Evaluation of larvicides in developing management guidelines for long-term control of pest blackflies (Diptera: Simuliidae) along the Orange River, South Africa.

In 2000 and 2001 Orange River levels were higher than normal: associated serious outbreaks of blackfly had a substantial detrimental impact on the local economy. The poor control was attributed to the suspected development of larval resistance to temephos. A long-term solution to blackfly control, through the identification of a suitable replacement to temephos for use during high flow conditions, was proposed. This study, however, failed to identify or register a suitable larvicide for use during high flow conditions. Although permethrin was highly effective against blackfly larvae, it was rejected because of its detrimental impacts on non-target fauna. Various formulations of locally produced dry Bacillus thuringiensis var. israelensis (B.t.i.) were tested, but these were ineffective against blackflies. The study also confirmed that resistance to temephos has developed among Simulium chutteri in the middle and lower Orange River. The feasibility of "reversing" the resistance to temephos through the use of the synergist piperonyl butoxide (PBO) was investigated, but the results were not favourable. Furthermore, PBO was highly toxic to blackflies and non-target organisms, and was not recommended for further testing. This means that B.t.i. currently remains the only symptomatic measure of treatment currently applied. Although resistance to B.t.i. has not been reported for blackflies elsewhere in South Africa, there is a need to remain vigilant and to implement an operational strategy that minimizes the risks of resistance developing.

Use of impact testing to predict softness, cow preference, and hardening over time of stall bases.

The objective of this study was to assess the softness and durability of commercially available free-stall bases, and to determine the relationship of stall base softness to cow preference. Clegg impact values were recorded at the University of Wisconsin-Madison Arlington Agricultural Research Station on June 19, 2002, and again on July 24, 2003. The Clegg Impact Soil Tester (model 95051, Lafayette Instruments, Lafayette, IN) with a 20-kg hammer was used in this study. The impact of the hammer on the free-stall base results in a digital display based on peak deceleration of the hammer's impact with the free-stall base in tens of gravities (CIV/H). The CIV/H value, as measured by the Clegg Impact hammer, is based on peak deceleration of the 20-kg hammer's impact with the surface, from a height of 30 cm. Clegg impact measures were highly correlated with cow preference measurements. This relationship suggests that Clegg impact measures of compressibility were good indicators for predicting stall-base acceptance. A cork mattress, 4 foam mattresses, 4 rubber mattresses, 4 rubber mats, and a waterbed were evaluated in this study. Foam-based mattresses lost cushioning ability faster than rubber mattresses or rubber mats. Clegg impact values increased over the 13-mo time period for most stall base types, which indicated a tendency of stall bases to harden.

Factors affecting stall use for different freestall bases.

The objective of this study was to compare stall use (stall occupancy and cow position) by barn side for factors affecting stall use. A closed circuit television system recorded stall use four times per day for a 9-mo period starting May 9, 2001. Six factors were analyzed: stall base, distance to water, stall location within stall base section, stall location within barn, inside barn temperature, and length of time cows were exposed to stall bases. Two barn sides with different stocking densities were analyzed: low (66%), with cows milked by robotic milker; and high (100%), with cows milked 2X in parlor. Six stall base types were tested: two mattresses, a waterbed, a rubber mat, concrete, and sand (high side only). The base types were grouped 3 to 7 stalls/section and randomly placed in each row. Cows spent more time in mattress-based stalls, but the highest percentage lying was in sand-based stalls. The following significant stall occupancy percentages were found: sand had the highest percentage of cows lying on the high stocking density side (69%), followed by mattress type 1 (65%) > mattress type 2 (57%) > waterbed (45%) > rubber mat (33%) > concrete (23%). Mattress type 1 had the highest percentage stalls occupied (88%), followed by mattress type 2 (84%) > sand (79%) > soft rubber mat (65%) > waterbed (62%) > concrete (39%). On the low stocking rate side, mattress type 1 had the highest percentage cows lying (45%) and occupied (59.6%), followed by mattress type 2 > waterbed > soft rubber mat > concrete. Cow lying and stalls occupied percentages were highest for stalls 1) not at the end of a section, and 2) on the outside row, and varied by base type for time cows exposed to stalls and inside barn temperature. Lying and occupied percentages were different for different mattress types. The percentage of stalls with cows standing was higher for mat and mattress-based stalls. Results show mattress type 1 and sand to be superior and rubber mats and concrete inferior stall bases.

Investigation of factors affecting voluntary and involuntary culling in expanding dairy herds in Wisconsin using survival analysis.

