Cold thermoregulation in the newborn calf

Influence of proportion of Brahman genetics on productivity of Brahman-Angus cows at weaning

This study evaluated the association between the proportion of Brahman genetics and productivity of Brahman-Angus cows at weaning using a 31-yr dataset containing 6,312 cows and 5,405 pregnancies. Cows were contemporaneously reared and enrolled in yearly breeding seasons under subtropical conditions of North-Central Florida. They were evenly distributed in six-breed groups (G) according to the proportion of Brahman genetics: G0% to 19%, G21% to 34%, G38% (Brangus), G41% to 59%, G63% to 78%, and G81% to 100%. The proportion of cows calving (84.9%) did not differ across the six-breed groups. However, cows in the G81% to 100% weaned fewer calves (90.8%) than cows in the G0% to 19% and G21% to 34% (95.7%, each). The weaning rate of cows in the G38% (94.3%), G41% to 59% (94.2%), and G63% to 78% (93.0%) was intermediate between these three breed groups. The preweaning calf mortality was greater for cows in the G81% to 100% (9.2%) than cows in the G0% to 19% and G21% to 34% (4.3%, each), but intermediate for cows in the G38% (5.7%), G41% to 59% (5.8%), and G63% to 78% (7.0%). Cows in the G81% to 100% also weaned lighter calves (220.6 kg) than cows in the G0% to 19% (245.2 kg), G21% to 34% (250.2 kg), G38% (247.9 kg), G41% to 59% (252.5 kg), and G63% to 78% (245.2 kg). Cows in the G0% to 19% weaned lighter calves than cows with 21% to 78% of Brahman genetics. The 205-d adjusted weaning weight evidenced the less productive results of cows in G0% to 19% and G81% to 100% compared with other genetic groups, as they calved at the fastest and slowest rate, respectively. Thus, the 205-d adjusted weaning weight eliminated this bias. Additionally, younger cows weaned lighter calves; and male calves were heavier at weaning than female calves. Both parity order of cow and calf sex altered the magnitude of the described association between breed group of cows and calf weaning weights. Overall, after adjusting for weaning rate and age of calves at weaning, the number of kilograms produced per cow submitted to reproduction was less for cows in the G0% to 19% (191.1 kg) and G81% to 100 (181.8 kg) compared with cows in the G21% to 34 (197.0 kg), G38 (195.9 kg), G41% to 59 (199.7), and G63% to 78 (196.2). Cows in the G81% to 100% were the least productive. Thus, a proportion of Brahman genetics between 21% and 78% ensured superior productivity of Brahman-Angus cows subjected to subtropical conditions.

Randomized comparison between a forced air system and warm water bath for resuscitation of neonatal hypothermic calves with or without oral administration of caffeine

BACKGROUND

Hypothermia is a cause of neonatal calf death in cold climates. Practical and effective rewarming methods are important for bovine health within affected regions.

HYPOTHESIS/OBJECTIVES

To compare the rewarming rate and blood analytes (glucose, lactate, and cortisol) of calves resuscitated with forced air with warm water bath, with or without oral administration of caffeine.

ANIMALS

Twenty healthy neonatal Holstein bull calves.

METHODS

In this randomized, prospective study, calves born healthy and without history of dystocia were cooled to 32°C rectal temperature then thermally resuscitated using either forced air rewarming or warm water bath (40°C) with or without oral administration of caffeine. Rectal temperatures were used to quantify recovery rate. Measurements of glucose, lactate, and cortisol were recorded for every 2°C change in rectal temperature.

RESULTS

Rectal temperature decline (0.03°C per minute) and total cooling time (191.0 ± 33.3 minutes) did not significantly differ among treatment groups. Calves were successfully resuscitated to 38°C by either method. Time required to euthermia using warm water was significantly faster (0.1°C per minute; 64.3 ± 17.8 minute; P < .05) than forced air (0.05°C per minute; 123.1 ± 20.0 minutes). Caffeine had no significant effect on resuscitation rate (P = .14; 95% CI, -0.002 to 0.024) in either treatment; however, caffeine was associated with reduced time to euthermia by 8.3 and 10.8 minutes, respectively. Changes in metabolic variables (glucose, lactate, and cortisol), were inversely related to rectal temperature with no statistical significance among rewarming methods.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although warm water submersion is faster, forced air rewarming is an effective alternative for restoration of euthermia.

Comparison of behavior, thermoregulation, and growth of pair-housed versus individually housed calves in outdoor hutches during continental wintertime

