Selection for increased weaning or yearling weight in Hereford cattle. I. Measurement of selection applied

Selection was applied from 1964 to 1978 for increased weaning weight (WWL) or yearling weight (YWL) in two Hereford lines with an Angus line maintained as an unselected control line (CL). Each line was maintained with 50 cows and four sires (two sires selected each year and each used for 2 yr). Traits analyzed were birth weight (BW), preweaning daily gain (WDG), weaning weight (WW), weaning conformation grade (WG), weaning condition score (WC), weaning to yearling daily gain (YDG), yearling weight (YW), yearling conformation grade (YG) and yearling condition score (YC). After 15 yr of selection, a total of 3.22 generations of selection had occurred in both WWL and YWL. Average selection differentials in standard measure per generation for WWL, YWL and CL, respectively, were: BW, .44, .51, .0; WDG, .95, .81, .09; WW, .97, .85, .09; WG, .66, .57, .09; WC, .60, .38, -.02; YDG, .30, .79, .38; YW, .80, 1.05, .25; YG, .63, .62, .34 and YC, .45, .64, .24. The proportionate contribution of sire selection (delta S) to the average midparent selection differential per generation (delta M) was 70% in WWL and 76% in YWL. Selection indexes in retrospect were also calculated.     

Assessing the influence of mechanical ventilation on blood gases and blood pressure in rattlesnakes

ObjectiveTo characterize the impact of mechanical positive pressure ventilation on heart rate (HR), arterial blood pressure, blood gases, lactate, glucose, sodium, potassium and calcium concentrations in rattlesnakes during anesthesia and the subsequent recovery period.Study designProspective, randomized trial.AnimalsTwenty one fasted adult South American rattlesnakes (Crotalus durissus terrificus).MethodsSnakes were anesthetized with propofol (15 mg kg⁻¹) intravenously, endotracheally intubated and assigned to one of four ventilation regimens: Spontaneous ventilation, or mechanical ventilation at a tidal volume of 30 mL kg⁻¹ at 1 breath every 90 seconds, 5 breaths minute⁻¹, or 15 breaths minute⁻¹. Arterial blood was collected from indwelling catheters at 30, 40, and 60 minutes and 2, 6, and 24 hours following induction of anesthesia and analyzed for pH, PaO₂, PaCO₂, and selected variables. Mean arterial blood pressure (MAP) and HR were recorded at 30, 40, 60 minutes and 24 hours.ResultsSpontaneous ventilation and 1 breath every 90 seconds resulted in a mild hypercapnia (PaCO₂ 22.4 ± 4.3 mmHg [3.0 ± 0.6 kPa] and 24.5 ± 1.6 mmHg [3.3 ± 0.2 kPa], respectively), 5 breaths minute⁻¹ resulted in normocapnia (14.2 ± 2.7 mmHg [1.9 ± 0.4 kPa]), while 15 breaths minute⁻¹ caused marked hypocapnia (8.2 ± 2.5 mmHg [1.1 ± 0.3 kPa]). Following recovery, blood gases of the four groups were similar from 2 hours. Anesthesia, independent of ventilation was associated with significantly elevated glucose, lactate and potassium concentrations compared to values at 24 hours (p < 0.0001). MAP increased significantly with increasing ventilation frequency (p < 0.001). HR did not vary among regimens.Conclusions and clinical relevanceMechanical ventilation had a profound impact on blood gases and blood pressure. The results support the use of mechanical ventilation with a frequency of 1–2 breaths minute⁻¹ at a tidal volume of 30 mL kg⁻¹ during anesthesia in fasted snakes.     

Evaluation of the oral 13C-bicarbonate technique for measurements of energy expenditure in dogs before and after body weight reduction

Background

Overweight and obesity are the most common nutritional disorders in dogs and may lead to various secondary diseases and decreased lifespan. In obesity research, measurement of energy expenditure (EE) and determination of the energy requirements are essential. The objective with this study was to validate and evaluate the suitability of the oral ¹³C-bicarbonate technique (o¹³CBT) for measuring EE in dog obesity studies. A further objective was to investigate the impact of body weight (BW) reduction and changes in body composition on the EE when measured under conditions corresponding to the basal metabolic rate (BMR).

