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Estimates of Heritability of Fly Susceptibility in Dairy Cattle1
TECHNICAL NOTES REFERENCES (1) AMBO, K., Am) U ~ . z u , M. Studies on the Nutritional Significance of the Portal Blood in Ruminants. I. On the Measurement of Blood Flow of Hepatic Vein and Portal Vein by Means of Hepatic Vein Catheter. Tohoku J. Agr. Research, 11: 209. 1960. (2) A~Nlso>r, E. F., HII~I~, ]~. J., Am) LE~rlS, D. Studies on the Portal Blood of Sheep. Biochem. J., 66: 592. 1957. (3) BBNSADOU~,A. Direct Determination of the Absorption of Volatile F a t t y Acids from the Gastrointestinal Tract of Ruminants. P a r t I. Short Chain Volatile F a t t y Acid Analysis in Biological l~aterials. Ph.D. thesis, CornelI University, Ithaca, N. Y. 1960. (4) CONX~AD,H. R., S~IT~, H. R., VA~,~SALL, J. H:, POU~-D~.~, W. D., Am) HIBBS, ,]'. W. Estimating Gastro-Splenic Blood Flow and V F A Absorption from the Forestomachs of Calves. J. Dairy Sci., 41: ]094. 1958. (5) DoBso~r, A., Am) PHI~A:PSO~, A. T. The Influence of Contents of the Rumen and of Adrenaline upon Its Blood Supply. J. Physiol., 133: 76. 1956. (~) F~LE~, G. Measurement of Cardiac Output in Anaesthetized Animals by a ThermoDilution Method. Quart. J. Exptl. Physiol., 39: 153. 1954. (7) FE~hEa~, G. The Reliability of the Thermodilution Method for Determination of the Cardiac Output and Blood Flow in the
ESTIMATES
(8)
(9)
(i0)
(11)
(12)
(13) (14)
Central Veins. Quart ft. Exptl. Physiol., 42: 254. 1957. F ~ L ~ , G., A~D H n ~ , K. J. Measurement of Blood Flow and Heat Production in the Splanchnic Region of the Anesthetized Sheep. Quart. J. Exptl. Physiol., 43: 189. 1958. F~ms, G. F., AND CONlqEP~ G. H. Studies on Bovine Portal Blood. II. Blood Flow Determinations with Observations on Hemodilution in the Portal Vein. Am. J. Ve~. Research, 22~: 487. 1961. HFA~IOK, ft. F., ESSEX, H. E., MAIVlV, F. C., AND BLADES, E. J-. The Effect of Digestion on the Blood Flow in Certain Blood Vessels of the Dog. Am. J. Physiol., 108: 621. 1934. SCHAMBYE, P. Experimental Estimation of the Portal Vein Blood Flow in Sheep. I. Examination of an Infused Method and Results from Acute Experiments. Nor& Vet. Med., 7: 961. 1955. SCHA~BY~., P. Experimental Estimation of the Portal Vein Blood Flow in Sheep. 2. Chronic Experiments in Cannulated Sheep Applying Infusion and Injection Methods. l~ord. Vet. Med., 7: 1001. 19155. S~'ZWART, G. N. The Output of the Heart in Dogs. Am. J. Physiol., 57: 27. 1921. WALDEm'V, D. E., B~OSSZR, T. H., FI~OST, O. L., A~rS, HAaSC~, J. A. Portal Blood Studies in the Bovine. J. Dairy Sci., 44: 1193. 1961.
OF HERITABILITY OF FLY DAIRY CATTLE 1
The use of chemical materials f o r fly-control purposes is definitely limited by excretion of insecticides or their breakdown products in milk, change in the resistance of insects to insecticides, and the short period of activity of repellents. Therefore, new approaches to fly control should -be considered, along with improvement of methods in present use. Several investigators [Pearson, Wilson, and Richardson (3), Pearson (4), and F r y e r et al. ( 1 ) ] , working with fly repellent and insecticides on dairy cattle, have concluded that differences among cows were a p r i m a r y reason f o r variations of fly susceptibility in their results. D a t a f r o m tests at the Oklahoma E x p e r i m e n t Station suggested that these differences might be heritable. Therefore, a study was made in which the resemblances in fly susceptibility between dairy cows of known relationships were measured, thus estimating heritabilities. SOURCE OF DATA The data available for study were counts of the house fly, Musca domestica Linn., the stable 1A portion of these data were reported by G. A. Mount in a thesis presented to the Graduate School, Oklahoma State University, in partial fulfillment of the requirements for the M.S. degree (1960).
