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SMALL STOCK NUTRITION :sheep: - Coggle Diagram
SMALL STOCK NUTRITION :sheep:
Feeding Sheep
Nutrition plays maj role in overall productivity, health & well-being of flock
Feed costs = approx 2/3 total production cost in - NB producers consider nutrition management as 1st priority
Nutrition = defined in terms of E, protein & specific dietary components e.g. vit & min
Nutrient req depends on:
Species
Size (weight)
Sex
Age
Genetics
Stage & level of production
Climate, Enviro & Activity
BCS
6 major categories of nutrient req
E
Fat
Water
Protein
Vits
Min
During grazing season sheep are able to meet nut req from pasture and salt & min supp
Hay provided - forage limited
Grain added to diet @ certain stages of production when addit nut supplementation needed
Growing lambs - pastures of mixed grass & clover, alfalfa & sml grain = excellent nut in grazing season
Greep diet = high E feed & protein supp - NB for winter-born lambs
Source of clean & fresh water provided @ all times
Feeding Ewe Stock
BW doesn't remain constant throughout year - changes w/ stage of production
Incr gradually = early to late gestation
Nut req highest = lactation
Nut req lowest = maintenance
Nut management affects repro performance
Directly - providing essential nut (e.g. glucose, aa's, vits & essential chem elements)
Indirectly - modifying expression of hormonal fxns >> influences
Ovulation
Embryo dev
Fetal growth
Oocyte maturation
Viability & vigour of newborn
Optimum repro performance
Relationship btwn nutrit provision & req for optimum performance = complex
Nutritionally fluctuating enviros
Specific nutr req of diff phases of repro cycle
When & how nutr affects repro
Measure of nutritional adequacy
Provides info of when, what & how much feed to give
@ 3 stages
3 weeks before breeding
Mid-gestation
Weaning
Measure intake & nutrients absorbed (analysis various blood parameters) - little practical application
Live weight & BCS - express nutr accum or loss (mainly of E)
Practically measuring nutri adequacy in animal on farm
Change in live weight
Change in BCS
Subjective
Sites
Condition scores = @ short ribs
Fat scores = @ long ribs
Scores @ 1 or 5 undesirable
Ewes = 2.5 @ weaning >> 3.5 @ lambing
Thin ewes separated & fed addit E to incr BCS
Obese ewes separated & fed lower E diet @ stage of production when BW = acceptable
Problems w/ overweight ewes < Problems w/ underweight ewes
How to measure repro performance
Breeding rate = no. lambs produced / ewe lambing
Measures of repro response
Fertility (ability to breed)
Fecundity (breeding rate)
Ovulation rate = no of ova shed by ovaries in oestrous cycle @ which mating occurs
Litter size = ovulation rate - wastage of ove, embryo & foetal
Wastage of ova, embryo & foetal = no. ova not represented by viable lambs @ parturition
Wastage reduced litter size
where total wastage occurs early enough re-mating & viable preg still poss - size of little may be less than from earlier preg
Where partial wastage of multiples occurs - preg cont but @ lower litter size
Critical phases of repro cycles
Nutrition before mating (flushing)
ovulation rate
embryo survival
= short term E intake = Current E intake
E intake in immediate pre-mating & mating periods
Ovulation rate responds to short-term E intake only w/in specific intermediate range of BCS
Above & below range - specific to certain genotype = condition achieved that matters & there is no additional + / - effect on E intake currently applying
Positive group response to flushing only achieved where ewes have greater appetite drive over mating
Ewes not in such physiological state & which have lower appetite drive - won't respond to flushing (no matter how long its provided)
Inverse relationship btwn intake @ time of mating & BCS @ 4 weeks before mating
leaner ewes were eating 35% more @ mating than those which had been in fat condition
Effect of short-term E nutrition on wastage insuff understood
Incr wastage assoc w/ high levels of nutrition as well as w/ low levels of nutrition before & after mating
Nutrit factors may operate by disturbing critical endocrine patt thats NB to est & maint of preg - esp in early stages
Wastage dep on genotype & on complex interactions w/ variety of stress factors
Nutrition during recovery period
ovulation rate
Recov period = period btwn end of one preg & lactation and start of next cycle