Cold stress negatively affects the welfare of calves in outdoor hutches. No studies have examined the potential benefits of pair housing calves to buffer against cold stress. Our study evaluated the effects of pair versus individual housing on thermoregulatory, behavioral, and growth performance responses of calves in outdoor hutches during a Wisconsin continental winter. Forty-eight Holstein-Friesian heifer calves were enrolled into 1 of 2 housing treatments: individually (n = 16 calves) or pair housed (n = 16 pairs; 32 calves). Calves were fed milk twice daily, with ad libitum access to starter and water. Step-down weaning began on d 42 of life, and all milk was removed on d 54. Data collection continued through d 59. Calves were restricted inside a hutch (pair-housed calves in the same hutch) for 1 h during wk 4, 6, and 9 of life; internal hutch air temperature (T) was recorded with data loggers, and rectal temperature (RT) was recorded outside the hutch before and after restriction. On the subsequent 3 d in those weeks, calves' locations (outside or inside a hutch) were recorded at 15-min intervals using time-lapse cameras. Linear mixed models (change in T and RT after 1 h) and generalized linear mixed models with a β distribution (proportion of time spent inside hutches) were used to evaluate the fixed effects of housing treatment, week of life, and their interaction. For pair-housed calves, preference to be together was evaluated using one-sample t-tests comparing the proportion of time they were observed in the same location against 50% (chance, no preference), separately for each week of life. Predicted dry matter intake (DMI) of starter and body weight (BW) were standardized by day of life using regression models and used to calculate average daily gain (ADG) and feed conversion ratio (FCR; DMI of starter/ADG). Linear mixed models were constructed for each measure, separately for the preweaning, weaning, and postweaning periods, with a fixed effect of housing treatment; the models for BW included birth weight as a covariate. All mixed models included a random term for housing unit (individual or pair of calves) nested within treatment. Hutch T increased more after 1 h with pair-housed calves inside than with those housed individually (+2.3 vs. 1.4°C, respectively; standard error of the mean = 0.26°C). However, no treatment differences were detected in RT. Individually housed calves spent more time inside the hutches than pair-housed ones (93.9 vs. 90.7% of total time, respectively; standard error of the mean = 0.8%), and the latter chose to be together most of the time, regardless of location (90.0 ± 1.3%, 88.6 ± 1.2%, and 79.4 ± 4.2% in wk 4, 6, and 9 of life, respectively). After weaning, there was some evidence suggesting that pair-housed calves had greater starter DMI than those housed individually. No effects of housing type were found on FCR, BW, or ADG. Our study is the first to explicitly examine the potential benefits of pair housing for alleviating cold stress in outdoor-housed dairy calves, and we found limited evidence in support of our hypotheses.

Strategies and Mechanisms of Thermal Compensation in Newborn Water Buffaloes

Hypothermia is one of the principal causes of perinatal mortality in water buffaloes and can range from 3% to 17.9%. In ruminants, factors affecting hypothermia in newborns may be of intrinsic (e.g., level of neurodevelopment, birth weight, vitality score, amount of brown fat, skin features) or extrinsic origin (e.g., maternal care, environmental conditions, colostrum consumption). When newborn buffaloes are exposed to cold stress, thermoregulatory mechanisms such as peripheral vasoconstriction and shivering and non-shivering thermogenesis are activated to prevent hypothermia. Due to the properties of infrared thermography (IRT), as a technique that detects vasomotor changes triggered by a reduction in body temperature, evaluating the central and peripheral regions in newborn buffaloes is possible. This review aims to analyze behavioral, physiological, and morphological strategies and colostrum consumption as thermal compensation mechanisms in newborn water buffalo to cope with environmental changes affecting thermoneutrality. In addition, the importance of monitoring by IRT to identify hypothermia states will be highlighted. Going deeper into these topics related to the water buffalo is essential because, in recent years, this species has become more popular and is being bred in more geographic areas.

Vitality in Newborn Farm Animals: Adverse Factors, Physiological Responses, Pharmacological Therapies, and Physical Methods to Increase Neonate Vigor

Vitality is the vigor newborn animals exhibit during the first hours of life. It can be assessed by a numerical score, in which variables, such as heart rate, respiratory rate, mucous membranes' coloration, time the offspring took to stand up, and meconium staining, are monitored. Vitality can be affected by several factors, and therapies are used to increase it. This manuscript aims to review and analyze pharmacological and physical therapies used to increase vitality in newborn farm animals, as well as to understand the factors affecting this vitality, such as hypoxia, depletion of glycogen, birth weight, dystocia, neurodevelopment, hypothermia, and finally, the physiological mechanism to achieve thermostability. It has been concluded that assessing vitality immediately after birth is essential to determine the newborn's health and identify those that need medical intervention to minimize the deleterious effect of intrapartum asphyxia. Vitality assessment should be conducted by trained personnel and adequate equipment. Evaluating vitality could reduce long-term neonatal morbidity and mortality in domestic animals, even if it is sometimes difficult with the current organization of some farms. This review highlights the importance of increasing the number of stock people during the expected days of parturitions to reduce long-term neonatal morbidity and mortality, and thus, improve the farm's performance.

Effect of customised supplement on haemato-biochemical profile, serum minerals, metabolic hormones, antioxidant capacity and gene expression in crossbred calves

Present experiment examined the supplementary effect of a tailor-made supplement to farmers’-based diet in crossbred calves. Male crossbred calves (15) were randomly allocated in 3 dietary treatments consisting of 5 calves in each. The dietary treatments were: Control- cereal straw-based diet with concentrate mixture as per the farmers’ practices; CS (customised supplement)- control diet with additional customised supplement @ 0.25% of BW; SD-standard diet. Serum glucose was higher in SD than control, however, CS had an intermediate response. The serum macro (Ca and i-P) and trace (Zn, Cu, Fe and Mn) minerals were higher in SD and CS than control. The serum T3 and T4 hormones were significantly higher in SD and CS than control group. The serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were significantly higher in SD than control groups, however, SD had an intermediate position. The total antioxidant capacity (TAOC) was significantly higher in SD and CS than control group. The relative mRNA expression of cytokines, viz. IL-2 and IL-4 was significantly higher in SD and CS than control group. The relative mRNA expression of leptin (LEP) was significantly higher and ghrelin (GHRL) was significantly lower in SD than control group, however, CS had a transitional position. Thus, it can be concluded that supplementation of the customised supplement (@ 0.25% BW) to farmers’-based diet significantly improved the serum glucose concentration, metabolic hormone profile, antioxidant capacity and relative mRNA expression of cytokines and genes involved in energy metabolism in crossbred calves.

