Causes Of Calf Mortality Research Articles

Survival and cause‐specific mortality of moose calves in Northeastern Minnesota

ABSTRACTUngulate reproductive success (calf production and survival) influences population performance. The moose (Alces alces) population in northeastern Minnesota, USA, has declined 65% from 2006 to 2018 but has begun to stabilize. Because causes of this decline were largely unknown, we investigated production, survival, and cause‐specific mortality of calves of the global positioning system (GPS)‐collared females in this population. In 2013 and 2014, we GPS‐collared 74 neonates and monitored them for survival. In 2015 and 2016, we monitored 50 and 35 calving females for signs of neonatal mortality using changes in adult female velocities and assessed seasonal calf survival by aerial surveys. In 2013 and 2014 (pooled), survival to 9 months was 0.34 (95% CI = 0.23–0.52) for collared calves, and in 2015 and 2016 (pooled) survival was 0.35 (95% CI = 0.26–0.48) for uncollared calves. Mortality in all 4 years was high during the first 50 days of life. In 2013 and 2014 (pooled), calving sites were relatively safe for collared neonates; predator‐kills occurred a median 17.0 days after departure and a median 1,142 m from calving sites. Predation was the leading cause of death of collared calves (84% of mortalities), with wolves (Canis lupus) accounting for 77% of these. Other forms of mortality for collared and uncollared calves included drowning, infection, vehicle collision, and natural abandonment. We documented higher wolf predation than other recent studies with similar predator communities. Identifying specific causes of calf mortality and understanding their relations to various landscape characteristics and other extrinsic factors should yield insight into mechanisms contributing to the declining moose population in northeastern Minnesota and serve as a basis for ecologically sound management responses. © 2019 The Wildlife Society.

Factors influencing calf mortality in zebu and crossbred cattle reared under subtropical agroclimatic conditions

Data on birth weight and mortality pattern of Zebu (Sahiwal and Tharparkar) and Crossbred (Holstein Friesian × Tharparkar) cattle spread over 16 years were utilized to analyze the causes of calf mortality and to study the effect of non-genetic factors on calf mortality. Calf mortality was higher in crossbred (27.7%) compared to either Sahiwal (20.7%) or Tharparkar cattle (11.9%). Age group wise analysis revealed maximum mortality within one month age in Zebu cattle, and during 1–3 months age in crossbred cattle. Mortality was higher in calves born during winter, summer and rainy seasons in Sahiwal, crossbred and Tharparkar, respectively. Mortality was higher among male calves compared to female calves. Significantly higher proportion of Sahiwal calves died due to respiratory problems, while general debility was the major reason for calf mortality in crossbred and Tharparkar cattle. Season of birth had highly significant influence within one month age in Sahiwal and crossbred cattle. Influence of all the non genetic factors on calf mortality at various age groups was found to be non significant in Tharparkar cattle. It is inferred that calf mortality was higher in crossbred compared to Zebu cattle and the effect of season of birth and birth weight had a significant effect on calf mortality during first three months age. Among the several causes, respiratory problem was a significant reason for the calf mortality.

Survey of reproduction and calf rearing in Asian and African elephants in European zoos

Acyclicity, conception failure, abortion, stillbirth, dystocia, infanticide and neonatal mortality have all been reported as causes of reproductive failure in zoo elephants. These events are often reported as single case reports or in specific studies focused on a particular stage in the reproductive process. In North America wider surveys of reproduction in the zoo elephant population have been completed and repeated to provide data over a number of years. This study is the largest and most comprehensive study of reproduction in the European zoo elephant population to date. Two questionnaires collected data from throughout the reproductive process from assessing cyclicity to independence of the calf at 5 years old. Information was collected regarding 189 birth events. Many causative and contributing factors such as obesity, infectious disease, husbandry, facilities, stress, behaviour, herd size and social grouping have been proposed. The importance of these was assessed and where possible association identified using statistical analysis. In African elephants, this study found that age, obesity, reproductive pathology and dominance, identified as important risk factors for failure to conceive in the American zoo elephant population were of low importance. The most significant cause in Europe was lack of access to a compatible bull. In Asian elephants reproductive failure was much less common but when it did occur age and reproductive pathologies were significant factors as found in previous studies. Previous studies have found that age, obesity and infanticide were considered as the most important risk factors in the period from birth to rearing. In this survey it was found that herd stability and compatibility, allomothering or maternal experience and management at parturition can significantly influence reproductive success. Elephant Endotheliotropic Herpes virus was confirmed as the biggest cause of calf mortality. This work provides evidence to support changes to elephant management in European zoos in order to encourage development of social and affiliative herd behaviours and improve reproductive success.

