Effect of active immunization against growth hormone-releasing factor on growth and onset of puberty in beef heifers.

Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.     

Safety and efficacy of two sustained-release intrareticular selenium supplements and the associated placental and colostral transfer of selenium in beef cattle

One hundred fifty Se-deficient, pregnant, crossbred beef cows were assigned to 1 of 4 treatment groups: group A, Se-deficient control; group B, 1 Se bolus at 0 and 119 days; group C, 1 Se bolus at 0 days; and group D, 2 Se pellets at 0 days. The Se bolus is an osmotic pump designed to release 3 mg of Se/d into the reticulorumen. The Se pellets weight approximately 30 g and contain 10% elemental Se, which is liberated in the reticulorumen. The Se bolus is designed to provide Se supplementation for 120 days and the Se pellets provide supplementation for up to 18 months. Cattle were maintained on Se-deficient pasture or forages prepared from these pastures for the duration of the experiment. Blood samples were collected from cows prior to treatment (time 0) and at 28, 52, 119, and 220 days thereafter and analyzed for blood Se (BSe) concentration. Body weights were recorded at each sampling time. Blood Se concentration of cows from all supplemented groups were significantly (P less than 0.01) higher than control values at all sample dates after treatments began. By the end of the 220-day study, treatment group-B cattle had significantly (P less than 0.01) higher BSe concentrations than any other group. Body weights of treatment groups fluctuated throughout the study, but did not differ (P greater than 0.05) between groups. One cow and 6 calves born to cows during the experimental period died. Necropsy of 5 calves provided no evidence linking these deaths to treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Duration of immunity in foxes vaccinated orally with ERA vaccine in a bait.

Red foxes (Vulpes vulpes) vaccinated orally with the ERA strain of rabies vaccine in a bait were challenged after 83 mo. Ten of 11 foxes that had seroconverted following vaccination resisted challenge with a virulent rabies virus which produced clinical signs of rabies in 6 of 6 unvaccinated foxes. Five of 11 vaccinated animals retained titers of rabies virus neutralizing antibody throughout the period. Although 6 of 11 had no detectable antibody at the time of challenge, 5 of these 6 resisted challenge and had an anamnestic response, as indicated by elevated titers of antibody when measured at day 77 postchallenge. These results show that foxes can be immunized successfully with a single oral dose of ERA vaccine, probably with protection against a lethal rabies challenge, for at least 7 y.     

Field anaesthesia of leatherback sea turtles (Dermochelys coriacea)

Ten nesting leatherback sea turtles on Trinidad were anaesthetised for electroretinogram (ERG) measurements, using ketamine and medetomidine, reversed with atipamezole. They weighed 242 to 324 kg and were given initial doses of 3 to 8 mg/kg ketamine and 30 to 80 microg/kg medetomidine administered into an external jugular vein; six of the turtles received supplementary doses of 2.6 to 3.9 mg/kg ketamine combined with 0 to 39 microg/kg medetomidine. The lower doses were used initially to ensure against overdosage and reduce the chances of residual effects after the turtles returned to the water, but successful ergs called for step-wise dose increases to the required level of anaesthesia. Respiratory rate, heart rate, electrocardiogram, cloacal temperature, and venous blood gases were monitored, and blood was collected for plasma biochemistry. At the end of the erg procedure, atipamezole was administered at 150 to 420 microg/kg (five times the dose of medetomidine), half intramuscularly and half intravascularly. The turtles were monitored and prevented from re-entering the water until their behaviour was normal. No apparent mortalities or serious anaesthetic complications occurred. The observed within-season return nesting rate of the anaesthetised turtles was comparable with that of unanaesthetised turtles.     

The association between plasma levels of acute phase proteins, haptoglobin, alpha-1 acid glycoprotein (AGP), pig-MAP, transthyretin and serum amyloid A (SAA) in Large White and Meishan pigs

During infection, the acute phase response triggers the release of acute phase proteins (APP), alpha-(1) acid glycoprotein (AGP), serum amyloid A (SAA) and Pig-MAP into the circulation, accompanied by a decrease in plasma levels of transthyretin. We quantified the association between these APP in 26 apparently healthy pigs from two breeds, 13 Large White and 13 Meishan (16 male; 10 female). There was a significant correlation between plasma levels of haptoglobin and Pig-MAP (r=0.57; p<0.05), but no significant associations between any of the other APP tested. We also measured the relationship between PigMAP, transthyretin and SAA, and the proportions of peripheral blood mononuclear sub-sets, CD8(+) cells, CD4(+) cells, CD11R1(+) cells, MHC DQ(+) cells, and monocytes. There were correlations between both plasma levels of Pig-MAP and the proportion of monocytes (r=0.55; p<0.05) and plasma levels of transthyretin and the proportion of MHC DQ(+) cells (r=0.40; p<0.01). Breed and sex influenced plasma levels of Pig-MAP but not plasma levels of transthyretin. Overall, these results suggest closer links between the mechanisms that regulate the release haptoglobin, Pig-MAP and monocytes compared to those that regulate the release of AGP, SAA and transthyretin.     

