Experimental acute inorganic boron toxicosis in the goat: effects on serum chemistry and CSF biogenic amines.

Following acute accidental death of 26 cows exposed to boron fertilizer, effects of inorganic boron treatment in goats were studied. Goats were orally dosed with toxic but sublethal amounts of the fertilizer. Multiple hematologic and serum chemistry parameters were assessed, as were cerebrospinal fluid (CSF) neurotransmitters and some of their metabolites. Significant increases in packed cell volume, hemoglobin, inorganic phosphate, creatine phosphokinase, conjugated bilirubin, sodium, glucose, cholesterol, and aspartate transaminase were recorded. The following serum components were significantly decreased after boron dosing: alkaline phosphatase, magnesium, glutamyltransferase and potassium. There was evidence of a stimulatory effect on both serotonergic and dopaminergic neurons as reflected in elevated CSF monoamine metabolites. Aberrations in clinical behavior, including seizure-like activity, also suggested a central nervous system effect of inorganic boron.

Effects of bovine somatotropin on milk yield and composition, body weight, and condition score of Holstein and Jersey cows.

Forty cows (20 Holstein, 20 Jersey) were administered 0, 5, 10, 15, or 20 mg of recombinantly derived bST daily to determine the effect on milk yield, milk composition, body weight, and body condition score. Administration of bST was from 75 +/- 7 d through 305 d postpartum. A total mixed diet of 45% corn silage and 55% of a concentrate mixture (dry basis) was provided for ad libitum intake. Milk yield of Holstein and Jersey cows administered 20 mg of bST increased 25.3 and 22.8%, respectively, over controls. Fat-corrected milk from Holsteins and Jerseys that were administered 20 mg of somatotropin increased 32.2 and 18.7% over controls, but Jersey response was greatest when 15 mg of bST were administered (27.1% over controls). Dry matter intake of the 20 mg bST group was 13.5% greater than DM intake of controls. Apparent efficiency of production increased linearly with increasing somatotropin. There was no significant change in body weight, but body condition score declined linearly with increasing somatotropin. Most milk composition measures were unaffected by somatotropin. Jersey and Holstein milk yield increased quadratically and linearly, respectively, with somatotropin dose.

Inheritance of height and maturity in crosses between pearl millet landraces and inbred Tift 85DB.

Over 300 landraces of pearl millet were collected in Burkina Faso and grown at the Coastal Plain Experiment Station in Tifton/GA. At Tifton, these landraces are predominantly tall and late-maturing. The photoperiod requirements of these landraces hinder evaluation of their performance in the field and their use in breeding programs. A conversion program has been initiated to transfer genes for dwarf stature and early flowering into the tall, late-maturing landraces. The inbred Tift 85DB is being used as a donor of genes for the dwarf and early characteristics, and was crossed to nine randomly selected landraces from Burkina Faso. The parents, F1, F2, and backcrosses to each parent were grown in the field and evaluated for plant height at anthesis and time in days from planting to anthesis. In general, plant height of F1s was taller than the tallest parent, and in all crosses the maturity of F1s was intermediate between the parents. Numbers of loci conferring height varied among crosses, ranging from 0 to 9.6, and averaged 1.6. Estimated numbers of loci conferring maturity ranged from 0 to 12.8 and averaged 3.4. Broad-sense heritability estimates for height and maturity averaged 60.2 and 65.7%, respectively. Corresponding narrow-sense estimates averaged 23.8 and 48.2%. Joint scaling tests revealed that additive-genetic effects were highly significant for both traits, but dominance and epistatic-genetic effects contributed to the inheritance of each trait in some crosses. The low gene numbers, high heritability estimates, and preponderance of additive-genetic effects suggest that selection for these traits should be effective.

Effect of temperature on toxicity of three pyrethroids to horn flies.

Predictive models describing best-fit regression equations for per cent mortality of horn flies as a function of temperature were determined for each of three pyrethroid insecticides (fenvalerate, flucythrinate and permethrin) over the temperature range 20-35 degrees C. Susceptible horn flies, Haematobia irritans (L.), were exposed to c. an LC70 dose of each pyrethroid using a residue-on-glass method. This technique used confined exposure in chambers with temperatures of 20, 25, 30 and 35 degrees C. Within this range, mortality was greatest at 25 degrees C with all three insecticides. Estimated temperature-mortality equations for each pyrethroid revealed different responses of horn flies to each of these insecticides. Horn flies exposed to flucythrinate demonstrated a linear mortality response that varied inversely with temperature. The response to permethrin was described by a quadratic equation, while the response to fenvalerate was best fitted by a cubic equation.

Effects of the sex-linked prenatal lethal gene tortoise (Moto) on reproduction and growth in the mouse.

