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FACTORS AFFECTING LACTATION FEED INTAKE OF THE SOW
Dr.
Brian Hardy
NutriVision Inc.
Background
Genetic improvement has produced a breeding female that is very prolific, has a high milk yield capability, is later maturing, has more lean and less fat in the body, and generally has a lower feed intake in lactation. The main reasons for high culling rates and poor sow longevity are the inability of the sow to maintain a satisfactory level of reproductive performance and factors associated with poor foot condition or leg conformation. These situations are observed shortly after weaning and reflect the loss of body tissue during lactation, resulting from inadequate nutrient intake. Maintenance of high energy, amino acid and mineral intakes are critical to keeping the sow in the herd for a long and economically viable reproductive lifetime. The energy and amino acid requirement during lactation depends on parity, the weight of the sow, milk yield and its composition, the number of piglets suckling, lactation length and the change in the body weight and composition of the sow during the lactation period. The parity 1 gilt and some sows do not consume adequate feed intake to meet these nutrient demands. They mobilize their body fat for energy and lean tissue for amino acids to make up for the nutrient deficit in supply from the daily feed intake. They often reach weaning in a catabolic state, which has a negative impact on subsequent reproductive parameters, shown as, elongated wean to estrus interval, less sows bred within 7 days of weaning, lower conception rate, poorer embryo survival and consequently variable farrowing rate and subsequent litter sizes.
Biology
Milk accounts for 75% of the total energy requirement in lactation. Glucose is the most important metabolic nutrient in milk production and 70% of total body glucose is used by the mammary gland. During the first 7 days of lactation, feed intake is frequently too low to meet the demands for energy and consequently body fat reserves are mobilized. These can be used with an efficiency of 88%. The energy requirement on day 1 of lactation is about 10,000-12,000 kcal ME/day, rising to 18,000-20,000 kcal ME/day by day 14-18 of lactation.
The piglet growth rate is dependant on the milk yield and its composition. It takes approximately 4 grams of milk to produce 1 gram of weight gain. The required milk yield is therefore 10 kg/day to achieve a litter weight gain of 2.25 kg/day (10 pigs growing at 250 g/day).
The total lysine requirement is 26 g/day to maintain a litter growth rate of 1kg/day. The litter of 10 pigs requires 58.5 g/day and the sow requires about 2.5 g/day for maintenance, resulting in a need for a daily intake of 61 grams of total lysine per day. Inadequate supply from the dietary intake necessitates mobilization of body protein.
The parity 1 gilt has an additional requirement for lysine to meet the need for maternal growth of lean tissue. Normally this challenge is not satisfied in the first lactation and the loss of body protein is the primary cause for the additional days taken to exhibit estrus after weaning the first litter and sometimes the cause of the lower second litter size. The loss of body protein in the first week after farrowing can account for up to 45% of the total amount mobilized throughout the whole lactation. Encouraging gilts to increase intake quickly after farrowing is crucial when lactation periods are short. A high-energy intake is needed to maximize the utilization of high lysine levels in special gilt lactation diets. Cross fostering to maximize the gilt litter to 10 suckling pigs can be beneficial. Increasing the feed intake in the gilt lactation by 1kg/day (e.g.4.5 kg to 5.5 kg/day) can increase the second litter size by 1 piglet.
The amount of body reserve, both lean protein mass and back fat at the point of farrowing and weaning has a greater impact on overall reproductive performance than the loss of body tissue during the lactation period. It is generally accepted that a sow weighing less than 150 kg at weaning will take up to 5-7 days longer to show estrus than animals of heavier body weight. Sows must be in an anabolic condition to start a new reproductive cycle.
The most negative influences on lactation feed intake are excessive feed intake in gestation resulting in over-conditioned sows at farrowing and also high temperatures in the farrowing room.
Water intake has a large influence on feed intake. Water must never be restricted. In late gestation water intake is in the range 8-12 liters/day. At farrowing this may decline to about 6 liters/day. In lactation this will increase to an average of 14 liters (range 7-20 liters/day). Water flow rate through nipple drinkers should be 0.6-1.0 liters /minute. Water presented in bowls should always be clean.
Factors Affecting Lactation Feed Intake.