Trends in the relative risk of voluntary culling of low-producing cows and involuntary culling of high-producing cows were examined in 186 Wisconsin dairy herds that expanded significantly between 1994 and 1998. A Weibull model for survival analysis was applied to data of 72,456 Holstein cows with first calving from 1981 to 2000; this model included a time-independent effect of age at first calving and time-dependent effects of year-season, age-parity, and within herd-year quintile for combined fat + protein yield (by time period). The relative risk of (involuntary) culling of high-producing cows (versus average cows) increased from 0.5 in 1981 to 1989 to 0.68 in 1996 to 2000. Meanwhile, the relative risk of (voluntary) culling of low-producing cows decreased from 4.20 to 2.55 over the same time period. Variables related to facilities, labor, and management were obtained via survey, and the relative risk of culling for high-and low-producing cows after expansion (1996 to 2000) was calculated for different levels of each variable. Herds with fewer cows per employee and a greater percentage of labor supplied by family members tended to have lower risk of involuntary culling of profitable cows. Likewise, high-producing cows in herds with fans, sprinklers, self-locking manger stalls, palpation rails, and maternity pens had a significantly lower risk of culling than cows in herds without such facilities. Herds that used 100% artificial insemination (AI) had lower risk of involuntary culling than non-AI herds or herds with a cleanup bull, but 3x milking and use of a custom heifer grower led to unfavorable trends in involuntary culling. In summary, this study documented the unfavorable trends in voluntary and involuntary culling in expanding herds and quantified the gains producers can expect in cow survival by investing in improvements in facilities, labor, and management.

Feeding behavior, milking behavior, and milk yields of cows milked in a parlor versus an automatic milking system.

This study compared feeding and milking behavior and milk yields for cows housed in the same barn, fed the same ration, but milked with a conventional milking parlor (parlor) or automatic milking system (robot). Behavioral data were videotaped hourly 1 d/mo for 9 mo. Feeding behavior patterns differed and were more variable for parlor cows than for robot cows. Both groups had low feeding rates at night and early morning. Feeding activity increased after milking and feed delivery for parlor cows. Milking and feeding activity in the robot system increased after human intervention at 7 a.m.; feed bunk activity peaked 3 h later and remained relatively constant from 10 a.m. to 8 p.m. Percentages of cows at the feed bunk were significantly greater for robot cows than parlor cows only at 10 a.m. and 9 p.m. Batch milking of parlor cows with free access to feed, vs. sequential milking of robot cows, with restricted movement to feed by a one-way gate system, resulted in higher peak percentages of cows at the bunk for parlor cows. Lower, more consistent percentages of cows eating at one time suggests that less bunk space may be needed for cows in robotic milking systems. Higher percentages of cows were observed in the robot from 8 a.m. to 1 p.m. and again from 3 to 7 p.m. Percentages of cows in the robot holding area were greatest from 8 to 11 a.m. and 3 to 6 p.m. and were lowest from midnight to 6 a.m. Milk production over 39 d in summer for subsets of cows was slightly but significantly higher (26.4 vs. 25.8 +/- 0.2 kg/d) for cows in the robot group. Milking frequency, days in milk, parity, and maximum air temperature for 3 d (-2 d to day of observation) affected milk yield comparisons. Results have implications for design of feeding and handling facilities used with automated milking systems.

Day and night seasonal temperature differences for a naturally ventilated freestall barn with different stocking densities.

Temperature data were collected during three 28-d periods. Cold-season one-side-occupied (CSOO), warm-season two-sides-occupied (WSTO), and cold-season two-sides-occupied (CSTO) were used to determine day and night freestall barn temperature differences between north-side and south-side, east-end and west-end, and inside to outside of a naturally ventilated, curtain sided, noninsulated barn. Five sensors measured temperature every 15 min for 28-d periods beginning November 30, 2000, July 9, 2001, and December 23, 2001. Stocking densities were 90 to 100% for CSOO south-side and 0% for CSOO north-side; 92 to 108% for WSTO south-side and 46 to 74% for WSTO north-side; and 102 to 116% for CSTO south-side and 64 to 86% for CSTO north-side. Mean day temperatures (MDT) and mean night temperatures (MNT) were different for all within barn comparisons. Inside and outside MDT were different for cold-season periods. MDT differences between inside and outside were CSTO (6.27 degrees F) > CSOO (5.64 degrees F) > WSTO (-0.03 degrees F). MNT differences between inside and outside were CSTO (7.14 degrees F) > CSOO (5.76 degrees F) > WSTO (1.32 degrees F). Absence of animals on one side of the barn during cold seasons decreased the average temperature difference between inside and outside approximately 1 degree F (day 0.63 degrees F, night 1.38 degrees F). South-side MDT and MNT were higher than the north-side for CSOO. MDT differences between north-side and south-side were CSOO (-2.71 degrees F) > CSTO (-1.22 degrees F) > WSTO (-0.36 degrees F). MNT differences between north-side and south-side were CSOO (-2.46 degrees F) > CSTO (-1.06 degrees F) > WSTO (-0.49 degrees F). The average temperature difference for the unoccupied side during cold seasons was almost 1.5 degrees F lower throughout the day than the fully stocked side (day 1.49 degrees F, night 1.40 degrees F). Stocking density was thought to be the major cause of differences between north-side and south-side. East-end and west-end mean temperatures were not different across seasons, therefore, future barn-temperature research with barns of similar characteristics may require only one sensor per side.