The sex-linked prenatally lethal gene tortoise (Moto), an animal model for the human disorder known as Menkes' Kinky Hair Syndrome (MKHS), was studied in the mouse (Mus musculus). The genetic effects upon reproductive performance, birth weight, preweaning growth, and mortality were evaluated to characterize the debilitating effects of the disorder. Reproductive performance of mice were evaluated in two mating types (dam X sire), mutant female (To/+) X normal male (+/Y) and normal female (+/+) X normal male (+/Y). Litter size was reduced in the To/+ X +/Y mating type as expected due to the death of To/Y offspring in utero. Adjusted birth weight of To/+ and +/Y offspring were identical, and both were greater (P less than 0.05) than +/+ offspring. Within one day, however, the To/+ littermates were smaller (P less than 0.05) than +/+ and +/Y and remained consistently inferior in growth through day 30. Normal females and normal males were similar (P greater than 0.05) in growth from day 1 through day 21. Thereafter, +/Y mice were consistently heavier (P less than 0.05) than +/+ mice through day 30. The To/+ genotype had the greatest (13.8%) preweaning mortality rate; +/+ and +/Y genotypes were comparable as were overall comparisons between parity 1 and 2. It is apparent from this study that the copper deficiency and lethality occurring in the progeny of mottled mice were primarily the result of the gene actions in the heterozygote animals. Progression of the disorder may be prevented by experimental determination of both the timing and targeting of in utero therapy in mottled mice and MKHS fetuses.

Effects of inbreeding on economic traits of channel catfish.

Inbred channel catfish (Ictalurus punctatus) were produced from two generations of full-sib matings to study the effect of inbreeding on reproduction, growth and survival. A randomly mated control line was propagated from the same base population to be used for the evaluation of the inbred fish. First generation inbred (I1) and control (C1) lines comprised five full-sib families each. Second generation inbred (I2) and control (C2) lines were produced by mating each male catfish from the I1 or C1 line to two females in sequence, one from the I1 and one from the C1 line. The design also produced two reciprocal outcross lines to be compared to their contemporary inbred and control lines. The coefficient of inbreeding for the inbred line increased from 0.25 in generation 1 to 0.375 in generation 2. The inbreeding coefficient was zero for all other lines. The resulting fish were performance tested in two locations, Tifton, Georgia and Auburn, Alabama and no genotype-environment interactions occurred. Results indicated that one generation of inbreeding increased number of days required for eggs to hatch by 21%, but did not significantly influence spawn weight or hatchability score. However, inbred females produced more eggs/kg body weight than control females. Two generations of full-sib mating in Georgia did not depress weight when expressed as a deviation to random controls but was depressed 13-16% when expressed as a deviation to half-sib out-crosses. Second generation inbreds produced in Alabama exhibited a 19% depression for growth rate when compared to either random or half-sib outcross controls. Survival rates at various age intervals was not decreased by inbreeding. The amount of inbreeding depression varied among families and between sexes.

Effect of crossbreeding on genetic improvement of growth and reproduction in pigs.

Nine-year data from 3426 pigs were analyzed to present a retrospective evaluation of purebred, 2-breed crossing, and 3-breed rotational crossbreeding in the sixties and seventies. No significant heterosis effect was observed for litter size and the average number of pigs per litter (10) remained constant as crossbreeding intensified and the management system improved. Parental crossing did not influence sex ratios and no significant deviation from the 50:50 sex ratio occurred throughout the study. Among purebreds, Hampshire pigs were heavier (P less than .05) at birth and weaning than Duroc pigs. Crossbred dams sired by Duroc or Yorkshire boars produced offspring which were comparable in birth and weaning weights, but weighed less (P less than .05) than those sired by Landrace boars. Effect of birth weight on weaning weight of crossbred and purebred pigs was consistently positive whereas litter size influenced weaning weight negatively. Survival of the pigs was not dependent on parental crossing and did not change over the years when crossbreeding intensified. Yearly environmental variation influenced birth weight and weaning weight, but not litter traits. Male pigs were heavier (P less than .01) at birth than females, but the two groups were comparable at weaning.

Effect of breed of sire on growth of gilts and on subsequent reproductive performance.

This study was conducted to determine the effect of breed of sire on performance of crossbred gilts during the growing-finishing period and on subsequent reproductive performance for three consecutive parties. Average daily gain of gilts sired by Yorkshire boars was greater (P less than .05) than average daily gain of gilts sired by Landrace boars. Average daily gain of gilts sired by Duroc boars was between that of Yorkshire and Landrace sired gilts, but was not significantly different from either. Birthweight of Duroc and Landrace-sired pigs was heavier (P less than .05) than that of Yorkshire-sired pigs. Landrace-sired pigs were heavier at weaning (35 days of age) than were Duroc and Yorkshire-sired pigs. Sows sired by Yorkshire boars were heavier (P less than .05) when pigs were weaned, at 110 days of gestation and one day post-farrowing than sows sired by Duroc boars. Weight of Landrace-sired sows was intermediate between Yorkshire and Duroc-sired sows and was not significantly different from either. Survival traits were not affected by breed of sire.

