Teagasc Presentation Footer 27
Time EM D LM D EM B LM B Housing 220 213 280 311*** Yearling 314 308 360 384* Turnout 338 336 385 403 Puberty 341 353 390 415*
Breeding 332 328 377 397 1st AI 354 358 403 420
Conception 362 369 415 429
Weight (kg) - Breed type
Teagasc Presentation Footer 28
Time EM D LM D Housing 220 213 Yearling 314 308 Turnout 338 336 Puberty 341 353
Breeding 332 328 1st AI 354 358
Conception 362 369
Time EM B LM B Housing 280 311 Yearling 360 384 Turnout 385 403 Puberty 390 415
Breeding 377 397 1st AI 403 420
Conception 415 429
Teagasc Presentation Footer 29
200
250
300
350
400
450
(kg)
Time-point
Bodyweight gain from housing to conception
AA D LM D AA S LM S
Turn-out to pasture
Teagasc Presentation Footer 30
050100150200250300350400450
410
415
420
425
430
435
440
AA D LM D AA B LM B
(kg)
(day
s)
Age at puberty Weight at puberty
Age and bodyweight at puberty – Breed type
Teagasc Presentation Footer 31
0102030405060708090
100
6 week preg 8 week preg 10 week preg 12 week preg
%
Pregnancy rate - Breed type
AA D LM D AA B LM B