Results

The EE in five privately owned, overweight dogs was measured simultaneously with the o¹³CBT and indirect calorimetry (IC) for comparison of the results. Two measurements per dog were performed under the same standardised conditions (i.e. fasted and resting state) at the start, and after completing a 12-week BW reduction program. Additionally, measurements of body composition by Dual-energy X-ray absorptiometry (DEXA) were conducted at the beginning and at the end of the BW reduction program. There were no differences in EE results obtained by the o¹³CBT and IC. Overweight and the BW reduction did not affect the estimates for the respiratory quotient (RQ) or the recovery factor for the ¹³C-tracer (RF), both needed when using the o¹³CBT. The dogs lost 16% (SD ± 2.0) of their initial BW in reduced fat mass (P < 0.001), whereas fat free mass (FFM) remained unchanged. There was no effect of the BW reduction on the determined EE expressed in kJ/kg BW/d, or in kJ/kg BW^0.75/d. However, EE was lower (P < 0.001) after the BW reduction program when expressed in relation to FFM (kJ/kg FFM/d).

Conclusions

Results from the present study show that the o¹³CBT can be a used in obesity research to determine EE in fasted dogs and under resting conditions. Furthermore, the results suggest that the BMR does not change with reduced BW in overweight dogs as long as the FFM remains unchanged. This indicates that the BMR to maintain one gram of fat is equal to maintaining one gram of FFM in overweight dogs.     

A Large‐scale,Rapid Public Health Response to Rabies in an Organ Recipient and the Previously Undiagnosed Organ Donor

This article describes and contrasts the public health response to two human rabies cases: one organ recipient diagnosed within days of symptom onset and the transplant donor who was diagnosed 18 months post‐symptom onset. In response to an organ‐transplant‐related rabies case diagnosed in 2013, organ donor and recipient investigations were conducted by multiple public health agencies. Persons with potential exposure to infectious patient materials were assessed for rabies virus exposure. An exposure investigation was conducted to determine the source of the organ donor's infection. Over 100 persons from more than 20 agencies spent over 2700 h conducting contact investigations in healthcare, military and community settings. The 564 persons assessed include 417 healthcare workers [5.8% recommended for post‐exposure prophylaxis (PEP)], 96 community contacts (15.6% recommended for PEP), 30 autopsy personnel (50% recommended for PEP), and 21 other persons (4.8% recommended for PEP). Donor contacts represented 188 assessed with 20.2% recommended for PEP, compared with 5.6% of 306 recipient contacts recommended for PEP. Human rabies cases result in substantial use of public health and medical resources, especially when diagnosis is delayed. Although rare, clinicians should consider rabies in cases of encephalitis of unexplained aetiology, particularly for cases that may result in organ donation.     

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems: III. Productivity as three-, four-, and five-year olds

Productivity of 3-, 4-, and 5-yr-old crossbred cows containing various proportions (0, 1/4, or 1/2) of Brahman breeding out of Angus or Hereford dams was evaluated using 489 spring-calving and 427 fall-calving records collected over a 4-yr period. Cows were bred to Limousin sires for the first 3 yr and to Limousin and Salers sires the 4th yr. Interactions between crossbred cow group and season of calving were not significant. Percentage of cows exposed to breeding that weaned a calf increased (P less than .01) as proportion Brahman breeding increased, was higher (P less than .01) for cows out of Angus dams than for cows out of Hereford dams, and was higher (P less than .01) for spring-calving cows. As the proportion Brahman increased, the percentage requiring assistance at birth decreased, and cows out of Angus dams required less (P less than .05) assistance than those out of Hereford dams. Preweaning ADG, adjusted weaning weight, weaning conformation, weaning condition, and adjusted weaning hip height increased a proportion Brahman breeding increased. Spring-born calves gained .12 kg/d faster (P less than .01) than fall-born calves. However, weight at weaning was similar for the two groups; spring-born calves were weaned at an average age of 205 d, and fall-born calves were weaned at an average age of 240 d. Fall-calving cows were heavier (P less than .05) than spring-calving cows, and 0 and 1/2 Brahman cows were heavier (P less than .01) than 1/4 Brahman cows. These data indicate that Brahman-cross dams can be used to improve reproductive rate and increase preweaning growth rate, and thus weaning weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems: II. Milk production