543
SUSCEPTIBILITY
IN
fly, Stomoxys calcitrans (Linn.), and the horn fly, Haematobia irritans (Linn.), taken on lactating cows during 1953, 1954, 1957, 1958, 1959, and 1960. The number of counts varied f r o m nine to 32 within different breeds and years. Yearly average counts were used as a measure of normal fly susceptibility of individual cows. Breeds represented were Ayrshire, Guernsey, Holstein, and Jersey. Counts of the three fly species were made on the whole body area of the cow, excluding the head and udder. These counts were recorded f o r an entire breed within a 1-hr period, thus tending to eliminate large variations due to fluctuating fly p o p u l a t i o n levels. Counts were taken under a wide r a n g e of environmental conditions; therefore, each individual cow's p e r f o r m a n c e was measured in different environments. Two hundred and five p a t e r n a l half-sibs representing 23 sires, and 89 dam-daughter pairs representing 25 sires, were obtained f r o m pedigrees of cows for which fly count data were available. To take advantage of larger numbers, heritability estimates were made for combined as well as the individual breeds. Al~ALYSIS OF DATA Heritabilities were obtained by two methods. One was the p a t e r n a l half-sib method in which
544
JOURNAL OF DAIRY SCIENCE
the intra-class correlation coefficient described by Snedeeor (6) was multiplied by four. The intra-class correlation was computed as the ratio of the variance between sires to the total variance. The analysis of variance was a hierarchical classification design programmed for high-speed computation by Pulley (5). The individual breed studies were on an intra-year, intra-sire basis, whereas the combined studies were on an intra-breed, intra-year, intra-sire basis. The second method of estimating heritability was the intra-sire correlation of daughter with dam introduced by Lush (2). The number of dam-daughter pairs counted within the same year was too small to permit an appropriate intra-year analysis. Therefore, an effort was made to estimate correlations due to yearly differences in fly population levels and other en~ironmental peculiarities of years by computing the correlation of unrelated herd mates. The number of unrelated herd mates used per year eo.rresponded to the number of dam-daughter pairs. A reciprocal square root transformation (w
+1 a10 )
intr°duced s x bv Fryer / et X at" (1)
used in an attempt to normalize the fly count data. The formula for heritability was as follows : Heritahility = 2(r~ -- r~) where : r~ : correlation coefficient of dam-daughter pairs r~ -- correlation coefficient of unrelated pairs. RESULTS
Results from the paternal half-sib method were inconclusive and are not presented here. This is probably due to sampling errors which would be magnified by the multiplication by four to express genetic relationship. Additional data and more efficient statistical procedures will perhaps yield more realistic values. Heritability estinmtes of house fly susceptibility (Table 1) were positive in all breeds except Jerseys. These estimates suggest inherited differences in the Ayrshire, Guernsey, and Holstein breeds. Three of the four breeds also produced large heritability values in regard to stable fly susceptibility. I n contrast to the other two fly species, the heritabilities obtained for horn fly susceptibility are negative in three of the four breeds.
EFFECT
TABLE 1 Dam-daughter heritability estimates of fly susceptibility Breed
No. of pairs
House fly
Stable fly
Horn fly
Ayrshire Guernsey Holstein Jersey Combined
25 17 38 9 87
0.10 0.28 0.80 --0.34 0.3,6
--0.36 1.26 0.42 1.62 --0.02
0.32 --1.04 --0.4~8 --0.18 0.14
DISCUSSIOlq
The results of the intra-sire correlation of daughter with dam are probably more reliable than those of the paternal half-sib, because of the larger genie value and type of analysis used. Nine of the 15 heritabilities suggest that perhaps some progress could be made in selection of fly susceptibility on a fly count basis. G. A. MOUNT D. E. HOWELL E. R. ]~EROUSEK 2 AND
R. D. MOR•ISON Departments of Entomology, Dairying, and Statistics Laboratory Oklahoma State University Stillwater, Oklahoma 2Present address: Animal and Dairy Science Department, University of Rhode Island, Kingston, Rhode Island. REFERENCES
(I) FRYER, H. C., SHAW, A. 0., ATKENSON,
F. W.,
S~ITH, R. C., AN]) BOI~A~¢I% A. I~. Techniques for Conducting Fly-Repellency Tests o11 Cattle. J. Econ. Entomol., 36: 33. 1943. (2) LUSH, J. L. Intra-sire Correlation or Regression of Offspring on Dam as a Method of
(3)
(4) (5)
(6)
Estimating Heritability of Characteristics. Proc. Am. Soc. Animal Production, 1940: 293. 1940. PF~SON, A. M., Wmso~.', J. L., A~v~)RIC~.~XDSON, C. H. Some Methods Used in Testing Cattle Fly Sprays. J. Econ. Entomol., 26: 269. 1933. PE:U'CSON, A. M. A~ Improved Method for the Determination of Cattle Fly Spray Repellence. J. Econ. Entomol., 28: 160. 1935. PULLL'Y, P. E. A Program for the Analysis of Variance of J=[icrarchical Classification Design. M.S. thesis, Oklahoma State University, Stillwater, Oklahoma. 1959. S,WKDECOa, G. W. Statistical M~thods. 4th ed. The Collegiate Press Inc., Ames, Iowa. 1946.