Maternal nutrient restriction during late gestation reduces vigor and alters blood chemistry and hematology in neonatal beef calves

Fall-calving primiparous beef females [body weight: 451 ± 28 (SD) kg; body condition score: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to parturition. Calves were reared naturally by their dams and monitored for latency times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores were assigned at 2, 5, 10, and 20 min of age. Rectal temperatures and jugular blood were obtained at 0 (pre-suckling), 6, 12, 24, and 48 h of age, and blood chemistry, hematology, cortisol, and insulin were determined. Data were analyzed with fixed effects of late gestational nutritional plane (single data point) or nutritional plane, hour, and their interaction (data over time, repeated measures). Calving date was a fixed effect; calf sex was included when P < 0.25. We previously reported that late gestational nutritional plane did not affect gestation length or calf size at birth, but calving assistance and fetal malpresentation occurred more often in NR. Nutritional plane did not affect (P = 0.65) duration of parturition, but calves born to NR dams had slower times to attempt to stand (P = 0.09), slower times to stand (P = 0.02), and poorer 20 min vigor scores (P = 0.05). Serum immunoglobulin G and A concentrations at 48 h were greater (P ≤ 0.03) for NR calves. Rectal temperature of NR calves was less (P = 0.02) at 0 h, but greater (P = 0.04) at 24 h compared with CON. Circulating glucose, non-esterified fatty acids, triglycerides, cortisol, and insulin were not affected by nutritional plane (P ≥ 0.18). Total protein and globulin from 6 to 48 h were greater (P ≤ 0.02) in NR calves. Calves from NR dams had greater (P ≤ 0.08) gamma-glutamyl transferase at 6, 12, and 48 h. Serum aspartate aminotransferase was greater (P ≤ 0.07) from 0 to 24 h and creatine kinase was greater (P ≤ 0.04) from 6 to 24 h in NR calves. At 0 h, potassium was greater (P = 0.03) in NR calves. Calves born to CON had greater chloride (P = 0.08; main effect), sodium (P ≤ 0.09) from 0 to 48 h, and anion gap (P = 0.02) at 6 h. Hematocrit from 6 to 24 h and red blood cells and hemoglobin at 6 and 12 h were greater (P ≤ 0.09) in CON calves. These data indicate that nutrient restriction during late gestation resulted in less vigorous calves with more indicators of trauma in early life.

The effect of birth weight and time of day on the thermal response of newborn water buffalo calves

During the 1st days of life, water buffalo calves, especially those with low birth weight, are susceptible to hypothermic mortality due to scarce energy reserves provided by fats. This means that monitoring the thermal state of newborns is essential. The objectives of the present study were to apply infrared thermography (IRT) in 109 buffalo calves to detect differences in the surface temperatures of six thermal windows -lacrimal gland, lacrimal caruncle, periocular region, nostrils, ear canal, pelvic limbs-, and determine their association to birth weight during the first 6 days of life. The calves were divided into four categories according to their weight (Q₁, 37.8-41.25 kg; Q₂, 41.3-46.3 kg; Q₃, 46.4-56.3 kg; Q₄, 56.4-60.3 kg). The thermographic images were recorded in the morning and afternoon. Results showed that the animals in Q₄ registered the highest temperatures in all the thermal windows, and that these were higher in the afternoon (p < 0.0001). When considering the thermal windows, those located in the facial region recorded the highest temperatures; in contrast, the temperatures at the pelvic limbs remained below the average values of the other windows (33.41 and 33.76°C in the morning and afternoon, respectively). According to these results, the birth weight of water buffaloes is a factor that alters their thermoregulation during the 1st days of life, a condition that can be partially compensated by colostrum intake to promote development of an efficient thermoregulatory mechanism in water buffalo calves.

Effects of spring- versus fall-calving on perinatal nutrient availability and neonatal vigor in beef cattle

To determine the effect of calving season on perinatal nutrient availability and neonatal beef calf vigor, data were collected from 4 spring- (average calving date: February 14; n = 203 total) and 4 fall- (average calving date: September 20; n = 179 total) calving experiments. Time to stand was determined as minutes from birth to standing for 5 s. After birth, calf weight and size (length, heart and abdominal girth, and cannon circumference) were recorded. Jugular blood samples and rectal temperatures were obtained at 0, 6, 12, and 24 h postnatally in 6 experiments and at 48 h postnatally in Exp. 2 to 8. Data were analyzed with fixed effects of season (single point) or season, hour, and their interaction (over time, using repeated measures). Experiment was a random effect; calf sex was included when P ≤ 0.25. Within calving season, correlations were determined between calf size, vigor, and 48-h serum total protein. Fall-born calves tended to have lighter (P = 0.09) birth weight and faster (P = 0.05) time to stand than spring-born calves. Season did not affect (P ≥ 0.18) gestation length, other calf size measures, or 48-h serum total protein. Fall-born calves had greater (P ≤ 0.003) rectal temperature at 0, 24, and 48 h postnatal. Spring-born calves had greater (P ≤ 0.009) circulating glucose at 0 h, serum non-esterified fatty acids at 0 and 6 h, and plasma triglycerides at 0, 6, 12, and 48 h. Fall-born calves had greater (P ≤ 0.03) sodium from 6 to 48 h and magnesium from 0 to 24 h of age. Phosphorus was greater (P ≤ 0.02) at 6 and 12 h of age in spring-born calves. Spring-born calves had greater (P ≤ 0.04) aspartate aminotransferase at 12 and 24 h and creatine kinase at 0 and 12 h of age. Fall-born calves had greater (P ≤ 0.03) albumin, calcium, and chloride, had lower (P ≤ 0.03) bicarbonate and direct bilirubin, and tended to have greater (P = 0.10) anion gap (all main effects of calving season). Calf birth weight had a weak positive relationship (P ≤ 0.03) with 48-h serum total protein and time to stand in fall-born, but not spring-born, calves. Overall, fetal growth was restricted and neonatal dehydration was increased by warm conditions for fall-born calves, but vigor and metabolism were negatively affected by cold conditions in spring-born calves. These data suggest that calving season influences perinatal nutrient availability, which may impact the transition of beef calves to postnatal life.

