Department of Animal Science Florida Agricultural
Mimeograph Series No. AN68-2 Experiment Station
July, 1967 Gainesville, Florida
SOW PRODUCTIVITY AS INFLUENCED BY SEASON
(A SUMMARY OF FIVE YEARS' DATA)
H. D. Wallace, M. E. Demaree and'G. E. Combs1/
A report in 1962 (1) summarized sow performance in the-University of Florida
sow herd over a two-year period, as influenced by season. Results indicated that
performance was better during the cooler:moAths, when measured in terms of number
of pigs per litter, weaning weights and conception rates. The present report sum-
marizes reproductive performance of the University herd for the ensuing five-year
The sow herd consists of 2 breed groups purebred Durocs and Duroc x Landrace
Fl crossbreds. Approximately 12 purebred Durocs and 50 crossbreds are maintained in
The Duroc sows are bred either to Duroc boars to furnish replacements for the
Duroc herd, or to Landrace boars to furnish replacements for the crossbred herd.
The crossbred sows are bred to Hampshire boars. Pigs from this 3-way cross consti-
tute the main source of pigs for feeding experiments.
Definite breeding groups have not been formed and held constant, but, rather,
are formed at each breeding period depending on the animals available. The objective
has been to expose about 25 sows at each breeding period. The breeding season cov-
ers a 21-day period and is spaced every two months so as to provide .a total of six
farrowings per year.
Hand mating is practiced exclusively. Sows are mated either once or twice dur-
ing the heat period. Data on the comparison of one vs. two matings has been the
subject of a previous report (2).
Feeding and Management of Sows During Gestation
All sows are maintained on forage during gestation. In the months of November,
December and January, forage is not usually abundant; however, good forage is gen-
erally available during the remainder of the year.
Sows are hand-fed once per day in groups of 8-10 animals. The level of concen-
trates fed depends on forage conditions, condition of the sows, and stage of gesta-
1/ Wallace, Animal Nutritionist; Demaree, Research Assistant; and Combs, Animal
Nutritionist, Animal Science Department.
A flushing procedure is followed in which the concentrate level is increased
50 percent 10 days prior to breeding and throughout the breeding period. After the
sows are settled, the feeding level is reduced to 3-5 lb. per head per day. Thirty
days prior to farrowing the level is raised to 5-6 lb. per head per day. Also, com-
mencing 30 days prior to farrowing, Hygromycin is added to the gestation ration to
help eliminate worm infestation to the young pigs. This treatment is continued dur-
ing the lactation period.
The gestation ration is described in Table 1.
Table 1. Composition of rations fed sows during gestation
Ground yellow cotn 61.19 65.09
Ground whole oats 20.00 10.00
Soybean meal (50% protein) 14.30 20.30
Steamed bonemeal 1.00 1.00
Ground limestone 0.75 0.75
Iodized salt 0.50 0.50
Trace mineral supplement1- 0.06 0.06
B-vitamin supplements 0.10 0.20
Vitamin B12 supplement/ 0.10 0.10
Vitamin A and D supplement- 2.00 2.00
1 Calcium Carbonate Co. swine mix. Adds the following to the ration (ppm):
Manganese (35.5), Iron (43.8), copper (3.0), cobalt (1.0), zinc (50.4) and
2 Contains 2,000 mg. riboflavin, 4,000 mg. pantothenic acid, 9,000 mg. niacin
and 10,000 mg. choline chloride per pound of supplement.
3 Contains a minimum of 9 mg. B12 per pound of supplement.
4 Contains 14 gm. vitamin A supplement (10,000 IU.gm.), 4 gm. vitamin D supple-
ment (9,000 IU/gm.) and 890 gm. yellow corn.
5 The gestation ration contains approximately 16 percent crude protein and the
lactation ration contains approximately 18 percent crude protein.
Feeding and Management of the Sows at Farrowing and During Lactation
The pregnant sows are moved to the farrowing barn on the 110th day of gesta-
tion, where each is thoroughly cleaned with soap and water and sprayed with benzene
hexachloride to remove lice.
All sows are fed twice per day while in the farrowing barn, being driven froni
the farrowing stalls or pens to the individual feeding stalls located in the adjoin-
ing wing. Prior to,farrowing, each sow is fed 3 lb. of concentrates each morning:
and evening. On the day of farrow feed is offered only if the sow appears hungry.
