Page 2 - APN September 2017
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Pig Industry Calendar of Events
SEP 11 - 12 – Australian Pig Veterinarians (APV) annual conference, Fremantle, WA
SEP 12 - 15 – SPACE, Parc-Expo de Rennes, France welcome.aspx
SEP 19 - 22 – Allen D. Leman Swine Conference, Saint Paul, Minnesota US leman-swine-conference
SEP 20 - 22 – Animal Genetics and Disease 2017, Cambridge, UK https:// coursesandconferences.wellcome erences/form1.aspx?e=635
SEP 25 - 27 – PackExpo Las Vegas, Las Vegas, Nevada, US www.
OCT 22 - 24 – Leman China Swine Conference, Nanjing, China www. china-swine-conference
NOV 7 - 9 – Pig Welfare Symposium, Des Moines, Iowa US pig-welfare-symposium
NOV 19 - 22 – Australasian Pig Science Association (Inc) conference, Melbourne, Victoria www.apsa.asn. au
NOV 20 - 22 – International Tropical Agriculture Conference, Brisbane, Queensland www.tropagconference. org
How to supply event details: Send all details to Australian Pork Newspaper, PO Box 387, Cleveland, Qld 4163, call 07 3286 1833 fax: 07 3821 2637, email:
Gilt-edged management in sow herds
THIS month I focus on several recently complet- ed Australian Pork Lim- ited projects that focused on improving the selec- tion and management of gilts to improve sow lon- gevity in our herds.
These projects are deliv- ering interesting insights on various management strategies including the impacts of parameters such as mating age, mat- ing weight, structural in- tegrity and locomotion scores of gilts on their overall performance and longevity in the breeding herd.
High sow turnover, or replacement rate, is an on- going issue in the Austral- ian pig industry.
Optimising the lifetime performance of the sow gives a producer the best chance of optimising profitability.
Premature culling of sows reduces expected lifetime performance and reduces potential profit margins over the genetic cost of the gilt.
Involuntary culling of lower-parity sows has a serious impact on the par- ity profile of the sow herd and potential herd output.
Also, herds with el- evated culling rates at the lower parities have to retain older sows whose productivity may be mar- ginal, further impacting productivity.
Reducing involuntary culling of lower-parity sows will play a signifi- cant part in reducing the cost of production through reduced replacement costs of sows, improved re- productive performance of multiparous sows and superior performance of growing pigs from mul- tiparous dams.
Traditionally, the main reasons for sow culling in- volved poor reproductive performance, lameness and other health issues.
Sows that do not pro- duce many litters before culling add considerable costs to the production system.
Replacement females re- ally only start paying their way at parity 4 (depending on gilt purchase/develop- ment/animal care costs and pig prices).
Until that time, the cost of the gilt development needed together with the generally reduced produc- tivity of a gilt (compared with older sows) means that gilts can be a burden on profitability.
This is because repro- ductive gilts are expensive to buy or breed on farm and their offspring tend to be lighter at birth, grow slower, have higher mor- talities and weigh less at slaughter compared with the offspring of older sows.
Identifying early life- time performance indi- cators
One APL project fo- cused on the development of the replacement gilt from birth up until the time of selection as a way of improving longevity and lifetime performance for sows.
Dr Rebecca Athorn from Rivalea Australia and Dr Kym Bunter from Animal Genetics and Breeding Unit (as part of project APL 2012/2435) investi- gated the importance of early in life parameters, such as pre-weaning growth and development, rather than just weight for age and conformation, on sow longevity.
Gilts were ranked into 10 roughly equal-sized groups to investigate the association between early in life traits and later re- productive outcomes.
Higher growth rates dur- ing lactation (rather than just heavy birth weights) had the most consistent outcome for improving the probability of gilt se- lection and subsequent re- productive success.
Similarly, increasing weaning age also im- proved the probability of a gilt being selected.
Females with lactation growth rates of <125g/ day had a reduced prob- ability of being selected, mated (displaying oestrus) or farrowing if they were selected.
Females with a lactation weight gain of <2.6kg by 21 days or a 21-day wean- ing weight of less than 4kg were also least likely to be selected – no sur- prises here.
Although increasing weaning age and pre- weaning growth im- proved the probability of a weaned breeder female being selected, the pos- sibility of being selected when birth weights, 21- day weights and post- weaning growth were improved above those val- ues stated above was not found.