A survey of management practices that influence performance and welfare of dairy calves reared in southern Brazil.

Here we report dairy calf management practices used by 242 smallholder family farmers in the South of Brazil. Data were collected via a semi-structured questionnaire with farmers, inspection of the production environment and an in-depth interview with a sample of 26 farmers. Herds had an average of 22.3 lactating cows and an average milk production of 12.7 L/cow/day. Calves were dehorned in 98% of the farms, with a hot iron in 95%. Male calves were castrated in 71% of the farms; methods were surgery (68%), emasculator (29%), or rubber rings (3%). No pain control was used for these interventions. In 51% of the farms all newborn male calves were reared, sold or donated to others; in 35% all newborn males were killed on the farm. Calves were separated from the dam up to 12 h after birth in 78% of the farms, and left to nurse colostrum from the dam without intervention in 55% of the farms. The typical amount of milk fed to calves was 4 L/day until a median age of 75 days. In 40% of the farms milk was provided in a bucket, in 49% with bottles, and in 11% calves suckled from a cow. Solid feeding in the milk-feeding period started at a median age of 10 days. Calves were housed individually in 70% of the farms; in 81% of the farms calves were housed in indoor pens, in 6% in outdoor hutches and in 13% they were kept on pasture. Diarrhoea was reported as the main cause of calf mortality in 71% of the farms. Farmers kept no records of calf disease, mortality, or use of medicines. Changing the scenario identified in this survey is essential to support the sustainable development of dairy production, an activity of great economic and social relevance for the region.

Major causes of calf mortality in intensive dairy farms, central Ethiopia: A cohort study

Abstract A cohort study was conducted on 69 live calves from October, 2008 to June, 2009 to identify the risk factors associated with, and the major causes of, calf mortality in the three selected intensive dairy farms at Bishoftu town. The total crude mortality rate found in this study was 11.6 % ( CI=11.38-11.82) while the crude mortality rate of each farm was 0%, 13.6% and 21.7 %, in AB, DF and GC dairy farms respectively. Among the risk factors assessed the amount of colostrums (χ2 =5.14, P = 0.023) and method of colostrum provision (χ2 = 4.83, P = 0.028) were found to be significantly associated with the death of calves while the other risk factors had no significant association with calf mortality. Among the causes of death recorded, calf diarrhea was the leading cause of calf mortality with case specific mortality rate of 5.8%. The present study suggested that the existence of high mortality rates respectively in GC and DF dairy farms might be due to poor calf management recorded in the two farms, especially in GC dairy farm. Hence adequate intake of good quality and quantity of colostrum, good hygienic practices of farms and veterinary services should be ensured; moreover, further investigation is suggested to identify the specific causative agents incriminated for calf mortality in dairy farms of the study area.

Association between calving difficulty score and intrapelvic dimensions, calf hoof circumference, and calf birth weight in Holstein-Friesian cattle

Dystocia in cattle results in pain and suffering, and is an important cause of calf mortality and economic loss in the dairy and beef industries. Accurate prediction of dystocia will facilitate earlier intervention in cattle undergoing parturition. The objective of this study was to determine associations between calving difficulty score and intra pelvic dimensions, calf hoof circumference, and calf birth weight in Holstein-Friesian cattle.

Microbiota bacteriana e citologia da região traqueobrônquica de bezerros no período neonatal