Monthly estimates of 24-h milk yield were obtained on 160 spring-calving and 153 fall-calving crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding, all bred to Limousin sires. Milk production was measured using weigh-suckle-weigh procedures. Interactions between crossbred group and season of calving were not significant. Across seasons, milk production rarely was affected by proportion of Brahman breeding; however, milk yield, averaged over six monthly measurements, was greater (P less than .10) for cows out of Hereford dams than for cows out of Angus dams. Averaged over six monthly measurements, estimated 24-h milk yield ranged from 5.3 kg for Hereford x Angus to 6.2 kg for Brahman x Hereford cows. Season of calving affected milk yield during the first and fourth measurement periods. Fall-calving cows produced more (P less than .01) milk during the first period whereas spring-calving cows produced more milk during the fourth period. Lactation patterns for the two seasons differed. Spring-calving cows had a more typical lactation curve, whereas the curve for fall-calving cows showed more variability in milk yield throughout lactation. Phenotypic correlations between monthly measurements of 24-h milk yield and calf performance tended to be moderate and positive within the spring group. Correlations for the fall group, although positive, tended to be weaker than those found in the spring group.     

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems. I. Productivity as two-year-olds

Productivity of 2-yr-old crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding was evaluated using 203 spring-calving and 171 fall-calving heifers over a 3-yr period. All heifers were mated to Limousin sires. Percentage of cows exposed to breeding that weaned a calf was the only trait for which a significant crossbred cow group x season of calving interaction was found. Preweaning ADG and age-adjusted weaning weight increased as proportion Brahman breeding increased. Age-adjusted weaning weight was similar for the two groups because spring-born calves were weaned at an average age of 205 d and fall-born calves were weaned at an average age of 240 d. For weaning condition scores, an interaction between dam breed and proportion Brahman was detected; scores tended to be greater for calves out of 1/2 Hereford dams than for those out of 1/2 Angus dams, and this difference increased as proportion Brahman increased. Weaning conformation scores were similar for all calves. Age-adjusted weaning hip height increased as proportion Brahman breeding increased. Based on numbers of weaned calves, spring calving was more advantageous than fall calving. Averaged across both calving seasons, weaning weight tended to increase as proportion Brahman increased.     

Reinventing rural development in Vietnam: Discursive constructions of grassroots democracy during the renovation reform

Over the past decades Vietnam has seen striking efforts to reinvent the exercise of democratic rural development. Promotion of grassroots democracy, notably under the Grassroots Democracy Decree (GDD), has been an acute response by Communist Party and government to large scale unrest among the rural populace owing to dissatisfactions with a felt mismatch between espoused commitments to ‘good governance’ and its actual practice. Through evidence from field work, this paper assesses the implications of the GDD in the central and northern highlands, analyzing how the promotion of grassroots democracy is discursively constructed by rural development professionals. The results outline three dominant discourses, which center on their respective interests in liberalist democratization, improved efficiency in state renovation, and enhanced accountability in governing local policy ambiguities. It argues that ‘grassroots democracy’ is serving as a conceptual mediator, supporting learning between diverging interests associated with rural development and different ideological positions shrouding the notion of democracy itself. Yet, given the extent that discourses are reflective of how professionals relate to grassroots aspirations, grassroots movements, which originally ushered the Party and central government to pass the GDD, have a significant struggle ahead of them to affect concrete changes in professionals' practices.