The next day 3-4 lb. of feed is offered. This amount is increased each day, so that
by the end of the first week of lactation most sows are consuming 8-9 lb. feed per
day. This feed level is maintained during the second week, at the end of which the
pigs are weaned.
The 'lactation ration is also described in Table 1.
Care and Management of Litters
On the day of birth pigs are weighed and ear-notched for identification. Navel
cords are tied off if necessary, and the navel treated with a tincture of iodine.
Needle teeth are carefully clipped.
Injectable iron is administered to all pigs between 3 and 5 days of age, and
male pigs are castrated at one week of age.
Heat lamps are used as needed to provide warmth for the baby pigs. Pens are
cleaned each morning. A special effort is made to provide a dry environment for
the pigs at all times. Wood shavings serve as bedding. Automatic drinking cups
provide fresh water for the sows and litters.
Results and Discussion
A summary of all farrowings is presented in Table 2. The relationship of sea-
son to pig losses during the first two weeks of lactation is presented graphically
in Figure 1.
A total of 503 litters was farrowed, with an average of 11.17 live pigs per
litter. The average birth weight for all pigs farrowed was 2.96 pounds. An aver-
age of 9.39 pigs was weaned per litter at two weeks of age, giving an average sur-
vival rate of 84.06%. The average two-week weight of the 4723 pigs weaned was 7.31
Of the 26 farrowings, only one (October, 1965) was a failure. Several sows in
this group aborted their litters prior to entering the farrowing barn. Except for
three sows, the ones that farrowed had small litters. Negative tests for Brucellosis
and Leptospirosis were obtained. The cause of poor performance was not determined.
As one would expect, the seasonal influences are not expressed as clear, uni-
form patterns. A careful examination of the data shows that early spring farrowings
(February through April) have generally been the most successful. This has been re-
flected in higher survival rates and heavier weaning weights. Sows farrowing at this
period have an environmental temperature advantage at breeding, during gestation, and
during lactation. The most difficult period to farrow, without the benefit of temp-
erature-controlled buildings, is during the period from June through October. Lit-
ter size has been satisfactory during this period, but pig survival has averaged low-
er. Sows are restless, and do not take care of their pigs as well during these hot
Table 2. Seasonal farrowing performance of University of Florida sow herd
August 1962 March 1967
Date Number Live pigs Av. birth Av. no. pigs Av. weaning Percent
of litters per wt. per weaned weight survival
farrow farrowed litter pig lb. per litter (2 weeks) birth to
July: 1964: :
WEIGHTED MEANS 503 (Total) 11.17 2.96 9.39 7.31 84.06
-Figure 1. Influence of Season on Productfivity
(University of Florida Sow Herd)
l Losses from
Ej Number pigs
birth to weaning
weaned per litter
nA 1. r-'--- --
. cL.. Dec. reD.
1962 1962 1962 1963
Aug. Nov. Jan.
1963 1963 1964
Season of Farrow
Mar. May July
1964 1964 1964
Figure 1 (Continued). Influence of Season on Productivity
(University of Florida Sow Herd)
Losses from birth to weaning
13.0 I Number pigs weaned per litter
E 8.0 .
Mar. May Aug. Oct. Jan. Mar. June Aug. Oct. Jan. Mar.
1965 1965 1965 1965 1966 1966 1966 1966 1966 1967 1967
Season of Farrow
For the five-year period, pig losses during the first two weeks of lactation
have averaged 16 percent. The greatest losses occurred in August 1965, when 31 per-
cent of the live pigs born did not survive. Baby pig scours were a serious problem
during this farrowing.
A compilation of the University of Florida sow herd performance during the past
five years is presented. The data emphasize that the period of greatest stress comes
during the warm summer months of June through October. However, a year-around mul-
tiple farrowing program has proven quite feasible, even though a sophisticated en-
vironmental control system has not been used in the program.
1. Wallace, H. D. and G. E. Combs. 1962. Sow productivity as influenced by sea-
son (A summary of two years' data). Fla. Animal Sci. Mimeo. Series No. 63-2.
2. Wallace, H. D. and G. E. Combs. 1962. Sow productivity as affected by single
vs. double matings. Fla. Animal Sci. Mimeo. Series No. 63-4.