There are many factors that can influence feed intake in lactation and some of these are given in the tabulated information.
Factors Affecting Lactation Feed
Intake
|
Factor |
Guidelines |
|
Prefarrow Feed Intake |
High feed intake in the last 2-5 weeks of
gestation has no effect on lactation feed intake. High intake
throughout gestation will result in lower intake in early lactation. |
|
Gestation Feed Intake |
An inverse relationship exists between gestation
and lactation feed intake. Lactation feed intake declines by 1 kg/day
for every ½ kg/day increase in gestation feed over and above 2.25
kg/day. This applies more to sows than gilts. |
|
Environmental Temperature |
Optimum temperature for the sow is 15-24°C
and for newborn piglets 29-35°C.
Lactating sows will reduce their feed intake by 100 g/day for every 1°C
change from 15-24°C and by ½
kg/day for every 1°C change
over 24°C. |
|
Energy Level in Diet |
Lactating sows do not adjust intake based on
dietary energy level. Some adjustment may occur due to fiber level
with reference to gut fill. Generally increasing energy density by
fat addition in the feed will result in higher daily energy intakes. |
Wet v. Dry Feed |
A water: meal ratio of 3:1 will increase feed
intake by 10-15%. Always provide a separate source of clean water. |
|
Pellet v. Meal Form |
Pellets tend to give higher feed intake than dry
meal, but similar intake to wet meal. |
|
Feed Particle Size |
Fine grinding increases digestibility, but may
also increase gastric ulcers. Feed intake in sows may be improved
with a coarser grind. Suggested corn micron size is 800-900 microns. |
|
Light |
Feed Intake increases with light exposure of 16
hours or more. |
|
Humidity |
Pigs cannot sweat and lose heat by convection and
evaporation. Skin must be wet for evaporative cooling. Misting or
water drip systems help. Cooling the sow’s snout helps when room
temperatures are high. |
|
Lactation Weight Loss |
Sows often lose 10-12 kg in a 21-day lactation
with no detriment to subsequent performance. |
|
Stage of Lactation |
Feed intake follows milk production and litter
size. Feed intake at day 1-7 should provide 10,000-16,000 kcal ME/day
(3-5 kg/day). Peak milk yield occurs at 18-21 days and needs
18,000-21,000 kcal ME/day (5.5-6.5 kg/day). |
|
Protein Level |
Intake of 18% protein lactation diets is
unaffected by protein level in the gestation diet. High room
temperatures 25°C will reduce
feed intake more when lactation diet has over 20% protein. |
|
Health Status |
Disruptions to health will reduce feed intake. |
|
Ease of Farrowing Process |
Piglets should be born at approximately 20-30
minute intervals. Any difficulty incurred will cause distress and
lower feed intake. Notable examples are poor uterine muscle
contractions, constipation, high temperature, low water intake, low
blood glucose, mastitis, etc. |
|
Gestation Sow Weight Gain |
Extreme body weight gain in gestation will
increase body weight loss in lactation resulting in lower feed intake
during the suckling period. |
|
Gestation Sow Back fat Gain |
Fat sows eat less food. High fat gain in
gestation is mobilized in lactation reducing feed intake. Sows with
excessive back fat at farrowing (over 25-27 mm) may reduce feed intake
by 2.5-5.0% relative to leaner sows (18-20 mm). |
|
Piglet Processing Time |
Processing piglets on day one
post-farrowing
disturbs the suckling stimulus and the sow/piglet behavior pattern.
This may reduce feed intake in early lactation. |
|
Weaning Age |
The lactation curve provides maximum milk output
at 18-21 days. Weaning earlier than this time will result in lower
feed intake and lower milk output. Sows weaned early have lower
average lactation feed intake. |
|
Floor Type (Comfort Level) |
Systems without bedding may be uncomfortable.