O F Z I N C B A C I T R A C I N ON S I L A G E M I C R O O R G A N I S M S
A variety of compounds has been added to fresh forage plants at ensiling, in attempts to control microorganisms. Some of the additives were designed to depress total bacterial activity and others to favor the acid-producing organisms. The purpose is to protect against
putrefaction and loss of nutrients, which inevitably occur when spore-forming anaerobes become competitive. Marked inhibtion or retardation of these organisms has been only partially successful and the merits of the many preservatives now available are much disputed.
ESTIMATES
(8)
(9)
(i0)
(11)
(12)
(13) (14)
Central Veins. Quart ft. Exptl. Physiol., 42: 254. 1957. F ~ L ~ , G., A~D H n ~ , K. J. Measurement of Blood Flow and Heat Production in the Splanchnic Region of the Anesthetized Sheep. Quart. J. Exptl. Physiol., 43: 189. 1958. F~ms, G. F., AND CONlqEP~ G. H. Studies on Bovine Portal Blood. II. Blood Flow Determinations with Observations on Hemodilution in the Portal Vein. Am. J. Ve~. Research, 22~: 487. 1961. HFA~IOK, ft. F., ESSEX, H. E., MAIVlV, F. C., AND BLADES, E. J-. The Effect of Digestion on the Blood Flow in Certain Blood Vessels of the Dog. Am. J. Physiol., 108: 621. 1934. SCHAMBYE, P. Experimental Estimation of the Portal Vein Blood Flow in Sheep. I. Examination of an Infused Method and Results from Acute Experiments. Nor& Vet. Med., 7: 961. 1955. SCHA~BY~., P. Experimental Estimation of the Portal Vein Blood Flow in Sheep. 2. Chronic Experiments in Cannulated Sheep Applying Infusion and Injection Methods. l~ord. Vet. Med., 7: 1001. 19155. S~'ZWART, G. N. The Output of the Heart in Dogs. Am. J. Physiol., 57: 27. 1921. WALDEm'V, D. E., B~OSSZR, T. H., FI~OST, O. L., A~rS, HAaSC~, J. A. Portal Blood Studies in the Bovine. J. Dairy Sci., 44: 1193. 1961.
OF HERITABILITY OF FLY DAIRY CATTLE 1
The use of chemical materials f o r fly-control purposes is definitely limited by excretion of insecticides or their breakdown products in milk, change in the resistance of insects to insecticides, and the short period of activity of repellents. Therefore, new approaches to fly control should -be considered, along with improvement of methods in present use. Several investigators [Pearson, Wilson, and Richardson (3), Pearson (4), and F r y e r et al. ( 1 ) ] , working with fly repellent and insecticides on dairy cattle, have concluded that differences among cows were a p r i m a r y reason f o r variations of fly susceptibility in their results. D a t a f r o m tests at the Oklahoma E x p e r i m e n t Station suggested that these differences might be heritable. Therefore, a study was made in which the resemblances in fly susceptibility between dairy cows of known relationships were measured, thus estimating heritabilities. SOURCE OF DATA The data available for study were counts of the house fly, Musca domestica Linn., the stable 1A portion of these data were reported by G. A. Mount in a thesis presented to the Graduate School, Oklahoma State University, in partial fulfillment of the requirements for the M.S. degree (1960).