Integrated Analysis of Transcriptome, microRNAs, and Chromatin Accessibility Revealed Potential Early B-Cell Factor1-Regulated Transcriptional Networks during the Early Development of Fetal Brown Adipose Tissues in Rabbits

In domestic mammals, cold stress decreases the survival rate of newborns and increases the cost of management. Brown adipose tissue (BAT) is the main thermogenic organ for cubs, and well-developed fetal BAT (FBAT) is beneficial for newborns to maintain core temperatures during the first several days of life. However, our knowledge of the epigenetic mechanisms during the early development of FBAT remains largely unknown. Rabbits (Oryctolagus cuniculus) are economically important domestic animals. In this study, a histological analysis shows that the tissue content, thermogenic capacity, and lipid content of FBAT dramatically increases from gestational day 21 (G21) to gestational day 24 (G24) in rabbits. RNA-seq, microRNA-seq (miRNA-seq), and the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) show that many genes, miRNAs, and chromatin-accessible regions (referred to as peaks) were identified as significantly changed from G21 to G24, respectively. The upregulated genes from G21 to G24 were significantly enriched in the mitochondrial metabolism and thermogenesis-related signal pathways. The integrated analysis of transcriptome and chromatin accessibility reveals that the peaks in the promoters have a more regulatory effect than peaks in other genomic elements on the expression of their nearby genes in FBATs. The upregulated genes that are associated with increased chromatin accessibility in the promoter regions are involved in the energy metabolism-related signaling pathways. The genes that have a greater tendency to be regulated by miRNAs than the chromatin accessibility in gene promoters are involved in the apelin, insulin, and endocytosis signaling pathways. Furthermore, genome-wide transcription factor (TF) footprinting analysis identifies early B-cell factor1 (EBF1) as playing a key role during early FBAT development. The carbon metabolism, citrate cycle, and PPAR signaling pathways are significantly enriched by the predicted EBF1-regulated cascade TF-network. In conclusion, our work provides a framework for understanding epigenetics regulatory mechanisms underlying the early development of FBAT and identifies potential TF involved in the early development of FBAT in rabbits.

Neonatal infrared thermography images in the hypothermic ruminant model: Anatomical-morphological-physiological aspects and mechanisms for thermoregulation

Hypothermia is one factor associated with mortality in newborn ruminants due to the drastic temperature change upon exposure to the extrauterine environment in the first hours after birth. Ruminants are precocial whose mechanisms for generating heat or preventing heat loss involve genetic characteristics, the degree of neurodevelopment at birth and environmental aspects. These elements combine to form a more efficient mechanism than those found in altricial species. Although the degree of neurodevelopment is an important advantage for these species, their greater mobility helps them to search for the udder and consume colostrum after birth. However, anatomical differences such as the distribution of adipose tissue or the presence of type II muscle fibers could lead to the understanding that these species use their energy resources more efficiently for heat production. The introduction of unconventional ruminant species, such as the water buffalo, has led to rethinking other characteristics like the skin thickness or the coat type that could intervene in the thermoregulation capacity of the newborn. Implementing tools to analyze species-specific characteristics that help prevent a critical decline in temperature is deemed a fundamental strategy for avoiding the adverse effects of a compromised thermoregulatory function. Although thermography is a non-invasive method to assess superficial temperature in several non-human animal species, in newborn ruminants there is limited information about its application, making it necessary to discuss the usefulness of this tool. This review aims to analyze the effects of hypothermia in newborn ruminants, their thermoregulation mechanisms that compensate for this condition, and the application of infrared thermography (IRT) to identify cases with hypothermia.

Strategies for Hypothermia Compensation in Altricial and Precocial Newborn Mammals and Their Monitoring by Infrared Thermography

Thermoregulation in newborn mammals is an essential species-specific mechanism of the nervous system that contributes to their survival during the first hours and days of their life. When exposed to cold weather, which is a risk factor associated with mortality in neonates, pathways such as the hypothalamic–pituitary–adrenal axis (HPA) are activated to achieve temperature control, increasing the circulating levels of catecholamine and cortisol. Consequently, alterations in blood circulation and mechanisms to produce or to retain heat (e.g., vasoconstriction, piloerection, shivering, brown adipocyte tissue activation, and huddling) begin to prevent hypothermia. This study aimed to discuss the mechanisms of thermoregulation in newborn domestic mammals, highlighting the differences between altricial and precocial species. The processes that employ brown adipocyte tissue, shivering, thermoregulatory behaviors, and dermal vasomotor control will be analyzed to understand the physiology and the importance of implementing techniques to promote thermoregulation and survival in the critical post-birth period of mammals. Also, infrared thermography as a helpful method to perform thermal measurements without animal interactions does not affect these parameters.

Venous blood gas parameters in healthy Mediterranean buffalo calves in the first 72 hours of life

