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-/ Department of Animal Science Florida Agricultural

Research Report AL-1985-8 Experimental Station

October 1985 \ 86 Gainesville, Florida


THE PROOUCTIVITY OF A 51 SLCE' -fE f DA NATIVE FLOCK

COMPARED WITH TWO UNSELECTED FLORIDA NATIVE FLOCKS


P. E. Loggins. T. A. Olson and S. Tumwasorn


The term "Florida Native" is used to identify a type of sheep that has

been developed in Florida primarily through natural selection. The

phenotypic characteristics Include small body frame, light mature weights

refined bone structure, an open face with varied color patterns, and clean

legs and underline with a coarse wool classification and a grade of low

1/4 blood. These sheep have developed genetic traits that are important

to sheep production under climatic conditions such as exist in the

Southeast United States and subtropical areas. An example of such a

genetic trait in the "Florida Native" sheep is the ability to resist a

high exposure rate of internal parasites. The objective of this study was*

to measure the production level of a University flock selected for 25

years without anthelmintic treatment with two flocks from within the state

where anthelmintics were occasionally used.

Experimental Design

The three flocks studied were the selected untreated University flock

(UF) that was originally established from flocks within the state in 1955

and'two additional flocks obtained in 1980 and identified by the source of

the sheep as the Maxcy flock and the Backlinie flock. The Maxcy flock had

been bred to Florida Native rams for many generations and the Backlinie

flock showed limited Hampshire breeding in its genetic makeup.







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Results and Discussion

The greatest differences between the three flocks of Florida Native

sheep were in ewe weights and hemoglobin levels (Table 1). Ewes from the

Backlinie flock were heavier (P<.01) at each of the three seasons:

prebreeding (August), prior to December lambing (November) and following

the 60 day weaning date of their lambs (February). Weights of the UF and

Maxcy ewes were almost identical at each time. Hemoglobin levels of the

UF and Backlinie ewes were similar at each time measured. The hemoglobin

levels of the Maxcy ewes were lower (P<.01) than those of the UF and

Backlinie ewes in both August and February, perhaps indicating a more

severe internal parasite infestation. The normal hemoglobin level of

mature sheep is 12 grams per 100 milliliters of blood.



TABLE 1. EWE WEIGHTS (Kg) AND HEMOGLOBIN LEVELS (gm/100 ML) BY EWE FLOCK



August August November November February February
Ewe flock weight Hb level weight Hb level weight Hb level


UF 39.4 9.3 42.2 10.2 39.7 7.5

Backlinie 47.1 9.5 49.5 10.1 46.7 7.3

Maxcy 39.5 8.2 42.3 9.5 39.7 6.3

Significance
Level *


t P<.10
**e<.01
***P<. 001










Lambs weights and hemoglobin levels by type on an individual lamb

basis are shown in Table 3. Lambs from Maxcy ewes were lighter at birth

(P<.01) than those from UF and Backlinie ewes and those from UF ewes were

lighter (P<.05) at weaning (12.2 kg) than those of Backlinie ewes (13.4

kg). Maxcy ewes weaned lambs whose average weights were intermediate

between those of the UF and Backlinie ewes. Hemoglobin levels at weaning

and 120 days of age as well as 120 day weight did not differ significantly

due to flock background of the lamb. Ewe survival rate was also examined

and did not differ significantly due to flock of origin.



TABLE 3. LAMB WEIGHTS (Kg) AND HEMOGLOBIN LEVELS (gm/100 ML) BY EWE FLOCK


60 day .120 day
Birth Weaning Weaning Postweaning Postweaning
Ewe type weight weight Hb level weight Hb level


UF 2.8 12.2 10.5 20.2 10.5

Backlinie 2.8 13.4 10.1 21.2 10.1

Maxcy 2.4 12.9 10.1 21.3 10.6

Significance
Level ** NS NS NS


*P<.05
**P<.01



Repeatability estimates for lamb traits are shown in Table 4. They

are, In general, small and since repeatability indicates the tendency for

an individual to repeat its'performance and the upper limit on

heritability of these traits, selection based on lamb weights and

hemoglobin levels would not likely be effective under the prevailing

environmental conditions.







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Summary

An experiment was conducted to compare the production level of a

University flock selected for 25 years without anthelmintic treatment with

two flocks from within the state where anthelmintics were occasionally

used. Data collected from three lambing seasons (1982-1984) Include 270

observations for pregnancy rate, 208 for number of lambs per ewe lambing

and 244 for total lambs born. Significant differences in ewe weights,

hemoglobin levels and lamb survival were determined. Differences in ewe

productivity were small and generally not significant. Thus it appears

that the development of internal parasite resistance will not be greatly

affected by the occasional use of anthelmintics in the ewe flock to

improve performance.