As broncopneumonias são afecções importantes na pecuária mundial, representando uma das principais causas de mortalidade de bezerros nos primeiros meses de vida. As medidas preventivas e terapêuticas adotadas geralmente são baseadas em resultados de estudos internacionais, não se conhecendo as bactérias implicadas nos quadros pneumônicos em animais criados no Brasil. Aliado a isso, no primeiro mês de vida, os bezerros demonstram imaturidade do sistema imune, o que tem sido pouco estudado em quadros pneumônicos. Desta maneira, objetivou-se estudar as broncopneumonias em bezerros neonatos, identificando bactérias do trato respiratório posterior de bezerros sadios e com pneumonias naturalmente adquiridas, bem como analisar citologicamente a resposta pulmonar frente a estes patógenos. Para isso amostras de lavado do trato respiratório foram colhidas por traqueocentese durante o primeiro mês de vida dos animais. Verificou-se que não houve diferença na microbiota traqueobrônquica de bezerros sadios em relação aos doentes, discordando dos relatos da literatura internacional, sendo constituída principalmente por: Staphylococcus sp., Bacillus sp., Streptococcus sp., Pseudomonas aeruginosa e enterobactérias, permitindo inferir que as medidas profiláticas e terapêuticas adotadas internacionalmente possam não ser tão efetivas para as criações brasileiras. Observou-se também que bezerros neonatos têm uma proporção aproximada de 1:1 de macrófagos e neutrófilos na região traqueobrônquica quando saudáveis, atingindo uma relação aproximada de 1:3 durante os quadros de broncopneumonias, sendo estes perfis provavelmente característicos da idade, período conhecido pela imaturidade do sistema imune e agravado por fatores de manejo que favoreçam uma maior inalação de agentes bacterianos.

Enfermidades diagnosticadas em bezerros na região sul do Rio Grande do Sul

O objetivo deste estudo foi relatar a frequência das enfermidades que ocorrem em bovinos até um ano de idade na área de influência do Laboratório Regional de Diagnóstico (LRD) da Faculdade de Veterinária da Universidade Federal de Pelotas (UFPel) estabelecendo os principais fatores epidemiológicos associados à ocorrência dessas enfermidades. Foram revisados os protocolos de necropsias realizadas e de materiais de bovinos até um ano de idade, encaminhados ao LRD/UFPel entre 2000 e 2011. Em 35,6% dos casos, os bezerros eram de raças leiteiras e em 33,98% eram animais de raças de corte, 18,3% dos bezerros não tinham raça definida e em 12,1% dos casos não constava a raça no protocolo de necropsia. Os sistemas mais afetados foram o sistema nervoso central (22,7%), o digestivo (18,6%) e o respiratório (16,8%). Os diagnósticos foram divididos por faixa etária sendo que 88 bezerros tinham 1-90 dias de idade; 42 casos corresponderam a animais de 4-6 meses; 32 casos corresponderam a bezerros com 7-9 meses e 44 eram bezerros com 10-12 meses de idade. As enfermidades mais frequentemente diagnosticadas nos bezerros de 1-90 dias foram pneumonias, malformações e encefalites/meningoencefalites com 19,3%, 15,9% e 11,3% dos casos, respectivamente. Nos bezerros com 4-6 meses de idade, as pneumonias ocorreram em 16,5% dos casos e o carbúnculo sintomático e as enterites representaram 7,1% dos diagnósticos cada. Nos bezerros de 7-9 meses, as enfermidades mais frequentes foram pneumonias e tétano com 9,3% dos casos e babesiose e parasitoses gastrintestinais com 6,2% cada. Nos bezerros de 10-12 meses a infecção por BoHV-5 representou 13,6% dos casos e as pneumonias, a raiva e as parasitoses foram observadas em 9,% dos casos cada. Com base nos resultados deste trabalho pode-se concluir que as doenças infecciosas relacionadas ao sistema respiratório foram importantes causas de mortalidade em bezerros de todas as faixas etárias na área de influência do LRD e sua ocorrência pode ser influenciada por fatores ambientais e pelo manejo. As encefalites/meningoencefalites foram também importantes como causa de mortalidade em bezerros até os três meses de idade.

An investigation into beef calf mortality on five high-altitude ranches that selected sires with low pulmonary arterial pressures for over 20 years