In the first hours after calving the neonate radically modifies its anatomy and physiology to adapt to extrauterine life. These modifications, however, make the calf prone to respiratory and metabolic dysfunction. Thus, stillbirth, defined as the death of the neonate within 48 h after birth, represents a relevant issue for buffalo farming. Of the clinical procedures, the blood gas analysis of venous samples provides useful information regarding the acid-base status of the neonate, allowing the optimal management of potential illness calves. However, the blood gas parameters have never been studied in the buffalo calf in the first 72 h of life. Thus, this study aimed to report blood gas parameters at calving and 1, 12, 24, and 72 h after birth in healthy buffalo neonates born after normal parturition. The study involved 20 healthy buffalo calves, born from normal pregnancy and parturition. The parturition and the first hours after were monitored by closed-circuit television cameras, and within 1 min after calving the buffalo neonate received a clinical evaluation (APGAR, temperature), venous blood sampling for blood gas (pH, partial pressure carbon dioxide - pCO₂, partial pressure oxygen - pO₂, base excess, bicarbonate concentration, oxygen saturation, total carbon dioxide - tCO₂, and lactate), and glycemia analysis. The same evaluations were performed after 1, 12, 24, and 72 h. The present study showed a moderate mixed acidosis at calving, similar to that reported in the bovine neonate, likely due to the high venous blood pCO₂ and lactate. This acidemia resolved spontaneously within 12 h as a reduction of pCO₂ (P ≤ 0.05). Lactate reduced significantly (P ≤ 0.05) only at 72 h, similarly to the trend reported previously for the bovine calf. Blood lactate concentration was correlated with glycemia at calving and 1 h (r = 0.677, P = 0.014), and with stage 2 duration (r = 0.647, P = 0.006). These findings support a possible mechanism of glucose generation induced by catecholamines coupled to anaerobic metabolism soon after calving. After calving, all the blood gas parameters changed rapidly reaching values comparable with those reported in the literature for older buffalo calves from 72 h after calving. No correlations were found between APGAR score and venous blood gas parameters, likely due to the inclusion criteria that selected only health buffalo calves born after normal parturition. The findings suggested that the venous blood gas analysis could be considered supportive rather than an alternative to the clinical evaluation of the buffalo calf.

Relationships of retained energy and retained protein that influence the determination of cattle requirements of energy and protein using the California Net Energy System

Interrelationships between retained energy (RE) and retained protein (RP) that are essential in determining the efficiency of use of feeds and the assessment of energy and protein requirements of growing cattle were analyzed. Two concerns were identified. The first concern was the conundrum of a satisfactory correlation between observed and predicted RE (r = 0.93) or between observed and predicted RP when using predicted RE to estimate RP (r = 0.939), but a much lower correlation between observed and predicted RP when using observed RE to estimate RP (r = 0.679). The higher correlation when using predicted vs. observed RE is a concern because it indicates an interdependency between predicted RP and predicted RE that is needed to predict RP with a higher precision. These internal offsetting errors create an apparent overall adequacy of nutrition modeling that is elusive, thus potentially destabilizing the predictability of nutrition models when submodels are changed independently. In part, the unsatisfactory prediction of RP from observed RE might be related to the fact that body fat has a caloric value that is 1.65 times greater than body protein and the body deposition of fat increases exponentially as an animal matures, whereas body deposition of protein tends to plateau. Thus, body fat is more influential than body protein in determining RE, and inaccuracies in measuring body protein will be reflected in the RP comparison but suppressed in the RE calculation. The second concern is related to the disconnection when predicting partial efficiency of use of metabolizable energy for growth (kG) using the proportion of RE deposited as protein-carcass approach-vs. using the concentration of metabolizable energy of the diet-diet approach. The culprit of this disconnection might be related to how energy losses that are associated with supporting energy-expending processes (HiEv) are allocated between these approaches. When computing kG, the diet approach likely assigns the HiEv to the RE pool, whereas the carcass approach ignores the HiEV, assigning it to the overall heat production that is used to support the tissue metabolism. Opportunities exist for improving the California Net Energy System regarding the relationships of RE and RP in computing the requirements for energy and protein by growing cattle, but procedural changes might be needed such as increased accuracy in the determination of body composition and better partitioning of energy.

Sensitivity, Impact and Consequences of Changes in Respiratory Rate During Thermoregulation in Livestock – A Review

This review discusses the thermal conservative and heat dissipating roles of one of the most sensitive thermoregulatory variables (respiratory rate) with the aim of enhancing its application in evaluating both cold and heat adaptation. During cold exposure, livestock enhance the economy of body heat through reduction in respiratory rate with the extent of reduction being greater and commencing at relatively higher ambient temperature in poorly adapted phenotypes. This is accompanied by an increase in tidal volume and alveolar oxygen uptake, but a decrease in partial pressure of oxygen. On the other hand, heat stress induces increase in respiratory rate to enhance evaporative heat loss with the magnitude of such increase being greater and commencing at relatively lower ambient temperature in phenotypes that are poorly-adapted to heat. This is accompanied by a decrease in tidal volume and the development of hypocapnia. The increase in respiratory rate is observed to be greater, moderate and lesser in livestock that are mainly (pigs, rabbits and poultry), moderately (sheep, goats and Bos taurus) and less (Zebu cattle) dependent on respiratory evaporative heat loss, respectively. The changes during chronic heat stress may cause acid-base crisis in all livestock, in addition to reduction in eggshell quality in birds; due to marked decrease in partial pressure of carbon dioxide and a compensatory increase in elimination of bicarbonate. Within and between breed variations in sensitivity of respiratory rhythm to both cold and heat stress has shown high applicability in identifying phenotypes that are more susceptible to thermal stress; with some cellular and metabolic changes occurring to protect the animal from the consequences of hypo- or hyper-thermia. The information in this review may provide basis for identification of genes that support or suppress thermoregulation and may also be of great use in animal breeding, genomics and selective thermal stress mitigation to provide maximum protection and comfort to poorly-adapted phenotypes.

Oxidative stress in neonatology: a review

Free radicals are highly reactive oxidizing agents containing one or more unpaired electrons. Both in human and veterinary neonathology, it is generally accepted that oxidative stress functions as an important catalysator of neonatal disease. Soon after birth, many sudden physiological and environmental conditions make the newborn vulnerable for the negative effects of oxidative stress, which potentially can impair neonatal vitality. As a clinician, it is important to have in depth knowledge about factors affecting maternal/neonatal oxidative status and the cascades of events that enrol when the neonate is subjected to oxidative stress. This report aims at providing clinicians with an up-to-date review about oxidative stress in neonates across animal species. It will be emphasized which handlings and treatments that are applied during neonatal care or resuscitation can actually impose oxidative stress upon the neonate. Views and opinions about maternal and/or neonatal antioxydative therapy will be shared.

