Genetic analysis of phenotypic indicators for heat tolerance in crossbred dairy cattle

Climate change-induced rise in global temperatures has intensified heat stress on dairy cattle and is contributing to the generally observed low milk productivity. Selective breeding aimed at enhancing animals’ ability to withstand rising temperatures while maintaining optimal performance is crucial for ensuring future access to dairy products. However, phenotypic indicators of heat tolerance are yet to be effectively factored into the objectives of most selective breeding programs. This study investigated the response of milk production to changing heat load as an indication of heat tolerance and the influence of calving season on this response in multibreed dairy cattle performing in three agroecological zones Kenya. First-parity 7-day average milk yield (65 261 milk records) of 1 739 cows were analyzed. Based on routinely recorded weather data that were accessible online, the Temperature-Humidity Index (THI) was calculated and used as a measure of heat load. THI measurements used represented averages of the same 7-day periods corresponding to each 7-day average milk record. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: slope of the reaction norm (Slope) and its absolute value (Absolute), reflecting changes in milk yield in response to the varying heat loads (THI 50 and THI 80). The genetic parameters of these indicators were estimated, and their associations with average test-day milk yield were examined. There were no substantial differences in the pattern of milk yield response to heat load between cows calving in dry and wet seasons. Animals with ≤50% Bos taurus genes were the most thermotolerant at extremely high heat load levels. Animals performing in semi-arid environments exhibited the highest heat tolerance capacity. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero (P &lt; 0.05). Slope at THI 80 had high (0.64–0.71) negative correlations with average daily milk yield, revealing that high-producing cows are more vulnerable to heat stress and vice versa. A high (0.63–0.74) positive correlation was observed between Absolute and average milk yield at THI 80. This implied that low milk-producing cows have a more stable milk production under heat-stress conditions and vice versa. The study demonstrated that the slope of the reaction norms and its absolute value can effectively measure the resilience of crossbred dairy cattle to varying heat load conditions. The implications of these findings are valuable in improving the heat tolerance of livestock species through genetic selection.</p

Enhancing individual animal resilience to environmental disturbances to address low productivity in dairy cattle performing in sub-Saharan Africa

The current review examines potential solutions to enhance the sustainability and productivity of the dairy sector in sub-Saharan Africa (SSA) with an emphasis on breeding for resilience. Additionally, the paper explores various indicators for measuring resilience and provides insights into the data that can be utilized to quantify resilience in SSA’s dairy production systems. Dairy production contributes significantly to food and nutritional security and employment in SSA. However, besides the general lack of enabling policy and institutional environments, production is negatively affected by environmental challenges such as high temperatures and heat stress, diseases and parasites, unreliable rainfall patterns, shortages of feeds and forages and undue preference for taurine cattle breeds regardless of their poor adaptability to prevailing local conditions. Fostering the resilience capacity of dairy animals is imperative to combat climate-related adversities and maintain productivity. This can only be achieved if reliable and practical methods for quantifying and analyzing resilience in SSA are described and undertaken. This study has reviewed variance of deviations, root mean square of deviations, autocorrelation of deviations, skewness of deviations, slope of the reaction norm and its absolute value as possible indicators of resilience in SSA. While previous research has reported genetic variation and favorable correlations of these indicators with health, fitness, and fertility traits, their potential in SSA environments requires further investigation. Besides, labor- and cost-effective phenotypic data collection is essential for characterization of resilience using these indicators. Through this study, we propose frequently collected data on milk production traits, body fat-related traits, and activity patterns as suitable in the sub-Saharan Africa context. The African Asian Dairy Genetic Gains Project by the International Livestock Research Institute (ILRI) offers a valuable opportunity to collate data from diverse dairy systems in SSA for testing the potential of these indicators. Insights from this study are helpful in improving resilience of dairy animals in SSA, which would contribute to poverty alleviation, animal welfare improvement, and better preparedness in lieu of climate change in SSA.</p

Timing of surgery following SARS-CoV-2 infection: an international prospective cohort study.

Peri-operative SARS-CoV-2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS-CoV-2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre-operative SARS-CoV-2 infection were compared with those without previous SARS-CoV-2 infection. The primary outcome measure was 30-day postoperative mortality. Logistic regression models were used to calculate adjusted 30-day mortality rates stratified by time from diagnosis of SARS-CoV-2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre-operative SARS-CoV-2 diagnosis. Adjusted 30-day mortality in patients without SARS-CoV-2 infection was 1.5% (95%CI 1.4-1.5). In patients with a pre-operative SARS-CoV-2 diagnosis, mortality was increased in patients having surgery within 0-2 weeks, 3-4 weeks and 5-6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3-4.8), 3.9 (2.6-5.1) and 3.6 (2.0-5.2), respectively). Surgery performed ≥ 7 weeks after SARS-CoV-2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9-2.1)). After a ≥ 7 week delay in undertaking surgery following SARS-CoV-2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2-8.7) vs. 2.4% (95%CI 1.4-3.4) vs. 1.3% (95%CI 0.6-2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS-CoV-2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay

Effects of antibiotic resistance, drug target attainment, bacterial pathogenicity and virulence, and antibiotic access and affordability on outcomes in neonatal sepsis: an international microbiology and drug evaluation prospective substudy (BARNARDS)

Background Sepsis is a major contributor to neonatal mortality, particularly in low-income and middle-income countries (LMICs). WHO advocates ampicillin–gentamicin as first-line therapy for the management of neonatal sepsis. In the BARNARDS observational cohort study of neonatal sepsis and antimicrobial resistance in LMICs, common sepsis pathogens were characterised via whole genome sequencing (WGS) and antimicrobial resistance profiles. In this substudy of BARNARDS, we aimed to assess the use and efficacy of empirical antibiotic therapies commonly used in LMICs for neonatal sepsis. Methods In BARNARDS, consenting mother–neonates aged 0–60 days dyads were enrolled on delivery or neonatal presentation with suspected sepsis at 12 BARNARDS clinical sites in Bangladesh, Ethiopia, India, Pakistan, Nigeria, Rwanda, and South Africa. Stillborn babies were excluded from the study. Blood samples were collected from neonates presenting with clinical signs of sepsis, and WGS and minimum inhibitory concentrations for antibiotic treatment were determined for bacterial isolates from culture-confirmed sepsis. Neonatal outcome data were collected following enrolment until 60 days of life. Antibiotic usage and neonatal outcome data were assessed. Survival analyses were adjusted to take into account potential clinical confounding variables related to the birth and pathogen. Additionally, resistance profiles, pharmacokinetic–pharmacodynamic probability of target attainment, and frequency of resistance (ie, resistance defined by in-vitro growth of isolates when challenged by antibiotics) were assessed. Questionnaires on health structures and antibiotic costs evaluated accessibility and affordability. Findings Between Nov 12, 2015, and Feb 1, 2018, 36 285 neonates were enrolled into the main BARNARDS study, of whom 9874 had clinically diagnosed sepsis and 5749 had available antibiotic data. The four most commonly prescribed antibiotic combinations given to 4451 neonates (77·42%) of 5749 were ampicillin–gentamicin, ceftazidime–amikacin, piperacillin–tazobactam–amikacin, and amoxicillin clavulanate–amikacin. This dataset assessed 476 prescriptions for 442 neonates treated with one of these antibiotic combinations with WGS data (all BARNARDS countries were represented in this subset except India). Multiple pathogens were isolated, totalling 457 isolates. Reported mortality was lower for neonates treated with ceftazidime–amikacin than for neonates treated with ampicillin–gentamicin (hazard ratio [adjusted for clinical variables considered potential confounders to outcomes] 0·32, 95% CI 0·14–0·72; p=0·0060). Of 390 Gram-negative isolates, 379 (97·2%) were resistant to ampicillin and 274 (70·3%) were resistant to gentamicin. Susceptibility of Gram-negative isolates to at least one antibiotic in a treatment combination was noted in 111 (28·5%) to ampicillin–gentamicin; 286 (73·3%) to amoxicillin clavulanate–amikacin; 301 (77·2%) to ceftazidime–amikacin; and 312 (80·0%) to piperacillin–tazobactam–amikacin. A probability of target attainment of 80% or more was noted in 26 neonates (33·7% [SD 0·59]) of 78 with ampicillin–gentamicin; 15 (68·0% [3·84]) of 27 with amoxicillin clavulanate–amikacin; 93 (92·7% [0·24]) of 109 with ceftazidime–amikacin; and 70 (85·3% [0·47]) of 76 with piperacillin–tazobactam–amikacin. However, antibiotic and country effects could not be distinguished. Frequency of resistance was recorded most frequently with fosfomycin (in 78 isolates [68·4%] of 114), followed by colistin (55 isolates [57·3%] of 96), and gentamicin (62 isolates [53·0%] of 117). Sites in six of the seven countries (excluding South Africa) stated that the cost of antibiotics would influence treatment of neonatal sepsis

Persistency of lactation and comparison of different persistency measures in indigenous and crossbred cows at Bako, Ethiopia