Producer satisfaction, efficiency, and investment cost factors of different milking systems.

A modernization survey was used to determine producer satisfaction, efficiency, and investment cost measures of different milking systems. The 301 producers included in this study expanded herd size by at least 50% for smaller herds (60 to 100 cows), or 40% for larger herds, (>100 cows) between 1994 and 1998. The milking systems analyzed and compared were stall barn with pipeline, flat barn parlor walk through and back-out, and herringbone or parallel parlor in old barn or new building. Investment costs per cow were higher for pit parlor in new building, $979. Parallel parlors had a higher cost per milking unit, $13,201, and cost per cow, $860, than herringbone, $8944 and $582, respectively. Herringbone parlors were used more hours per day, 10.75, than parallel parlors, 8.84, of similar size. Pit parlors in new buildings were more labor efficient, as measured by cows per worker hour, than stall barns with pipeline or flat parlor or pit parlors in old barns. Herringbone and parallel parlor in new building were similar for cows per hour (82 and 83) and cows per worker hour (41 and 43). Parallel or herringbone parlors in old barns had fewer cows per hour (63 and 58) than parallel or herringbone parlors in new buildings. Survey respondents showed greater satisfaction for time spent milking, physical comfort of milker, and milk quality for parlor types over stall barn with pipeline. Safety of operator satisfaction was higher for pit parlors than flat parlors or stall barn. No difference in satisfaction was observed between parallel and herringbone parlors.

Modeling milk production and labor efficiency in modernized Wisconsin dairy herds.

The 1999 Wisconsin Dairy Modernization Project was conducted to examine variation in milk production and labor efficiency among herds that had recently expanded. Data were obtained from a sample of Wisconsin herds that expanded between 1994 and 1998. Using rolling herd average milk production in 1998 as the dependent variable in the milk production model, milking frequency, bovine somatotropin use, sprinkler use, average linear somatic cell score, average age at first calving, average days dry, and rolling herd average milk production in 1994 predicted 69% of the variation in milk production. Milking three times daily, using bovine somatotropin, using sprinklers to cool cows, and decreasing linear somatic cell score, age at first calving, and days dry were associated with increased milk production. Each of these variables supports previous research from designed experiments with on-farm results. Variation in milk production is determined primarily by differences in management ability and management practices employed by the dairy producer. Using cows per full-time equivalent as the dependent variable in the labor efficiency model, acres per cow, number of people involved in the milking operation, milking system type, herd size, and interactions between milking system types and herd size predicted approximately 43% of the variation in labor efficiency. As expected, labor efficiency increased with larger herd sizes, fewer acres per cow, and fewer people involved in the milking process. Parallel milking parlors were associated with the highest cows per full-time equivalent followed by herringbone parlors, flat barns, and stall barns.

An overview of experiences of Wisconsin dairy farmers who modernized their operations.

Wisconsin dairy producers who modernized their operations between 1994 and 1998 had positive feelings about their expansion experiences, accompanied by increased production and improved profitability and quality of life. The average herd in this survey experienced increased production during the 5-yr period studied. Nearly all producers were satisfied with their expansion experience. The negative effect on milk production normally associated with expansion was minimal for most years and did not exist if all herds were summarized together. Managing labor appeared to be the most daunting challenge facing producers following expansion. Respondents who built all new facilities observed higher production, greater labor efficiency, and satisfaction with measures of profitability and quality of life than respondents who modified facilities or added no new facilities. As herd size increased, milk production, labor efficiency, and satisfaction with herd performance, profitability, and quality of life increased. Producers who built all new facilities spent less time on farm work, more time managing employees, and had less difficulty finding, training, supervising, and keeping farm employees than producers who modified facilities or added new facilities to existing operations. Larger herds were associated with an increased reliance on nonfamily labor. Managing labor appears to be an easier task for managers of larger herds. The most difficult challenges for producers who modernized their operations were with labor management, financing, and loan procurement, construction and cost overruns, and feet and leg health. Difficulties with expansion differed little between expansion types (same type, some new, or all new facilities) or herd sizes.