543
SUSCEPTIBILITY
IN
fly, Stomoxys calcitrans (Linn.), and the horn fly, Haematobia irritans (Linn.), taken on lactating cows during 1953, 1954, 1957, 1958, 1959, and 1960. The number of counts varied f r o m nine to 32 within different breeds and years. Yearly average counts were used as a measure of normal fly susceptibility of individual cows. Breeds represented were Ayrshire, Guernsey, Holstein, and Jersey. Counts of the three fly species were made on the whole body area of the cow, excluding the head and udder. These counts were recorded f o r an entire breed within a 1-hr period, thus tending to eliminate large variations due to fluctuating fly p o p u l a t i o n levels. Counts were taken under a wide r a n g e of environmental conditions; therefore, each individual cow's p e r f o r m a n c e was measured in different environments. Two hundred and five p a t e r n a l half-sibs representing 23 sires, and 89 dam-daughter pairs representing 25 sires, were obtained f r o m pedigrees of cows for which fly count data were available. To take advantage of larger numbers, heritability estimates were made for combined as well as the individual breeds. Al~ALYSIS OF DATA Heritabilities were obtained by two methods. One was the p a t e r n a l half-sib method in which
544
JOURNAL OF DAIRY SCIENCE
the intra-class correlation coefficient described by Snedeeor (6) was multiplied by four. The intra-class correlation was computed as the ratio of the variance between sires to the total variance. The analysis of variance was a hierarchical classification design programmed for high-speed computation by Pulley (5). The individual breed studies were on an intra-year, intra-sire basis, whereas the combined studies were on an intra-breed, intra-year, intra-sire basis. The second method of estimating heritability was the intra-sire correlation of daughter with dam introduced by Lush (2). The number of dam-daughter pairs counted within the same year was too small to permit an appropriate intra-year analysis. Therefore, an effort was made to estimate correlations due to yearly differences in fly population levels and other en~ironmental peculiarities of years by computing the correlation of unrelated herd mates. The number of unrelated herd mates used per year eo.rresponded to the number of dam-daughter pairs. A reciprocal square root transformation (w
+1 a10 )
intr°duced s x bv Fryer / et X at" (1)
used in an attempt to normalize the fly count data. The formula for heritability was as follows : Heritahility = 2(r~ -- r~) where : r~ : correlation coefficient of dam-daughter pairs r~ -- correlation coefficient of unrelated pairs. RESULTS
Results from the paternal half-sib method were inconclusive and are not presented here. This is probably due to sampling errors which would be magnified by the multiplication by four to express genetic relationship. Additional data and more efficient statistical procedures will perhaps yield more realistic values. Heritability estinmtes of house fly susceptibility (Table 1) were positive in all breeds except Jerseys. These estimates suggest inherited differences in the Ayrshire, Guernsey, and Holstein breeds. Three of the four breeds also produced large heritability values in regard to stable fly susceptibility. I n contrast to the other two fly species, the heritabilities obtained for horn fly susceptibility are negative in three of the four breeds.
EFFECT
TABLE 1 Dam-daughter heritability estimates of fly susceptibility Breed
No. of pairs
House fly
Stable fly
Horn fly
Ayrshire Guernsey Holstein Jersey Combined
25 17 38 9 87
0.10 0.28 0.80 --0.34 0.3,6
--0.36 1.26 0.42 1.62 --0.02
0.32 --1.04 --0.4~8 --0.18 0.14
DISCUSSIOlq
The results of the intra-sire correlation of daughter with dam are probably more reliable than those of the paternal half-sib, because of the larger genie value and type of analysis used. Nine of the 15 heritabilities suggest that perhaps some progress could be made in selection of fly susceptibility on a fly count basis. G. A. MOUNT D. E. HOWELL E. R. ]~EROUSEK 2 AND
R. D. MOR•ISON Departments of Entomology, Dairying, and Statistics Laboratory Oklahoma State University Stillwater, Oklahoma 2Present address: Animal and Dairy Science Department, University of Rhode Island, Kingston, Rhode Island. REFERENCES
(I) FRYER, H. C., SHAW, A. 0., ATKENSON,
F. W.,
S~ITH, R. C., AN]) BOI~A~¢I% A. I~. Techniques for Conducting Fly-Repellency Tests o11 Cattle. J. Econ. Entomol., 36: 33. 1943. (2) LUSH, J. L. Intra-sire Correlation or Regression of Offspring on Dam as a Method of
(3)
(4) (5)
(6)
Estimating Heritability of Characteristics. Proc. Am. Soc. Animal Production, 1940: 293. 1940. PF~SON, A. M., Wmso~.', J. L., A~v~)RIC~.~XDSON, C. H. Some Methods Used in Testing Cattle Fly Sprays. J. Econ. Entomol., 26: 269. 1933. PE:U'CSON, A. M. A~ Improved Method for the Determination of Cattle Fly Spray Repellence. J. Econ. Entomol., 28: 160. 1935. PULLL'Y, P. E. A Program for the Analysis of Variance of J=[icrarchical Classification Design. M.S. thesis, Oklahoma State University, Stillwater, Oklahoma. 1959. S,WKDECOa, G. W. Statistical M~thods. 4th ed. The Collegiate Press Inc., Ames, Iowa. 1946.
O F Z I N C B A C I T R A C I N ON S I L A G E M I C R O O R G A N I S M S
A variety of compounds has been added to fresh forage plants at ensiling, in attempts to control microorganisms. Some of the additives were designed to depress total bacterial activity and others to favor the acid-producing organisms. The purpose is to protect against
putrefaction and loss of nutrients, which inevitably occur when spore-forming anaerobes become competitive. Marked inhibtion or retardation of these organisms has been only partially successful and the merits of the many preservatives now available are much disputed.