Producer reports from ranches over 2,438 meters in southwest Colorado suggest that the mortality of preweaned beef calves may be substantially higher than the national average despite the selection of low pulmonary pressure herd sires for over 20 years. Diagnostic investigations of this death loss problem have been limited due to the extensive mountainous terrain over which these calves are grazed with their dams. The objective of the current study was to determine the causes of calf mortality on 5 high-altitude ranches in Colorado that have been selectively breeding sires with low pulmonary pressure (<45 mmHg) for over 20 years. Calves were followed from branding (6 weeks of age) in the spring to weaning in the fall (7 months of age). Clinical signs were recorded, and blood samples were taken from sick calves. Postmortem examinations were performed, and select tissue samples were submitted for aerobic culture and/or histopathology. On the principal study ranch, 9.6% (59/612) of the calves that were branded in the spring either died or were presumed dead by weaning in the fall. In total, 28 necropsies were performed: 14 calves (50%) had lesions consistent with pulmonary hypertension and right-sided heart failure, and 14 calves (50%) died from bronchopneumonia. Remodeling of the pulmonary arterial system, indicative of pulmonary hypertension, was evident in the former and to varying degrees in the latter. There is a need to better characterize the additional risk factors that complicate pulmonary arterial pressure testing of herd sires as a strategy to control pulmonary hypertension.

The impact of dystocia on dairy calf health, welfare, performance and survival

Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period. A total of 455 live born Holstein calves (N: No assistance, n=360; FN: Farmer assistance but normally presented calf, n=82; FM: Farmer assistance of malpresented calf, n=13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P<0.001) and FN calves had lower passive immune transfer (P=0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P>0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P<0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8×; P<0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P>0.05). Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia.

Factors affecting calf mortality in Iranian Holstein dairy herds

The objective of this study was to document mortality reasons and risk factors for mortality in dairy calves in the northeast of Iran. This was a prospective cohort study of calves born on ten commercial dairy herds from 21 March 2009 to 20 March 2010. A total of 4097 live calves were followed for 90 days after birth. For each calf details of sex, parity of the dam, type of parturition and season of birth were recorded. The interval (in days) from the date of birth to the date of death and the reason for death was recorded for those calves that died before 90 days of age. A Cox proportional hazards model, including a frailty term to account for unmeasured herd-level effects was developed to quantify the effect of factors associated with time to death.Two hundred and sixty-six (6.5%, 95% CI: 5.8–7.3%) of the 4097 live-born calves died or were euthanised before 90 days of age. The most important reasons for death were digestive tract disorders (58% of all deaths, 95% CI: 52–64%) followed by respiratory diseases (13% of all deaths, 95% CI: 9–17%). Calves exposed to dystocia at birth had 2.09 (95% CI: 1.49–2.92) times the daily hazard of death compared with calves born from a normal calving. The daily hazard of death for calves born in the summer was 1.93 (95% CI: 1.41–2.64) times greater than the hazard for those calves born in the autumn. Inclusion of the herd-level frailty term had a significant effect on hazard estimates indicating that the study herds were heterogeneous in the distribution of unmeasured herd-level factors influencing calf survival.Our results show that diarrhoea is the most important cause of calf mortality in dairy herds in this area of Iran and that environmental and management factors affect calf mortality rate.

Calving rate, calf survival rate, and habitat selection of forest‐dwelling caribou in a highly managed landscape

AbstractLogging negatively affects the threatened forest‐dwelling caribou (Rangifer tarandus caribou) through its positive effects on large predator populations. As recruitment is a key component of caribou population growth rate, we assessed calving rates of females and calf survival rates during the most critical period for calf survival, the calving period. We also identified causes of calf mortality and investigated the influence of predation risk, food availability, and human disturbance on habitat selection of females during the calving period at both the home‐range and forest stand scales. We hypothesized that caribou should display habitat selection patterns to reduce predation risk at both scales. Using telemetry, we followed 22 females and their calves from 2004 to 2007 in a highly managed study area in Québec, Canada. Most females (78.5 ± 0.05 [SE]) gave birth each year, but only 46.3 ± 8.0% of the calves survived during the first 50 days following birth, and 57.3 ± 14.9% of them died from black bear (Ursus americanus) predation. At the home‐range scale, caribou selected calving areas located at upper slope positions and avoided high road density areas. Surprisingly, they also selected the forested habitat type having the lowest lateral cover (mixed and deciduous stands) while avoiding the highest cover (regenerating conifer stands). At the forest stand scale, caribou selected areas located at relatively high elevations and with a lower basal area of black spruce trees. The selection of upper slope positions likely favored spatial segregation between calving females and wolves (Canis lupus) but not black bear. Our results suggest that calving females used areas from which they could visually detect approaching predators. While wolf avoidance appeared to be effective in a highly managed landscape, caribou did not appear to have adjusted their predator avoidance strategy to the recent increase in black bear abundance, who have benefited from increased food abundance. This situation requires focused attention from wildlife managers as logging activities are progressing towards the north within the core of forest‐dwelling caribou range. © 2011 The Wildlife Society.