A comparison of free-stall barns used by modernized Wisconsin dairies.

A primary objective of the Wisconsin Dairy Modernization Survey was to compare features of free-stall barns available to dairy producers. This study used data from a large random sample of expanding dairy farms to determine whether the theoretical benefits of particular free-stall configurations bear out under on-farm conditions. Comparisons were made among herds using free-stall barns as their primary housing for new versus remodeled facilities, barn design, bedding used, feed-delivery design, manure removal strategies, animal restraint, maternity areas, overcrowding, and cooling methods. Producers who made the transition from tie-stall housing to free-stall housing were satisfied with this decision. New free-stall barns provided a more desirable environment for the herds than remodeled free-stall barns, although initial investments were higher. When new free-stall barns were compared, herds with four-row barns had higher production, lower somatic cell count, and higher stocking rates than herds with six-row barns. Respondents were more satisfied with four- and six-row barns than with two- and three-row barns. Respondents felt sand provided some advantages for cow comfort, while satisfaction with bedding cost and manure handling was higher with mattresses. Dairy Herd Improvement data showed no difference in milk production or somatic cell count for producers who chose sand or mattress-based free stalls. Respondents were more satisfied with the use of drive-through feeding than other feed-delivery designs. Most producers chose to use tractor scrapers to remove manure; however, producers who used automated systems were more satisfied with manure management. Few differences were observed when comparing self-locking head gates to palpation rails. Overcrowding did not have any adverse affect on production or user satisfaction with feed intake or cow comfort. Using supplemental cooling appeared to facilitate higher production.

Trisomy 17p10-p12 resulting from a supernumerary marker chromosome derived from chromosome 17: molecular analysis and delineation of the phenotype.

We report a 5-year-old boy with a small de novo marker chromosome derived from the proximal short arm of chromosome 17. His clinical features include hypotonia, global developmental delay, oval face with large nose and prominent ears, and ligamentous laxity of the fingers. Magnetic resonance imaging of the brain demonstrated mildly delayed myelination. G-band chromosome analysis revealed mosaicism for a small marker chromosome in 85% of the peripheral blood cells analyzed. Fluorescence in situ hybridization and microsatellite polymorphism studies showed that the der(17) was of maternal origin and included genetic material from the 17p10-p12 region, but did not contain the PMP22 gene. One breakpoint mapped within the centromere and the second breakpoint mapped adjacent to the Charcot-Marie-Tooth disease type 1A proximal low-copy repeat (CMT1A-REP). We compare the clinical characteristics of our patient with those previously reported to have a duplication involving the proximal short arm region of chromosome 17 to further delineate the phenotype of trisomy 17pl0-p12.

Mutation and deletion of the pseudoautosomal gene SHOX cause Leri-Weill dyschondrosteosis.

Leri-Weill Dyschondrosteosis (LWD; OMIM 127300) is a dominantly inherited skeletal dysplasia characterized by disproportionate short stature with predominantly mesomelic limb shortening. Expression is variable and consistently more severe in females, who frequently display the Madelung deformity of the forearm (shortening and bowing of the radius with dorsal subluxation of the distal ulna). The rare Langer Mesomelic Dysplasia (LD; OMIM 249700), characterized by severe short stature with hypoplasia/aplasia of the ulna and fibula, has been postulated to be the homozygous form of LWD (refs 4-6). In a six-generation pedigree with LWD, we established linkage to the marker DXYS6814 in the pseudoautosomal region (PAR1) of the X and Y chromosomes (Z max=6.28; theta=0). Linkage analysis of three smaller pedigrees increased the lod score to 8.68 (theta=0). We identified submicroscopic PAR1 deletions encompassing the recently described short stature homeobox-containing gene SHOX (refs 7,8) segregating with the LWD phenotype in 5 families. A point mutation leading to a premature stop in exon 4 of SHOX was identified in one LWD family.

Risk of HIV infection from blood transfusion in Montreal.