Effect of initial size on subsequent growth and carcass characteristics of divergently selected channel catfish.

Two experiments were conducted simultaneously to determine (1) if fast-growing fingerlings of channel catfish, Ictalurus punctatus, could be identified by simple visual selection of body size and (2) if initial size advantages influenced subsequent growth and carcass traits of divergently selected channel catfish. Exp. 1 included large (L), medium (M), and small (S) fingerling sizes from each of the control (C), selected upward (+) and selected downward (-) lines for body weight. Exp. 2 included all fmgerlings of the same size (25±5 g) from the 3 lines. Catfish from the L size-class, within each full-sib family in each line, were consistently heavier and longer than M and S size-classes throughout the 53-week experimental period. Fingerlings from the M size-class were also superior in growth to those from the S size-class. Catfish from the + line exceeded those from the C and -lines in body weight and total length at the conclusion of Exp. 1 but not in Exp. 2. This was attributed to the selection of equal size fmgerlings in Exp. 2 which may have excluded fingerlings with the best growth potential from the + body weight line. Results of the two experiments combined indicated that one generation of divergent selection has created genetic differences among lines of channel catfish.

Reproductive performance, growth, and survival of selected and wild X selected channel catfish.

Wild (W) and selected (S) strains of channel catfish (Ictalurus punctatus) were crossed to attempt to introduce genes from wild stocks into a domesticated stock without loss of growth or survival performance. W strain broodfish were from the Kaskaskia River in Illinois and had no history of artificial selection. The S strain broodfish had undergone two generations of selection for multiple-traits since 1974 and had become adjusted to tank, cage, and pond culture conditions. Females and males from both strains were paired in individual spawning pens in all possible combinations and the 19 subsequent egg masses were artificially incubated. The 15 S♀XS♂, 6 W♀XS♂ and 9S♀xW♂ crosses produced 10, 3 and 6 egg masses, respectively. None of the 7 W♀XW♂ pairs spawned. The fish density was standardized to two tanks of 500 in each full-sib family at 4 weeks of age and 200 in each at 12 weeks of age. Domesticated and crossbred fish did not differ in spawn characteristics or 4-week body weight but domesticated catfish grew progressively faster than crossbreds and were 55% heavier and 16% longer by 40 weeks of age. No survival differences were observed among the three genetic groups. A 9-week cage test which followed the tank culture also indicated that domesticated fish were superior to crossbreds in body weight, total length, condition factor, and carcass weight. These results indicated that a single WxS cross did not establish improved gene combinations without loss of growth performance.

Caudal fin abnormality and growth and survival of channel catfish.

From 109 egg masses of channel catfish (Ictalurus punctatus) artificially incubated in the summer of 1981, the fry hatched from 6 egg masses showed some forms of tail abnormality. The morphological deviations from normal fish were classified as tailless, partially-tailed, and triple-tailed (three-lobed). Relative frequencies of these phenotypes varied within and among full-sib families. Absence or partial absence of caudal fin was associated with spine structure abnormalities and severe growth depression. Triple-tailed fish were comparable in tank growth to normally-tailed fish but were superior in cage growth. An association between low hatchability scores and caudal fin abnormality was observed which should be taken into consideration in any breeding program. Differences in body pigmentation was associated with differences in growth of tailless and partially-tailed catfish. Normally pigmented tailless were comparable in body weight to partially-tailed fish. Tailless albinos were, however, inferior in body weight and total length to partially-tailed albinos. Normally pigmented fish were consistently superior to abnormally-tailed fish, regardless of skin pigmentation.

A comparison of gain and carcass characteristics of straightbred and crossbred steers.

Post-weaning growth and carcass characteristics of 318 straightbred (139 Angus and 179 Hereford) and 77 crossbred steers (beef X beef, dairy X beef, and 3-way crosses) were compared under three different feeding regimes. Feeding the steers with a high concentrate ration increased the rate of gain and produced carcasses with higher dressing percentages, more fat but less high-priced cuts as compared to rations lower in the amount of concentrate. Crossbred steers were heavier at weaning, gained more in feedlot, and produced heavier carcasses with less fat but larger loin-eye areas and higher proportions of high-priced cuts. When compared to straightbred steers, beef X beef, dairy X beef, and 3-way crosses were significantly heavier at weaning and produced heavier carcasses with larger loin-eye area, less amount of fat and higher proportions of predicted retail yield. However, differences among the three crossbred groups for weaning weight, carcass weight, dressing percentage, fat thickness, and retail yield were not statistically significant.