Risk factors for calf mortality in large Swedish dairy herds

The aim of this study was to identify possible risk factors for 1–90 day calf mortality in large Swedish dairy herds. Sixty herds with a herd size of ≥160 cows were visited once between December 2005 and March 2006. Thirty herds were known to have low mortality (LM) and 30 were known high mortality herds (HM). Upon the visit, data about housing and management was collected from interviews with personnel responsible for the calves. The herd status regarding the calves’ passive transfer (total protein), levels of α-tocopherol, β-carotene and retinol, and excretion of faecal pathogens ( Cryptosporidium spp., Escherichia coli F5, rota and corona virus) was evaluated based on targeted sampling of high risk calf groups; in each herd, blood and faecal samples were collected from calves 1–7 and 1–14 days old, respectively. Similarly, the herd status regarding clinical respiratory disease in calves and history of respiratory virus exposure was evaluated based on lung auscultations and blood samplings of calves 60–90 days old. The median calf mortality risk (in calves 1–90 days of age) among HM herds was 9% (Range: 6–24%) and among LM herds 1% (Range: 0–2%). LM and HM herds were compared using five logistic regression models, covering potential risk factors within different areas: “Disease susceptibility”, “Factors affecting the gastrointestinal tract”, “Factors related to transmission of infectious disease”, “Hygiene” and “Labour management”. The percentage of calves, 1–7 days old, with inadequate serum concentrations of α-tocopherol and β-carotene were significantly higher in HM herds compared to LM herds and also associated with higher odds of being a HM herd (OR = 1.02; p = 0.023 and OR = 1.05; p = 0.0028, respectively). The variable “Average number of faecal pathogens in the sampled target group” was significantly associated with higher odds of being a HM herd (OR = 4.65; p = 0.015), with a higher average in HM herds. The percentage of calves with diarrhoea treated with antibiotics was significantly higher in HM herds and was associated with higher odds of being a HM herd (OR = 1.08; p = 0.021). The median age at death of calves in the age interval 1–90 days that died during a one-year period was significantly lower among HM herds (13 days) than in LM herds (24 days) ( p = 0.0013) The results indicate that gastrointestinal disorders may be an important cause of calf mortality in large Swedish dairy herds. Furthermore, our study provides additional indications that fat soluble vitamins might play an important role for calf health.

Causes of calf mortality in peri-urban area of Nairobi, Kenya

The study reported data from 507 post-mortem records in the Department of Pathology, Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Nairobi, Kenya. The records were from carcasses obtained from the peri-urban area of Nairobi during a 20-year period between 1990 and 2009. Approximately 80% (393/507) of the calf carcasses had their diagnosis made through post-mortem examination, while the rest (114/507) were inconclusive. Just less than half (48.3%) of the calf carcasses presented had their age specified by the owners compared to 51.7% whose age was not specified. For calf carcasses whose age was specified by the owners, those indicated as more than 3 months were one-and-a-half times as many as those below 3 months old. The proportion of female carcasses (53.8%, 273/507) presented for post-mortem were slightly higher than the male carcasses (46.2%, 234/507). Diseases or conditions of the respiratory system were the most common 17.7% (97/507) while gastrointestinal tract (GIT) was second and affected 16.1% (88/507) of the cases. Another small number, 3.3% (18/507), died from bloat giving the total cases associated with GIT as 19.4% (106/507). Severe calf malnutrition and septicaemia were the third most reported causes of calf mortality in similar proportions at 14.3% (78/507) and 14.4% (79/507), respectively. Other minor causes of calf mortality were tick-borne diseases 8.6% (47/507), helminthiasis and poisoning, 2.9% (16/507) and 1.8% (10/507), respectively.