OBJECTIVES: To determine the incidence (including associated donor characteristics and time trends) of HIV infection among repeat blood donors and to estimate the risk of HIV transmission from blood transfusion in Montreal and in Canada as a whole. DESIGN: Retrospective cohort analysis. SETTING: Montreal Centre Blood Transfusion Service. PARTICIPANTS: People who donated blood at least twice after Nov. 1, 1985, and at least once from Apr. 1, 1989, to Mar. 31, 1993. INTERVENTION: Blood was screened for HIV by enzyme-linked immunosorbent assay and results were confirmed by Western blot analysis. OUTCOME MEASURES: Incidence density (the incidence rate per person-time) of HIV infection among repeat blood donors by sex, age group and region of residence, and incidence density and risk among first-time donors and for Canada as whole. RESULTS: There were 200,196 eligible donors and 432,631 person-years (PY) of observation. From 1989 to 1993, there were 18 HIV seroconversions among repeat donors. The crude incidence density was 3.3 per 100,000 PY (95% confidence interval [CI] 1.8 to 5.4 per 100,000 PY); it was 4.9 per 100,000 PY among men and 0.61 per 100,000 PY among women. Age-specific incidence per 100,000 PY was 2.5 among those 12-29 years of age, 5.1 among those 30-49, 2.9 among those 40-49, and 1.4 among those 50 and older. Based on an estimated mean "window period" (from when a donor's blood is capable of transmitting HIV until detectable antibody appears) of 25 days, the current risk of HIV infection from repeat donors in the window period is estimated at 1 in 440,000. Inclusion of blood units from first-time donors produces an overall risk of 1 in 390,000 (95% CI 1 in 250,000 to 655,000). The estimated risk per blood unit in Canada as a whole is 1 in 913000 (95% CI 1 in 507,000 to 2,050,000). CONCLUSIONS: This "sentinel" population of repeat blood donors is subject to important trends in HIV spread. Therefore, estimating the incidence density of HIV infection in repeat donors provides insight into the epidemiologic characteristics of HIV infection at minimal expense. As a result of measures to improve blood safety, including HIV testing, the incidence of HIV infection among blood donors in Canada is low and the risk of HIV transmission from transfusion is extremely small, although not zero.

Control of pest blackflies (Diptera:Simuliidae) along the Orange River, South Africa: 1990-1995.

The efficacy of Bacillus thuringiensis var. israelensis (B.t.i.) and temephos in controlling the pest blackfly Simulium chutteri Lewis along the middle Orange River between 1990 and 1995, was assessed. Larvicides were applied by helicopter to rapids and riffles between Hopetown and Onseepkans, a river distance of 807 km. Larvicidal efficacy was based on the change in larval abundance at selected sites before and after each treatment. The success of the control programme was assessed independently by local farmers, who ranked adult blackfly annoyance on a 4-point scale. Before treatment, blackfly annoyance showed consistent peaks in spring, and sometimes in autumn, and levels were unacceptably high for between 17 and 36 weeks of the year. After treatment started, blackfly annoyance levels were reduced significantly. The number of annual treatments necessary to reduce blackfly annoyance to acceptable levels was highly variable (3-13), and depended on river conditions, as well as the efficacy and timing of each treatment. During low-flow conditions (< 50 m3/s), applications became increasingly difficult in braided sections of the river, and dosage calculations were inaccurate because of local abstraction and return flows. Both larvicides worked well in winter (water temperature 11-13 degrees C). Control of the spring outbreak can be planned well in advance, with the first treatment starting in mid July. A flexible protocol is required to control outbreaks at other times of the year. We recommended the use of B.t.i. for most applications, with increased dosages during algal blooms (> 1500 cells/ml). The use of temphos in the Orange River should be considered only during algal blooms or when flows exceed 300 m3/s. We conclude that helicopter application of larvicides is an effective method or controlling blackflies, along the middle Orange River.

Angiotensin II formation in dog heart is mediated by different pathways in vivo and in vitro.