Tartary buckwheat breeding (<Emphasis Type="Italic">Fagopyrum tataricum</Emphasis> L. Gaertn.) through hybridization with its Rice-Tartary type

Tartary buckwheat (Fagopyrum tataricum) is a highly nutritious crop that is widely grown in Asia, but the flour contains a large portion of the hull if it is ground with industrial processing since the hull is very hard to remove as it adheres to the testa layer of the groat. Rice-Tartary, a particular type of Tartary buckwheat, has seeds with a loose hull and the presence of splits on the sides of the seeds that make dehulling easily. The present study reports on the first attempt of crop improvement in Tartary buckwheat breeding through hybridization. Hybrids were obtained by hybridization of crosses between Tartary buckwheat and Rice-Tartary. Additional crosses were made among selected progenies of these crosses. Based on progeny analysis of the F₁, F₂, and F₃, the character of Rice-Tartary, as exhibited as the presence of splits on the sides of the seeds, is controlled by one gene which is homozygous recessive. A Tartary buckwheat breeding program has been conducted for 6 years based on these crosses. Advanced lines with easy dehull and yield potential are at the stage of ready for yield trials. Production of easy dehulling Tartary buckwheat in the future could boost Canada’s domestic and international markets.     

The effect of introgressions of wheat D-genome chromosomes into 'Presto' triticale

Hexaploid triticale (X Triticosecale Wittmack) (2n= 6x= 42, AABBRR) and wheat (Triticum aestivum L.) (2n= 6x= 42, AABBDD) differ in their R and D-genomes. This produces differences in both agronomic and end-use quality characteristics. Our objective was to determine how introgressions of individual chromosomes from the D-genome of wheat affect these characteristics of a winter triticale 'Presto'. We studied the effects of 18 D-genome chromosome substitution lines, 15 sib-lines as controls, and five check cultivars at Lincoln, NE in 1996, using a randomized complete block design with two replications. The experiment was repeated at Lincoln and Mead, NE in 1997 and 1998 with 15 substitution lines that survived the first winter in Lincoln, along with their 12 control sibs and five check cultivars. Few D-genome chromosomes had positive effects. Chromosomes 2D, 4D, and 6D significantly reduced plant height when substituted for 2R, 4B, and 6R, respectively. No grain yield increases were associated with any of the D-genome chromosomes tested, but three substitutions decreased the grain yield. Depending on the allele of the hardness gene present, chromosome 5D increased or decreased kernel hardness when substituted for 5R or 5A, respectively. Introgressions of chromosomes 1D and 6D improved end-use quality characteristics of Presto. These results suggest that apart from beneficial effects of individual loci located on the D-genome chromosomes, no major benefit can be expected from D-genome chromosome substitutions.     

A genetic study of growth characters and yield characters of oilseed rape

Summary Analysis of single plants in parental, F₁ and F₂ populations of three crosses of oilseed rape indicated cytoplasmic effects in F₁ or F₂ generations for most of the observed characters. There was evidence of dominance for early flowering and early maturity. Heterosis was exhibited for yield and yield components. The heritabilities for the characters under study were generally very low.     

Breeding alfalfa cultivars resistant to the alfalfa weevil

A ten-year study consisting of nine field experiments was conducted to evaluate alfalfa (Medicago sativa L.) for resistance to larval feeding by the alfalfa weevil (Hypera postica Gyllenhal). The results were consistent over years and experiments. Only one source of alfalfa germplasm, designated Starnes, showed resistance to larval feeding in the field under natural infestations of the weevil. The cultivars Team, Arc, and Liberty have been developed from this germplasm source. The only effective method of selection for field resistance to the weevil was field selection under natural weevil infestations. Selection was based on low larval feeding on spaced plants. After six generations of such selection the Starnes germplasm showed only one-third as much defoliation as did the check cultivars. The heritability of the weevil resistance was moderately high. Field resistance was transferred to other strains through hybridization; hybrids were intermediate to the resistant and susceptible parents. Resistance was stable.Laboratory and greenhouse efforts to breed alfalfa weevil resistant alfalfa-using such techniques as adult cotyledon-nonpreference tests, adult leaf-feeding tests, larval-growth and survival tests, oviposition-stimulus tests, and oviposition-nonpreference tests-have failed to produce field resistance.Paper No. 5308 of the Journal series of North Carolina Agricultural Experiment Station, Raleigh, N. C., in cooperation wich ARS, USDA. Received 15 June 1977.