Influence of Predator Harvest, Biological Factors, and Landscape on Elk Calf Survival in Idaho

ABSTRACT We evaluated survival of elk (Cervus elaphus) calves on 2 contrasting study areas in north‐central Idaho, USA, from 1997 to 2004. Recruitment was modest (&gt;30 calves:100 F [calves of either sex: F elk 1 yr old]) and stable on the South Fork study area and low (&lt;20 calves:100 F) and declining on the Lochsa study area. The primary proximate cause of calf mortality on both study areas was predation by black bears (Ursus americanus) and mountain lions (Puma concolor). We experimentally manipulated populations of black bears and mountain lions on a portion of each study area. Black bear harvest (harvest density/600km2) initially doubled on the Lochsa treatment after manipulating season bag limits. Mountain lion harvest also increased by 60% but varied widely during the manipulation period. Harvest seasons were closed for black bears and mountain lions on the treatment portion of the South Fork study area. Using the Andersen—Gill formulation (A‐G) of the Cox proportional hazards model, we examined effects of landscape structure, predator harvest levels, and biological factors on summer calf survival. We used Akaike's Information Criterion (AICc) and multimodel inference to assess some potentially useful predictive factors relative to calf survival. We generated risk ratios for both the best models and for model‐averaged coefficients. Our models predicted that calf survival was influenced by biological factors, landscape surrounding calf locations, and predator harvest levels. The model that best explained mortality risk to calves on the Lochsa included black bear harvest (harvest density/600 km2), estimated birth mass of calves, and percentage of shrub cover surrounding calf locations. Incorporating a shrub X time interaction allowed us to correct for nonproportionality and detect that effect of shrub cover was only influential during the first 14 days of a calf's life. Model‐averaging indicated that estimated birth mass of calves and black bear harvest were twice as important as the next variables, but age of calves at capture was also influential in calf survival. The model that best explained mortality risk to calves on the South Fork included black bear harvest, age of calves at capture, and gender of calves. Model‐averaging indicated that age at capture and black bear harvest were twice as important as the next variable, forest with 33–66% canopy cover (Canopy 33–66). Risk to calves decreased when calves occupied areas with more of this forest cover type. Model‐averaging also indicated that increased mountain lion harvest lowered calf mortality risk 4% for every 1‐unit increase in lion harvest (harvest density/600 km2) but was lower (&lt;25%) in importance compared to age at capture and black bear harvest. Our results suggest that levels of predator harvest, and presumably predator density, resource limitations expressed through calf birth mass, and habitat structure had substantial effects on calf survival. Our results can be generalized to other areas where managers are dealing with low calf elk recruitment. However, because factors vary spatially, a single management strategy applied in different areas will probably not have the same effect on calf survival.

Effects of a prebiotic supplement on health of neonatal dairy calves

Calf morbidity and mortality represent major financial losses for many dairy producers. The primary cause of calf mortality in the U.S. is diarrhea caused by intestinal bacterial infections. Traditionally, formulated antibiotics in milk replacer have been used as preventive treatments. However, as consumer concern about antibiotic resistance has increased, interest in alternative supplements has grown. Prebiotics, which are food ingredients not digestible by animal enzymes, and probiotics, which are beneficial bacteria, are two proposed alternatives for antibiotics to reduce diarrhea and improve immunity in calves. In this trial 75 Holstein heifer calves were randomly assigned to one of 3 treatments: control (C; no additive), antibiotic treatment (A; oxytetracycline 0.220 g/kg and neomycin base 0.441 g/kg), and prebiotic supplement (PB; 20 g/day Prebio Support™, Meiji Feed Co., Ltd. Tokyo, Japan). Calf scours, respiratory, and general appearance scores were not affected by treatment. No statistical differences were detected in any of the health data collected; however, treatment C had nearly twice as many calves that scoured and refused feed than treatments A and PB. Populations of beneficial and pathogenic bacteria in feces were generally not affected by treatments. However, PB treatment calves had an overall trend for more Lactobacilli in their feces than calves fed A ( P = 0.08), and Enterobacter population was greater in C calves than in calves on treatment A in week 4 ( P < 0.05). There was a tendency for the PB treatment to have elevated populations of beneficial species of bacteria during week 2. Populations of lymphocytes carrying CD4 and CD8 markers were not affected by treatment. Fecal IgA concentration decreased as calf age increased, with the greatest concentration in week 2 ( P < 0.01) for all calves. Fecal IgA levels were numerically greater for the PB group in weeks 2 and 4. Both PB and A treatments affected fecal parameters with PB having positive effects in several areas. Since calves in this study were generally healthy, observable benefits from the treatments were likely minimized.