Angiotensin-converting enzyme (ACE) inhibitors (I) have beneficial effects that are presumably mediated by decreased angiotensin II (ANG II) production. However, in vitro assays in human heart extracts have demonstrated that > 75% of ANG II-forming enzyme activity was not inhibited by captopril (Cap) and therefore did not appear to be related to ACE but was inhibited by chymostatin, suggesting that it was predominantly chymase-like activity. Previous work in our laboratory has demonstrated a similar relative contribution of ACE and chymase-like activity toward ANG II formation in vitro in dog heart tissue extracts. Accordingly, we compared Cap-inhibitable ANG II formation in vitro in heart tissue of five adult mongrel dogs to the in vivo Cap-inhibitable, ANG II-forming activity across the myocardial bed in four openchest, adult mongrel dogs. In vitro studies demonstrated that only 6 +/- 2% of ANG II formation was inhibited by Cap from heart tissue extracts of the left ventricular midwall. In in vivo studies, ANG I (0.5 nmol/min) followed by ANG I plus the ACE inhibitor Cap (0.1 mumol/min) was infused into the left anterior descending artery, and ANG II was assayed in the proximal aorta and coronary sinus. The arterial-venous (A-V) difference of ANG II across the myocardial circulation increased significantly during ANG I infusion (-13.4 +/- 23.5 to 142.8 +/- 71.4 pg/ml; P < 0.03). Subsequent coinfusion of Cap with ANG I significantly decreased the myocardial A-V difference of ANG II by 60 +/- 18% (P < 0.05). Thus, in contrast to the in vitro situation, ANG II formation in vivo is inhibited significantly by Cap in the normal dog heart. This comparison of in vivo and in vitro conversion of ANG I to ANG II by ACE and chymase-like activity suggests that in vitro assays may underestimate the functional contribution of ACE to intracardiac ANG II formation.

An unusual presentation of Smith-Magenis syndrome with iris dysgenesis.

A boy who presented with iris dysgenesis is described. He was shown to have Smith-Magenis syndrome with a deletion of 17p11.2.

HIV infection among women undergoing abortion in Montreal.

OBJECTIVE: To determine the seroprevalence and correlates of HIV infection in a subpopulation of women of childbearing age in Montreal. DESIGN: Anonymous unlinked seroprevalence study. SETTING: Pregnancy termination unit in a teaching hospital in Montreal. PARTICIPANTS: Women presenting for abortion from July 1989 to June 1993 who resided in Quebec and were not known to have HIV infection; 12,017 (99.6%) of 12,068 eligible women were included in the study. INTERVENTION: HIV antibody testing of serum left over from samples obtained for routine Rh typing; the same algorithm as for serodiagnostic testing, namely enzyme immunoassay (EIA) followed by confirmatory testing of repeatedly EIA-reactive samples, was used. OUTCOME MEASURES: HIV serostatus by age, marital status, region of residence (metropolitan Montreal versus other), country of birth and number of living children. RESULTS: Most (84.7%) of the subjects resided in metropolitan Montreal. The median age was 27.0 (range 13 to 50) years. The serum samples of 22 women were confirmed to be HIV positive, for an overall seroprevalence rate of 1.8 per 1000 (95% confidence interval 1.1 to 2.8). The seroprevalence rate did not vary significantly by age, marital status, region of residence or study year. However, it was strongly correlated with country of birth: Canada 0.16, Haiti 23.5, HIV-endemic countries other than Haiti 5.3 and non-HIV-endemic countries other than Canada 0.0 per 1000. The seroprevalence rate among women born in Haiti was 147 times higher than that among women born in Canada (p < 0.0001). Of the women born in Haiti the rate was 3.0 times greater among those who immigrated to Canada in 1985 or later than among those who immigrated earlier (p = 0.047). CONCLUSIONS: The results of this study indicate that the HIV seroprevalence rate among women in Montreal is strongly associated with country of birth, women born in HIV-endemic countries, especially Haiti, having the highest rate. These results will help in the development of policies regarding HIV antibody testing and prevention of HIV transmission in Quebec.

Removal of within-cow differences between morning and evening milk yields.

Methods were explored for removing within-cow differences between a.m. and p.m. milk yields to allow direct comparison of consecutive milk yields. Daily a.m. to p.m. ratios of milk yield were studied for 504 lactations of 310 Holstein cows. Ratios varied within lactations and among cows. When the incomplete gamma function was used to characterize lactation curves, 89% of the variation in individual milk yields was explained when an a.m.-p.m. term was included. The a.m. to p.m. ratios increased over the course of lactations. Within-cow adjustment factors for a.m.-p.m. milking, based on weighted and unweighted averages of previous a.m. to p.m. ratios, changed as lactation length increased. A weighted moving average technique, which weighted the last a.m. to p.m. ratio by .15, compared with .85 for previous ratios, was considered to be the optimal method of calculating a factor for removing a.m.-p.m. effects.

Trisomy 22 and intersex.

Complete trisomy 22, with or without mosaicism, has been reported as a distinct syndrome. In this report an infant is described who was externally male but with female rudimentary internal organs and whose karyotype was 47,XX+22.