Scientific Opinion on the welfare of cattle kept for beef production and the welfare in intensive calf farming systems

Information given in previous Opinions "Welfare of cattle kept for beef production" (SCAHAW, 2001) and "The risks of poor welfare in intensive calf farming systems" (EFSA, 2006) is updated and recent scientific evidence on the topics reviewed. Risks of poor welfare are identified using a structured analysis, and issues not identified in the SCAHAW (2001) beef Opinion, especially effects of housing and management on enteric and respiratory diseases are reviewed. The Opinion covers all systems of beef production, although the welfare of suckler cows or breeding bulls is not considered. The Chapter on beef cattle presents new evidence and recommendations in relation to heat and cold stress, mutilations and pain management, digestive disorders linked to high concentrate feeds and respiratory disorders linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment. Major welfare problems in cattle kept for beef production, as identified by risk assessment, were respiratory diseases linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment, digestive disorders linked to intensive concentrate feeding, lack of physically effective fibre in the diet, and behavioural disorders linked to inadequate floor space, and co-mingling in the feedlot. Major hazards for white veal calves were considered to be iron-deficiency anaemia, a direct consequence of dietary iron restriction, enteric diseases linked to high intakes of liquid feed and inadequate intake of physically effective fibre, discomfort and behavioural disorders linked to inadequate floors and floor space.

Test systems to study the structure and function of uncoupling protein 1: a critical overview

The discovery of active brown adipose tissue (BAT) in healthy adult humans has renewed interest in the biology of this organ. BAT is capable of distributing nutrient energy in the form of heat allowing small mammals to efficiently defend their body temperature when acutely exposed to the cold. On the other hand BAT might be a target for the treatment of obesity and related diseases, as its pharmacological activation could allow release of excess energy stored in white adipose tissue depots. Energy dissipation in BAT depends on the activity of uncoupling protein 1 (UCP1), therefore a BAT-based obesity therapy requires a detailed understanding of structure and function of UCP1. Although UCP1 has been in the focus of research since its discovery, central questions concerning its mechanistic function and regulation are not yet resolved. They have been addressed in native mitochondria but also in several test systems, which are generally used to lower inter-experimental variability and to simplify analysis conditions. Different test systems have contributed to our current knowledge about UCP1 but of course all of them have certain limitations. We here provide an overview about research on UCP1 structure and function in test systems. So far, these have nearly exclusively been employed to study rodent and not human UCP1. Considering that the amino acid sequence of mouse and human UCP1 is only 79% identical, it will be essential to test whether the human version has a similarly high catalytic activity, allowing a relevant amount of energy dissipation in human BAT. Besides the issue of comparable mechanistic function a sufficiently high expression level of human UCP1 is a further prerequisite for anti-obesity therapeutic potential. Treatments which induce BAT hyperplasia and UCP1 expression in humans might therefore be equally important to discover as mere activators of the thermogenic process.

Adipocyte metabolism and cellularity are related to differences in adipose tissue maturity between Holstein and Charolais or Blond d'Aquitaine fetuses

This paper reports the metabolic and morphological characteristics of bovine adipose tissue (AT) at end of fetal life and its variability with breed and anatomical site of AT. Our hypothesis was that, in cattle, end-of-fetal-life differences in adipocyte number, size, and histology may account for differences in AT maturity. To address this question, perirenal and intermuscular AT were sampled from Charolais, Blond d'Aquitaine, and Holstein fetuses at 260 d postconception. Holstein fetuses showed greater leptin mRNA abundance, which is consistent with the greater perirenal AT weight (P = 0.03) than Blond d'Aquitaine fetuses. Compared with Blond d'Aquitaine or Charolais fetuses, Holstein fetuses had larger (P < 0.001) adipocytes, greater (P < 0.05) activities of enzymes involved in de novo fatty acid (FA) synthesis (FA synthase, glucose-6-phosphate dehydrogenase, malic enzyme) and FA esterification (glycerol-3-phosphate dehydrogenase), and greater (P = 0.06, P = 0.10, P < 0.001) mRNA abundance for lipolytic enzymes (hormone-sensitive lipase and adipose triglyceride lipase) and uncoupling protein 1 in both perirenal and intermuscular AT. This indicates increased FA turnover in Holstein adipocytes through FA storage, mobilization, and oxidation pathways. Whatever the breed, adipocytes were smaller in perirenal AT than intermuscular AT. Whatever the breed or anatomical site, bovine AT at 260 d postconception contained predominantly unilocular adipocytes believed to be white adipocytes together with a few multilocular brown adipocytes. We conclude that the greater metabolic and morphologic maturity of adipocytes from Holstein than Blond d'Aquitaine and Charolais fetuses may contribute to the greater thermogenic aptitude of Holstein newborns. Moreover, the presence of both white and brown adipocytes at the end of fetal life highlights the complexity of AT structure and may indicate that the cellular and functional heterogeneity of AT repeatedly observed postnatally has a developmental origin.

Resuscitation and critical care of neonatal calves

Neonatal morbidity and mortality are major economic concerns in both beef and dairy cattle in the United States. In both beef and dairy most calf death occurs in the early neonatal period, particularly in calves born following dystocia. This article focuses on the resuscitation of calves after delivery and highlights some therapeutic points for the care of critical calves.

