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The University of Western Australia
Cesar Rosales Nieto School of Animal Biology and The UWA Institute of Agriculture, Faculty of Science
Cesar completed a Bachelor degree Plant and Animal Science with first class Honours at the University of San Luis Potosi in his home country of Mexico. He then worked at Mexico’s National Institute of Forest, Agricultural and Livestock Research as a researcher. In 2004 he went to the United States and completed a Master degree in Animal Science, with an emphasis on the physiology of reproduction, at Texas A&M University. In 2009, a scholarship from the Mexican National Council for Science and Technology enabled Cesar to come to UWA to undertake his PhD, examining the effect s of muscle and fat accumulation on the reproductive performance of female sheep. Cesar plans to submit his thesis later this year and will return to Mexico to help advance agriculture in in his home country with the knowledge gained at UWA.
THE UWA INSTITUTE OF AGRICULTURE Postgraduate Showcase 2013: Frontiers in Agriculture
Advancing puberty in female sheep: its all about muscle and fat
Cesar Rosales Nieto Graeme Martin
Andrew Thompson
Team Supervisors
Acknowledgements:
Mate ewes as lambs
Economics (more lambs on the ground)
Increase lambs weaned
Increase in lifetime performance
Increased rate of genetic gain
Reproductive efficiency
The Australian sheep industry
Puberty
Internal factors External factors
Gonadotrophins LH – Luteinizing Hormone
FSH – Follicle-Stimulating Hormone
Ovulation Egg
Ovary
Physiological sexual maturity has
been reached
Liveweight (50 – 70%)
Age is a secondary factor
(-) (+)
Fat tissue (Body Condition / Live weight)
Leptin concentration
(-)
(+)
Leptin concentration
Puberty/Fertility
Reproduction Fat
(-) (+)
Rate of muscle accumulation
(-)
(+)
Fecundity Follistatin
Reproduction Muscle
Hypothesis
Puberty ‘switch’
Leptin Adipose tissue
Body Composition
Ovulatory signal
Ovulation
Higher values for growth and muscle and fat accumulation are also more able to successfully reproduce at younger ages
This reproductive success is positive related to circulating
concentration of follistatin and leptin
Follistatin Muscle tissue accumulation
The “Adipose theory”
2009 - 2011
Experiment
Medina (n = 136)
Pingelly (n = 190)
Katanning (n = 514) Sire: Wide range in genetic values (ASBV) for growth,
muscle and fat
Live weight was recorded (LWC) Fat and muscle scan at post-weaning
Depth of Eye Muscle (EMD)
Depth of Fat (FAT)
Genetic value for weight (PWT)
Genetic value for muscle (PEMD)
Genetic value for fat (PFAT)
Material and Methods Animals and treatments
Puberty Period (5 to 8 months old)
Vasectomized rams
Harness with a crayon
Fertility Period (8 to 10 months old)
Entire Rams
Pregnancy scan (60 days)
Fertility rate
Material and Methods Animals and treatments
• Mixed Model for age at first oestrus, puberty and fertility.
• Covariates: EMD, FAT, PEMD, PFAT, PWT
• Fixed Effects: BTRT (Birth type - Rear type) and Dam age
• Random effect: Ewe lamb sire
Material and Methods Data analyses
20
25
30
35
40
45
50
Live weight (Kg)
Results
Puberty Period Fertility Period
LWC
≥ 200; 75%
≤ 50; 35%
Experiment
Age at first oestrus (Days)
200
210
220
230
240
0 1 2 3 4 5 6 7 8 9 PWT (Kg)
40
60
80
100
0 1 2 3 4 5 6 7 8 9
Puberty (%)
PWT (Kg)
2 3 4 5 6 7
FAT 40
60
80
100
15 18 21 24 27 30 33
EMD
Muscle accumulation (EMD; mm)
Pube
rty
(%)
Fat accumulation (FAT; mm) Results Puberty and muscle and fat accumulation
0
20
40
60
80
100
30 35 40 45 50 55
Fertility (%)
Live weight at start of Mating (Kg)
0
20
40
60
80
100
15 18 21 24 27 30 33
EMD FAT
2 3 4 5 6 7 Fat accumulation (FAT; mm)
Muscle accumulation (EMD; mm)
Fert
ility
(%)
20
40
60
80
100
1 3 5 7 9
Follistatin
Follistatin (ng/mL)
Fert
ility
(%)
0.8 1.2 1.6 2 2.4 2.8 3.2
Leptin
Leptin (ng/mL) Results Fertility and hormonal control
1
1.4
1.8
2.2
Leptin
Leptin (ng/mL)
2
3
4
5
15 20 25 30 35 Follistatin
Total follistatin (ng/mL)
Muscle accumulation (mm)
Conclusion
Puberty ‘switch’
Leptin Adipose tissue
Body Composition
Ovulatory signal
Ovulation
Muscle tissue Follistatin X Intramuscular
fat
Live weight Growth