Reducing Dairy Calf Mortality

The loss of dairy calves from stillbirths and disease-related deaths places a significant challenge on the producer who wants farm-specific replacement heifers to maintain or expand herd size. Stillbirths are often overlooked as an important cause of calf mortality, as they are on some dairies. With improved record keeping, data analysis, diagnostic testing and herd monitoring, the appropriate risk factors for stillbirth can be broken down and targeted for improvement. The classification of stillbirths will need to be broadened, however, and the role of maternal stress, metabolic disorders, fetal growth factors and environmental exposure may need attention to solve this growing cause of calf mortality. Solving disease related death problems in dairy calves requires a broad approach that looks not only for the disease agents but for the sources of infection, opportunities to improve immunity and changes that can reduce the susceptibility of calves. Once affected, the difference between disease morbidity and calf mortality is early detection and appropriate intervention with effective treatment protocols. Colostrum management, health screening, diagnostic testing, overview of bedding management, feeding consistency, simplicity, as well as the implementation of effective preventive and therapeutic strategies bring the veterinarian to the forefront of reducing calf morbidity and mortality.

Surviving at sea: ecological and behavioural predictors of calf mortality in Indian Ocean bottlenose dolphins, Tursiops sp.

We examined the behavioural ecology of mothers and calves during the first year of life to identify variables predicting calf mortality among bottlenose dolphins. Specifically, we investigated whether the primary cause of calf mortality was poor calf condition or shark predation. Seventy-five per cent of calves that died (N = 12) showed visible signs of poor health compared with 4.7% of the survivors (N = 21). Calves that spent more time swimming in infant position (in contact under the mother) in the first year of life were more likely to die by 3 years of age than calves that spent less time swimming in infant position. No other behavioural or ecological measures tested were associated with calf mortality. We suggest that the mother and/or calf may compensate for poor calf health by increasing the time spent in contact with the mother. In contrast, frequent mother–calf separation and high rates of calf socializing and foraging are proposed to be indicators of vigour. Although most of our results do not support the predation hypothesis, mothers altered one behaviour in relation to predation risk. Mothers rested less in deep water during the warm months, where and when predation risk was high, than during the cool months, when predation risk was low, suggesting that predation risk influenced maternal vigilance. However, calf mortality was not higher in warm months than in cool months. Our results suggest that poor calf condition, not predation, is the primary cause of calf mortality.

Calf mortality and population growth in the Delta caribou herd after wolf control

Abstract A program to control wolves (Canis lupus) in interior Alaska in 1993 and 1994 did not result in expected increases in calf survival in the Delta caribou (Rangifer tarandus) herd (DCH). Therefore, the Alaska Department of Fish and Game conducted a study to determine causes of calf mortality during 1995–1997 and monitored recruitment, mortality, and population size annually in the DCH for 6 years after wolf control ended. Despite removal of 60–62% of the autumn 1993 wolf population, wolves still killed 25% of 166 radiocollared calves between birth in mid- to late May and 30 September during 1995–1997. Although autumn calf:cow ratios in the DCH increased after wolf control, similar increases in calf:cow ratios occurred in the adjacent Denali Herd, where wolves were not controlled. Calf:cow ratios following wolf control in 1993 and 1994 were lower than ratios obtained in the same area after wolf control from 1976–1982. We identified 4 factors that contributed to continued low calf:cow ratios in the D...

DIFFERENCES IN PERCEPTION OF CAUSES OF CAMEL CALF LOSSES BETWEEN PASTORALISTS AND SCIENTISTS

Management deficiencies on the part of the pastoralists were claimed to be one of the major causes of the high losses of camel (Camelus dromedarius) calves contributing to low productivity of camel herds. In the present study, calf deaths, and the causes thereof, were analysed in connection with pastoral calf management in order to assess possible relationships. Progeny history data on 1506 Rendille, 789 Gabra and 1206 Somali calves born between 1980 and 1995 provided quantitative information on losses and the underlying causes. Assessment of the causes of death, and analysis of related management practices, led to suggestions for management changes. In feedback seminars with pastoralists, however, it became apparent that these management changes would not be adopted because they contradicted the pastoralists' assumptions on the causes of calf mortality. The discussions revealed that differences between pastoralists' and scientists' perceptions determined different opinions on proper calf-rearing management practices. Combining different knowledge systems offers the possibility of a more complete understanding, which is required for the derivation of adoptable calf mortality-reducing interventions that are compatible with the knowledge and production systems of the pastoralists.