Perinatal physiology in cloned and normal calves: physical and clinical characteristics

The period immediately after birth is a vital time for all newborn calves as the cardiovascular, respiratory, and other organ systems adapt to life ex utero. Reported neonatal mortality rates suggest this period to be especially critical in cloned calves; yet prospective, controlled studies on the physiological status of these calves are lacking. The objectives of this study were to compare neonatal (birth to 48 h of age) physical and clinical characteristics and placental morphology of cloned and embryo transfer control calves delivered by cesarean section after induced labor. All calves were raised under specialized neonatal-care protocols at a large-animal veterinary research and teaching hospital. Cloned calves were similar to controls for many parameters studied. Notable exceptions included developmental delays of important physical adjustment parameters and enlargement of the umbilical region. Placentas associated with cloned calves contained fewer total placentomes, a twofold increase in surface area and mass per placentome, and a shift in placentome morphology toward larger, flatter placentomes. The most striking clinical variations detected in clones were hypoglycemia and hyperfructosemia, both measures of carbohydrate metabolism. Because the placenta is known to be the source of plasma fructose in newborn calves, increased fructose production by the cloned placenta may be an important factor in the etiology of umbilical and cardiac anomalies in clones observed in this and other studies.

Impacts of Dystocia on Health and Survival of Dairy Calves

The objectives of this study were to determine incidence of stillbirths and heifer-calf morbidity and mortality, and their association with dystocia on 3 Colorado dairies. A total of 7,380 calvings produced 7,788 calves on 3 Colorado dairy operations between October 1, 2001, and November 5, 2002. Dystocia score and calf status (alive vs. dead) were recorded at calving. Calves that were born alive, but died before 24 h of age, also were recorded as stillborn. Heifer calves were monitored for 120 d to evaluate morbidity and mortality. More than half (51.2%) of calves born to primiparous dams, compared with 29.4% of calves born to multiparous dams, required assistance during calving. A larger percentage of bull calves (40.0%) required assistance compared with heifer calves (33.0%). Proportion of stillborn calves was 8.2% overall, with bull calves, twin calves, calves born to primiparous dams, and those born to dams having dystocia having a larger stillbirth percentage compared with heifer calves, singletons, calves born to multiparous dams, and unassisted calvings, respectively. Multiple logistic regression models were constructed to evaluate stillbirths and heifer health while accounting for the clustering of calves within dairy. The models included dystocia score, parity, and season of calving as explanatory variables for heifer events and also calf gender, and single or twin birth for the stillbirth models. Heifer calves born to dams having severe dystocia had greater odds of stillbirth [odds ratio (OR) = 20.7] and treatment of respiratory disease (OR = 1.7), digestive disease (OR = 1.3), and overall heifer mortality (OR = 6.7). Calf gender and dam parity interacted with calving ease to affect stillbirths. For calves having severe dystocia, heifer calves and calves born to multiparous dams were at increased risk of stillbirth compared with bull calves and calves born to primiparous dams, respectively. Survival analysis demonstrated that severe dystocia was associated with stillbirths and deaths up to 30 d of age. Relatively simple interventions have the potential to significantly reduce the impact of dystocia on calf mortality and morbidity on dairy farms. Education of farm management and personnel in strategies to reduce dystocia and its effect on calf health should be a priority according to the results of this study.

Neonatal adjustments

Pharmacodynamic responses by neonates are the same as those for adults, but physiologic differences and pathophysiologic changes can affect pharmacokinetic values sufficiently to require adjustments in dosage regimens used for calves. Adjunctive care may be necessary for some patients to correct or maintain perfusion and temperature of tissues so that absorption and distribution may be adequate. Intravenous administration may be the only route appropriate for some critically ill patients. Anatomic sites and formulation of products administered by extravascular parenteral routes markedly can affect absorption of those products and subsequent clinical response to treatment.

Optimal timing of elective caesarean section in Belgian White and Blue breed of cattle: the calf's point of view

The purpose of this study was to evaluate whether the timing of elective caesarean section (ECS) during parturition affects pulmonary and metabolic adaptation to extra-uterine life in healthy Belgian White and Blue (BWB) calves delivered at term. Vaginal palpation was performed and deliveries divided into six categories of timing for ECS: cervix closed (TECS 1); passive and active cervical dilatation (TECS 2 and TECS 3); full cervical dilatation (TECS 4); spontaneous rupture of allantoic (TECS 5) and amniotic (TECS 6) membranes. One hundred and eighteen BWB calves were examined at birth, 5, 15, 30, 45 and 60 min and 2, 3, 6, 12 and 24 h after birth using the following measurements: physical examination (time between birth and sternal recumbency [T-SR]); heart rate (mHR); arterial blood gas analyses (arterial partial pressure in oxygen [PaO(2)], in carbon dioxide [PaCO(2)], arterial haemoglobin oxygen saturation [SaO(2)], alveolo-arterial difference in oxygen [AaDO(2)]); pulmonary function tests using the oesophageal balloon catheter technique (respiratory rate [RR], total pulmonary resistance [R(L)], dynamic lung compliance [C(Ldyn)], tidal volume [V(T)] and minute volume [V(E)]); arterial and venous blood acid-base balance analyses (arterial and venous pH [pHa and pHv], bicarbonate concentration [HCO(3)a and HCO(3)v], base excess [BEa and BEv]); rectal temperature (RT); jugular venous blood sampling for determination of metabolic variables (blood glucose [G], plasma lactate [L], serum cortisol [C], plasma noradrenaline [NA] and adrenaline [A] concentrations); haematological variables (red blood cell count [RBC], total haemoglobin concentration [Hb], Packed Cell Volume [PCV]) and passive immune transfer variables (total serum protein [TP] and beta(2)gammaglobulin [beta(2)gamma] concentrations).TECS significantly (P</=0.05) influenced PaO(2), SaO(2), AaDO(2), RR, V(T), V(E), C(Ldyn), RT, G, NA, A, RBC, Hb and TP: compared to TECS> or =4 calves, TECS< or =3 calves showed lower PaO(2), SaO(2), V(T), C(Ldyn), RT, G, NA, A, RBC, Hb and TP and higher AaDO(2), RR, V(E). TECS differences progressively decreased and disappeared between 6 and 12 h after birth in TECS 2 and 3 calves but remained up to 24 h in TECS 1 calves. Improved postnatal respiratory and metabolic adaptation in TECS> or =4 calves were mainly related to differences in exposure to labour and subsequent hormonal surge: catecholamines, particularly A, enabled more effective removal of lung liquid and/or release of surfactant which contribute to better gas exchanges and induced greater energy mobilization to maintain adequate body temperature. It was concluded waiting for full cervical dilatation before performing CS should be encouraged because it promotes postnatal respiratory and metabolic adaptation in full-term BWB calves.