Slatted floors increase air- flow and may chill animals in cold
weather due to drafts. Manure level in the pit will influence this. |
|
Energy Source (Starch/Fat/Fiber) |
Fat addition to diets in hot weather is
beneficial as it reduces metabolic heat output. Always ensure an
antioxidant is included with the fat. Fiber is beneficial for
increasing gut capacity. Starch is quickly degraded to utilizable
glucose. A balance of all energy sources is needed. |
|
Constipation |
Constipation can be due to low feed intake or low
fiber in the diet. Both modify water re-absorption in the gut, and
metabolic stress. An adequate supply of a good water- holding fiber
source, a good water supply and correct mineral balance is essential
to minimize constipation. |
|
Farrowing Room Staff |
Training is critical in both theory and practice
to ensure an understanding and skill level to achieve the objectives
of the farrowing room operation. Give recognition for a job well
done. |
|
Feeding Frequency |
Maximum intake per meal is 2.75-4.0 kg. Feeding
3 or more times per day will help to maximize feed intake. Allocate
more feed during the cooler hours in summer time. |
|
Mold and Mycotoxins |
Molds are unpalatable. Mycotoxins reduce feed
intake and cause reproductive disorders. Fusarium mycotoxins, T2 and
vomitoxin (4-20 ppm) and Fumonisins (20-175 ppm) are extremely toxic.
Zearalenone (1-30 ppm) cause reproductive problems. |
|
Ingredient Palatability |
High levels of minerals (Calcium and Phosphorus)
can be unpalatable. Limit Calcium to 1.0% and Phosphorus to 0.8%.
Limit changes to ingredient inclusions to small increments at a time. |
|
Feed Scale Used |
Sows achieve higher average daily feed intake if
fed to their appetite level. Feed 2.25 kg/sow on day 1, increasing by
½ kg/day up to 7 kg/day by day 10. |
|
Water Accessibility/Drinker Type |
Lactating sows need 25-45 liters of water/day or
4-8 liters/kg feed. (Milk is 80% water). Water is needed to excrete
excess nitrogen, minerals and toxins. Easy access to a clean, readily
available water source is vital to achieving maximum feed intake.
Keep water temperature below 20°C. |
|
Water Flow |
Sows prefer large gulps of water from troughs.
“Conditioned drinking” by giving sows water in the trough 2-3 times
per day, increases water intake. Water flow rate should be 1.5-2.0
liters/minute if nipples are used. Monitoring water intake is a good
management tool. |
|
Water Quality/Hygienic Status |
Dirty or feed contaminated water bowls limits
water intake. High mineral or bacterial/toxin content does the same.
Water systems should be flushed, sanitized and flushed again before
restocking the farrowing room. |
|
Body Size (Parity) |
Variation exists within parity affecting feed
intake. Smaller, thinner animals and Parity 1 gilts may eat up to
15-20% less feed than larger, fatter animals or older parity sows. |
|
Number Piglets Suckling |
Number of pigs suckling affects milk yield. The
effect on feed intake is not linear. General guidelines indicate an
extra sow feed intake of 250-500 grams per day for each additional
piglet in litter size over 8 piglets. |
Conclusion
1. Use a separate gilt lactation diet for parity 1 and thin sows in lactation.
2. Feed frequently to individual sow appetite throughout lactation.
3. Minimize all adverse affects on feed intake.
4. An increase in average feed intake of 1kg/day can improve piglet wean weight by 0.25kg and next litter size by at least 0.5 piglet.
References
Williams I.H (1998) Nutritional effects during lactation and during the interval from weaning to estrus. In “The Lactating Sow”. Ed. MWA Verstegen and PS Moughan. Wageningen University Press. The Netherlands. P. 159-182
Boyd R.D, Touchette K.J, Castro G.C, Johnston M.E, Lee K.U and Han I.K. (2000). Recent advances in amino acid and energy nutrition of the prolific sow – A review. J. Anim. Sci, 13, (11), 1638-1652.
Aherne F.X. (1994). Litter size and sow productivity. In “Advances in pork production”. Vol 5. 1994 Banff Pork Seminar. Ed GR Foxcroft. University of Alberta
Boyd R.D and Kensinger R.S. (1998). Metabolic precursors for milk synthesis. In “The Lactating Sow”. Ed. MWA Verstegen and PS Moughan. Wageningen University Press. The Netherlands. P. 60-93.
ARTICLE CONTRIBUTED TO “ANIMAL TALK” PUBLISHED
BY
NOTTINGHAM NUTRITION INTERNATIONAL. April 2003
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