= Medium term E intake
Recov period most NB period in relation to repro performace
During recov period body tissue reserves - utilized during prev preg & lactation are replenished
Live weight & BCS - criteria used to define medium-term E effects
Fluctuation in E intake during annual cycles = accum of loss of E stored in body (body fat)
E intake in given cycle in mature animal
Relationship btwn live weight &/or BCS and repro preformace = +
@ extremes of liveweight / condition there's uncertainty because of addit hormonally-based metab factors present - affects relationship
ovulation rate = component of repro performance which has clearest + relationship w/ liveweight & BCS
wastage of ova not strongly linked w/ liveweight & BCS
wastage = aspect which is subject to interactive effects w/ non-nutritional factors e.g. stress during recov period & during preg
Nutrition @ 6m before ovulation
ovulation rate - through its effect on follicular dev & ovulation of ovarian follicles leaving primordial pool
Nutrition during pre- & post-natal period
age & weight @ first mating
adult repro life
birth weight
= long term E intake
Nutri of ewes from foetal stag throughout growth & dev of animal until sexual & body maturity
Nutri of female during period influ subseq repro performance
affects time or age of onset of first viable oestrus
Affects fertility & fecundity @ first oestrus
Has residual effects on remainder of repro life
NB
Immediate pre- & post natal periods most crucial periods - can result in permanent stunting of ewes
Severe under nourishment of ewes during late preg - depress birth weight @ vigour of lambs
Lambs born as twins likely to be more undernourished & have smaller birth weights than singles
Neg effect of postnatal nutri on repro performance dep on subsequent levels of nutri
No long-term effects of early post-natal nutri on subseq repro performance when removal of restriction has permitted compensatory growth
When restriction severe & long, compensatory growth didn't overcome initial restriction in growth & mature size either because:
Adult high plane of nutri might be inadequate
Low plane of nutrition during rearing produced animals incapable of compensating
Nutrition during first months after mating
embryo survival
Pastures w/ more than 50% clover / other legumes should be avoided during breeding season - can contain estrogenic comps that decr conception rates
most prenatal deaths occur w/in first 25 days after breeding & usually ass w/ poor nutrition
NB not to make dramatic reductions in nutr supps during breeding season
NB
Det nutri preq for critical phases
How nutr adequacy can be measured or predicted practically in animal on farm
ID nutritional critical phases of life & repro cycles
Nutrition from first months after mating to 6w before lambing
Not as crucial
Ewe flock can be maint on permanent pastures sml grain pastures, aftermath crop fields or hay
foetal growth minimal & total feed req of ewe not signif diff from maintenace diet
Nutrition during last 6w of pregnancy
Don't want to overfeed grain during late gestation - lambing difficulty (large lambs)
Rumen capacity may be limited (ewes w/ multiples)
Supp ewes w/ 0.35-0.45kg corn/barley + norm diet - prevents low birth weights, preg toxemia, weak lambs @ birth & low milk production
Dev fetus acquires approx 2/3 of weight
Nutrition of ewes after lambing
E req incr by 30% & protein req incr. by 55%
Failure to supp ewes accordingly = excessive BW loss. low milk prod, mismothering & poor lamb gains
Protein supps esp critical for ewe flocks w/ high % of multiples
Ewes carrying multiples need to eat more
DM
E (TDN)
CP
Ca & P
Ewes w/ multiples need more nutrient-dense diet
Ewe w/ triplets needs 43% more E than ewe w/ single
Unless high quality legume hays are fed - protein supps necess as part of grain portion of diet
Ewes should be sorted into feeding groups based on type of rearing (single, twin, trip, etc.) - make sure grain supps neither over- or under fed
Ram Feeding
Thin rams should receive grain supps as means to incr. BW & condition
Takes 50 days & approx 1.1kg of corn/day + normal diet to move from 102kg > 113kg
Should be evaluated for BCS 6w before breeding
Mature rams not in breeding can be maint on pasture or wintered on good qual hay
Late maturing types of sheep & larger framed = higher mature BW
Forage alone not adequate nutrition for placing rams in proper BCS for breeding season