Effect of three resuscitation procedures on respiratory and metabolic adaptation to extra uterine life in newborn calves

The purpose of this study was to evaluate the effects of three resuscitation procedures on respiratory and metabolic adaptation to extra-uterine life during the first 24 h after birth in healthy newborn calves. Twenty-four newborn calves were randomly grouped into four categories: six calves did not receive any specific resuscitation procedure and were considered as controls (C); six received pharyngeal and nasal suctioning immediately after birth by use of a hand-powered vacuum pump (SUC); six received five litres of cold water poured over their heads immediately after birth (CW) and six were housed in a calf pen with an infrared radiant heater for 24 h after birth (IR). Calves were examined at birth, 5, 15, 30, 45 and 60 min, 2, 3, 6, 12 and 24 h after birth and the following measurements were recorded: physical and clinical examination, arterial blood gas analysis, pulmonary function tests using the oesophageal balloon catheter technique, arterial and venous blood acid-base balance analysis, jugular venous blood sampling for determination of metabolic, haematological and passive immune transfer variables. SUC was accompanied by improved pulmonary function efficiency and by a less pronounced decrease in body temperature. The "head shaking movement" and the subsequent temporary increase in total pulmonary resistance as well as the greater lactic acidosis due to CW were accompanied by more efficient, but statistically non-significant, pulmonary gas exchanges. IR allowed maintenance of higher body temperature without requiring increased catabolism of energetic stores. IR also caused a change in breathing pattern which contributed to better distribution of the ventilation and to slightly improved gas exchange. The results indicate that use of SUC, CW and IR modified respiratory and metabolic adaptation during the first 24 h after birth without side-effects. These resuscitation procedures should be recommended for their specific indication, i.e. cleansing of fetal fluid from upper airways, hypothermal stimulation of breathing and prevention of heat losses.

Risk factors for high herd level calf morbidity risk from birth to weaning in beef herds in the USA

We analyzed data from a national survey of beef cow-calf producers in the USA to quantify the effects of hypothesized risk factors on herd-level calf morbidity risk from birth to weaning. The analysis included 2490 herds from 23 states. Two stepwise logistic regressions were fit to identify factors associated with &ge;10% morbidity. The first model included all herds dichotomized into high-morbidity herds with &ge;10% morbidity and low-morbidity herds with <10% morbidity. The second model excluded herds with between 5 and 10% morbidity, and compared >/=10% morbidity with </=5% morbidity. The risk of dystocia was categorized into five levels for analysis; all non-zero categories were associated with increased odds of being a high-morbidity herd compared to herds with no dystocia (OR=2.7-5.5). Having >70% of cows and heifers calves in confinement also increased the odds of being a high-morbidity herd (OR=1.8). The population attributable fractions for dystocia and confined calving for the model including all herds dichotomized at 10% morbidity were 0.41 and 0.11, respectively. The summary population attributable fraction for both factors was 0.46.

Prepartum protein restriction does not alter norepinephrine-induced thermogenesis or brown adipose tissue function in newborn calves

We examined the effect of prepartum protein restriction on thermogenesis and several aspects of perirenal (brown) adipose tissue (BAT) in newborn calves. Lipid synthesis and morphology also were compared between BAT and sternum (white) adipose tissue. During the last 140 d of gestation, heifers were fed isocaloric diets containing adequate (10.4%) or restricted (average of 6.8%, dry matter basis) levels of protein. Body condition scores and weight gain during gestation were significantly lower in heifers fed the restricted-protein diet. However, newborn calf birth weight, calf BAT weight and composition, and calf thermoneutral metabolic rates were not affected by prepartum protein restriction. Similarly, visceral organ weights, except for lung plus trachea, were not affected (P > 0.10) by prepartum protein treatment. Peak metabolic rates were not affected (P > 0.10) by prepartum protein treatment and on average were twice the thermoneutral metabolic rates. Consistent with this, BAT of calves from heifers fed adequate- or restricted-protein diets did not differ in lipid synthesis, cellularity, or uncoupling protein mRNA:28S rRNA ratios. Although both perirenal and sternum adipocytes were mostly unilocular, perirenal adipocytes contained numerous large mitochondria with well-differentiated cristae; sternum adipocytes contained a small number of mitochondria with poorly developed cristae. Fatty acid biosynthesis from acetate was high in BAT (55-57 nmol acetate incorporated.100 mg-1.h-1) but barely detectable in sternum adipose tissue. Conversely, fatty acid biosynthesis from glucose was 80-110% higher in sternum adipose tissue than in BAT (4.5 vs 2.1-2.5 nmol glucose incorporated.100 mg-1.h-1). Thus maternal protein restriction severely affected heifers but had no effect on neonatal calf thermogenesis or BAT function.