At selection (at 160-170 days of age), a higher P2 backfat increased the like- lihood of the selected gilt being mated and success- fully farrowing by just over 20 percent.
In terms of longevity, P2 backfat at selection and survival to parity 2 were very strongly linked.
The percentage of sows being culled by parity 2 decreased from 59 percent to 35 percent between the
leanest and fattest average P2 backfat levels.
Weaning age, weight and pre-weaning gain were positively correlated with each other and weight at selection.
However, it was not pos- sible to isolate whether these early growth peri- ods by themselves are im- portant or whether their major importance is their impact on weight at selec- tion.
Season of birth and farm-specific manage- ment practices had a sig- nificant impact on gilt selection, gilt mating, sow longevity and lifetime performance.
More than 90 percent of the variation explained by known factors for out- comes or lifetime per- formance measures was attributable to the season of birth and the breeding site the gilt was managed at after selection.
This suggests that man- agement factors after selection have a greater effect on performance and longevity, despite the common rearing environ- ment of gilts before selec- tion.
In summary, early in life parameters were not strong predictors of subsequent reproductive performance and sow lon- gevity.
However, those recorded at selection, such as P2 backfat, were better indi- cators of subsequent per- formance and longevity. Gilt structural confor- mation and lifetime pro- ductivity
Lameness is as a major contributor to premature removal rates of sows in Australian herds and has significant implications to the welfare of the sows as well as the economic performance of the herd.
Premature sow removal rates due to reasons asso- ciated with lameness and locomotion issues have been estimated at between 9 percent and 26 percent for Australian sow herds; second only to reproduc- tive failure.
This study, led by Dr David Lines at SunPork South (APL 2012/2436), monitored 2000 ma- ternal line replacement gilts from selection at 25-26 weeks of age (av- erage body weight of 116.5±8.85kg) until their fourth parity.
The gilts were also scored at selection for 18 different traits (six body conformation traits, six front limb structural traits and five rear limb struc- tural traits as well as an overall locomotion score) by two independent and trained scorers.
Data was collected on weight and fat depth to parity 4.
The key outcomes in- cluded:
• Sow retention was af- fected by weight at first mating. Gilts in the 111- 160kg weight range had a higher retention to parity 4 than heavy (≥161kg) or light (≤110kg) gilts at first mating.
• Reproductive causes (failure to cycle, early and late pregnancy failure and
fecundity) accounted for 74 percent of all removals. • Lameness accounted for
10 percent of removals. This suggests that lameness and structural conformation in group housed sows may not be as large an issue as previ-
ously thought.
Of those sows removed
due to lameness, 12.6 per- cent of these were attrib- uted to undesirable limb conformation, with the vast majority due to un- desirable conformation of the hind limbs.
• Rear limbs that were turned in or out (7.8 per- cent of removals) was associated with a poorer locomotion score.
• Tucked-under hind- limbs were 229 percent more likely to be removed for lameness than sows with preferred leg angles.
• Locomotion score at selection was the best indicator of premature removal of all the traits assessed.
Structural conformation had no obvious effects on sow performance.
However, it was found that as the hip angle de- creased (flatter/more hori- zontal), the incidence of stillborn pigs increased.
These outcomes sug- gest that much of the pre- mature removal of sows due to lameness and poor conformation prior to par- ity 4 could be prevented through:
• Close attention to the structural confor- mation (particularly the hindlimb) of replacement gilts.
• Inspection of locomo- tion in replacement gilts.
• Good gilt management strategies to ensure that gilts are mated prior to 150kg live weight and have been fed a quality development diet.
Some changes for R&I
Janine Price, who is well known to many of you, will be leaving us in early September.
Janine has been in her role as Manager, Environ- ment in the Research and Innovation division for the past eight years.
She has provided very strong and valued indus- try advocacy, leadership, guidance and technical direction across both the environmental planning and R&D space over this time.
I sincerely thank her for all her contributions and wish her all the very best for the future.
On another note, I am very pleased to announce that Dr Rebecca Athorn from Rivalea Australia has accepted the position of Manager, Production Innovation.
Rebecca will be com- mencing with APL on October 3 and will be based in APL’s Canberra office.
The R&I team looks for- ward to welcoming Re- becca on board.
If you would like to dis- cuss any of these ideas in further detail or would like a copy of these re- ports, please contact me on 0423 056 045 or heath er.channon@australian
by HEATHER CHANNON Acting Research and Innovation General Manager
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Page 2 – Australian Pork Newspaper, September 2017

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