Free choice source of water, salt & mins available @ all times
Ram mortality - maj cause = poor nutri
BCS = 3.5-4 before beginning of breeding season
Once turned in w/ ewes - spend min time eating
Can lose up to 12% BW during 45 day breeding period
Feeding sheep during drought
Aim
To meet req of late preg & milking ewes
Lambs & weaners need to grow suffic so that they dont suffer permanent checks
To maint weight in dry sheep
Selective feeding type & amts of feeds to give sheep during drought = 5 steps
Calc which available & suitable fodder is cheapest
Calc amt & cost of selected feed
Assess how much can be met fom pasture or crop residues
Assess watemr requirm
Calc total E & prot req of each class of sheep
Monitoring indiv mobs & adj ration up or down
E & Prot Reqs
Prot generally not limiting factor in frought rations that supp adeq E to meet needs
For sheep w/ special req - care needed to ensure protein needs met
Feed E = maj req & normally first limitation during drought
Where stocks receiving suff E from pasture then for dry stock at least prot won't be limiting
Choosing Supp Feed
2 maj minerals (Ca & Na) likely to be needed as addit supps
Ca deficit when diets consist mainly of cereal grain
To prevent this add 2% finely ground agri limestone to cereal grain
Na defic in most grains
Common salt can be added @ 0.5% if needed - often water supplies have suffic salt
Both can be provided in salt lick
& of each can vary but Ca above 30% starts to limit uptake
Vit A & E likely to be deficient as direct result of drought feeding (rare in adults)
Vit A
stored in liver
young sheep experience deficiencies when havent been exposed to green pasture for 6m
Symptoms = night blindness, eye discharges & ill thrift
obtained from green pasture, hay w/ green colour & yellow maize
Vit E
Inter-relationship btwn Vit E & Selenium
Grains & hays = fair to good sources (variation)
Deficiency = symptoms similar to selenium def (still born lambs, older lambs suffering from stiff & silted gait, lameness & ill thrift
Protein content of some feeds
Some feeds have higher [fat] than others
Levels greater than 5% will decr intake
NB when considering alternative feed sources & how much needs to be incorp into ration
Weaners & lactating ewes have higher reqs for prot & may need supps of cereal grain/hay diets w/ prot rich diet
Prot usually adeq for mature dry sheep in commonly avail drought fodders
Unless stock have special need for prot, vits or mins - choose drought feed that provides E @ lowest cost
Rel easy to est fully supplementary ration for particular class & weight of sheep
Hard to est what proportion of ration to feed if stock have access to pasture or stubble
Start w/ 1/3-1/2 full ration & monitor sheep for weight gain or loss then alter
depends on what fodder is being fed, condition of sheep, aims of feeding & how much paddock feed is available
Common E supps us provide enough prot, vits & mins
E most NB req
Feed resources held on farm often most obv but may not necess match feeding targets
Adjustments to Rations
Hay safest for sudden incr. in ration can gradually be replaced by grain if incr has to be sustained
If grain alone is fed then freq of feeding rather than amt offered @ each feed should be incr
In cold condit - E req incr & rations need incr by 20% or more in severe conditions
Check suitability of lowest cost ration in all other aspects
Checklist
Can sheep eat enough to satisfy needs?
Will supp + paddock feed provide adeq roughage
Is there adeq protein?
Whatever aim - NB to remember = continually monitor condition of mob
Amt supp deps on
Present condit of mob
Amt of paddock feed left in paddock
Weather conditions
monitoring condition of sheep in mob & modifying feeding in resp to changes = sure of amount fed
Water quality
Young sheep have difficulty thriving on water supps w/ higher than 5000ppm salt while adult stock can handle up to 10000ppm esp once used to it
Levels above 10000ppm need to be treated w/ caution
Maj water quality prob = high salt levels
If water contains more than 400ppm magnesium salts = risky to use esp for young sheep
Feeding budgets
Help decide whether to keep & feed stock or sell & buy back
Cost of feeding = feed purchase, labour, freight costs, extra storage, handling & likely amt of wastage
Simple feed budget = help to est likely grain req, predic total cost & monthly cash flow req