Persistency of lactation in indigenous and crossbred cows was studied using milk data collected at Bako Agricultural Research Centre. Persistency was measured using three methods vis a vis as the ratios of milk yield during the second (P2:1) and third (P3:1) 100 days of lactation to milk yield during the first 100 days of lactation, and using persistency index (PI). The overall mean P2:1, P3:1 and PI were 78.0±0.67, 59.2±0.58 and 85.7±0.70 percent, respectively. P2:1 was significantly (P<0.01) affected by sire breed, calving season and initial milk yield, while P3:1 and PI were significantly (at least P<0.05) affected by sire breed, calving season, calving weight and initial milk yield. Among the sire breed categories, Simmental crosses had significantly the highest P2:1 (86.7±1.93%), P3:1(67.9±2.14%) and PI (90.5±1.65%) while the Horro had the lowest values of these traits. Cows that calved during Bona (December to February) had the highest P2:1 (88.2±1.58%). The lowest P3:1 (46.9±2.22 %) and PI (77.2±1.82°/a) were recorded for cows that calved during Arfasa (March to May). Calving weight was linearly related to P3:1 (b = -0.08±0.02; P < 0.001) and PI (b = 0.04±0.02; P < 0.05)_ Similarly, initial milk yield was linearly and negatively related to P2:1 (b = L14±0.31; P < 0.001), P3:1 (b = 0.88±0.38; P < 0.05) and PI (b = 0.65±0.31; P < 0.05). All persistency values obtained in this study were lower for indigenous breeds than crossbreds indicating that these traits were improved through crossbreeding. Persistency was also affected by calving season, calving weight and initial milk yield, which are probably related to the availability of feed. Thus, improving the feeding system through strategic supplementation might improve persistency in both indigenous and crossbred cows. Besides, due to shorter lactation length of most indigenous cows and for periodic assessment of persistency of crossbred cows to make improvement interventions in the meantime, P2:1 and P3:1 are more appropriate compared to persistency index

Postpartum anoestrus interval and estrus activity in relation to postpartum body weight dynamics in indigenous and crossbred cows at Bako, Ethiopia

Postpartum anoestrus interval (PPAI) and estrus activity measured as probability of getting acow in estrus within 42 (PPAI42), 63 (PPAI63) and 84 (PPAI84) days postpartum in indigenousand crossbred cows were studied using data from Bako Agricultural Research Center. PPAI wasanalyzed using the General Linear Model, while PPAI42, PPAI63 and PPAI84 were analyzedusing the Categorical Model Procedure of the Statistical Analysis System and LOGMLVARcomputer program. The results of the analysis indicated an overall least square mean PPAI of79.4 ± 1.99 days. Comparisons of the different genotypes, parities, calving seasons and yearsindicated that Boran x Simmental cross cows (136.9 ± 10.86 day), cows in the first parity (118.3 ±7.57 days), cows that calved during March to May (105.3 ± 5.78 days) and those that calved in1984 (128.3 ± 11.01 days) had significantly (P < 0.001) the longest PPAI. PPAI was significantly(P < 0.001) related to calving weight (b = -0.53 ± 0.14) and body weight gain from calving to threemonths (b= -0.04 ± 0.02). The overall mean predicted probability for PPAI42, PPAI63 and PPAI84were 0.33 ± 0.02, 0.53 ± 0.02 and 0.68 ± 0.02, respectively. Among the sire breeds, the Horro andJersey had significantly (at least P < 0.05) the highest PPAI42, PPAI63 and PPAI84 while as adam breed, the Horro had significantly (at least P < 0.01) higher PPAI42, PPAI63 and PPAI84than Boran cows. Cows in the later parities (5 to 6) had significantly (P < 0.05) highest PPAI42,PPAI63 and PPAI84 compared to cows in earlier parities (1-4). Calving weight showed asignificant (P < 0.001) effect on PPAI42, PPAI63 and PPAI84 and all those traits increased withincrease in calving weight. This study indicated the importance of calving weight and postpartumbody weight gain in affecting PPAI and estrus activity. Thus, improvement in these traits couldbe achieved through improvement of the calving weight and postpartum body weight gain

Dairy investment options for poverty reduction for small-scale dairy farmers in Tanzania

The effect of an unproductive investment could be detrimental to the investor, especially when is a dairy farmer investor who depend on earnings and may distort the productivity effort if is not approached with caution. Anyone who wish to invest in dairy farming must choose wisely, think independently to avoid follow the crowd. Ideal investment decisions in dairy would starts by best choice of breeds, feeds availability, affordability and accessibility, knowledge in proper animal husbandry and proper handling and marketing of animal products. Most farmers in Tanzania who are in dairy farming invested with different objectives, such as for prestige, for family nutrition, for manure and sale of live calves, to mention a few. This study investigating dairy cow investment and how it affects poverty situation in the families. The results show that investment in the dairy sector is the key to reliable income and leaning pole to poverty reduction in the family. Therefore, choice in investment may affect income and reduce poverty in two folds if it is done in ideal situation