Partial herd hoof trimming results in a higher economic net benefit than whole herd hoof trimming in dairy herds.

Sole ulcers, a common cause of lameness is the costliest non-infectious foot lesion in dairy cows and one of the most prevalent non-infectious foot lesions in freestall housing systems. Costs associated with sole ulcers are treatment costs, plus increased labor and decreased productivity and fertility. Routine hoof trimming is part of a strategy to manage sole ulcers. However, hoof trimming strategies differ among farms. The two most frequently applied strategies are: 1) partial herd hoof trimming with a 2-month interval between trims; and 2) whole herd hoof trimming at 6-month intervals. A Markov model was developed to investigate whether every 2 months partial herd hoof trimming or whole herd hoof trimming every 6 months was the most cost-effective strategy to avoid costs associated with sole ulcers. In this model, the net benefits for a 100-cow herd and the average productive life span of a dairy cow in intensive dairy systems of 3 years were evaluated. Partial herd hoof trimming was the most cost-effective strategy 100% of the time compared to whole herd hoof trimming, with a difference in 3-year net benefits of US$4,337 (95% CI: US$2,713-US$5,830). Based on sensitivity analyses, variables that were the sources of the biggest uncertainty in the model were herd size, the probability of being trimmed in a partial herd trim, and the prevalence of sole ulcers. To further investigate the impacts of herd size and of probability of being trimmed, various scenario analyses were conducted. With increasing herd size, the difference in net benefits in favor of partial herd hoof trimming increased even more. Scenario analyses about the probability of getting trimmed all indicated that targeted intervention increased the difference in net benefits in favor of partial herd hoof trimming. However, if the selection of cows to be trimmed in a partial herd trim was random, the whole herd hoof trimming strategy became cost-effective. Therefore, targeted selection and early intervention are necessary to decrease costs associated with sole ulcers.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 1: Risk factors.

Maternal antibodies, delivered to the calf via colostrum, are crucial to prevent calfhood diseases and death. However, knowledge regarding the factors influencing this transfer of total and specific Immunoglobulin G (IgG) against common enteric and respiratory disease pathogens under current production conditions is sparse. The objectives of this study were to determine risk factors influencing total and pathogen-specific immunoglobulin G (IgG) concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus type 1 and 2 (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus type 1 (BHV-1) in the serum of newborn beef calves. A total of 420 serum samples were collected from 1- to 7-day-old beef calves born on 6 farms in Alberta, Canada. Samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against E. coli, BRoV, C. parvum, BVDV, PI-3, BRSV, and BHV-1. Multivariable multilevel linear and logistic regression models were built to evaluate dam- and calf-level risk factors associated with total and pathogen-specific IgG concentrations, failed transfer of passive immunity (FTPI; serum IgG < 10 g/L), and inadequate transfer of passive immunity (ITPI; serum IgG < 24 g/L). Farm was included as a random effect in all models to account for clustering at the herd level. Of the 420 calves included in this study, 5% (n = 20) and 18% (n = 75) of calves had FTPI and ITPI, respectively. Receiving colostrum intervention (i.e., being fed colostrum or colostrum product by either bottle or tube) was the most consistent risk factor for low total IgG concentration and significantly increased the odds of FTPI (Odds ratio (OR): 6.1, 95% CI: 2.0-18.9) and ITPI (OR: 4.8, 95% CI: 2.1-10.8). Calves born to cows consistently had higher pathogen-specific IgG concentrations (P < 0.0001), compared to calves born from heifers, and calves born to vaccinated dams had significantly higher BRoV, BVDV, and BHV-1-specific IgG concentrations. Interestingly, E.coli-specific IgG concentrations were associated with dam vaccination only in cows but not in heifers, which was likely due to differing vaccination strategies used. This study highlights the need to review and refine protocols with respect to dam vaccination and colostrum intervention on cow-calf operations.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 2: Associations with health and growth.

The association of poor transfer of passive immunity (TPI) with negative health outcomes is extensively researched in dairy calves. However, few field studies have examined the effect of total and particularly pathogen-specific Immunoglobulin G (IgG) concentrations on pre-weaning health and growth of beef calves. Hence, the objective of this study was to determine the association of total and pathogen-specific IgG concentrations against selected pathogens associated with neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) and the odds of pre-weaning treatments, mortality, and the growth of newborn beef calves. A total of 420 serum samples from 1- to 7-day old beef calves born on 6 farms in Alberta, Canada, were available for this observational study. Serum samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus Type 1 (BHV-1). Data about the individual dam- and calf-level risk factors, calf treatments, mortality, and birth and weaning weights were collected. Multivariable multilevel logistic and linear regression models were built to evaluate the association of total and pathogen-specific IgG concentrations with the odds of mortality and average daily gain (ADG), respectively, while their association with the odds of pre-weaning treatment was established by univariable logistic regression analysis. The odds of calves with IgG concentrations < 10 g/L of getting treated (OR 7.9, 95 % CI 2.7-23.7) and dying (OR: 18.5, 95 % CI: 3.7-93.4) were higher than for their counterparts (P < 0.0001). Calves with IgG concentrations < 24 g/L also had higher odds of dying (OR: 10.1, 95 % CI: 2.6-40.2) and had lower ADG (-0.09 kg, SE: 0.03, P < 0.002) than calves with IgG concentrations ≥ 24 g/L. Higher BVDV-specific IgG concentration was protective against mortality (OR: 0.97, 95 % CI: 0.96-0.99, P < 0.001). This study highlights the negative association of inadequate TPI with health and growth of beef calves and thus, the need to refine protocols for dam vaccination and colostrum intervention in cow-calf operations to meet these higher IgG targets.

An experimental model to induce digital dermatitis in beef calves.

BACKGROUND: Digital dermatitis (DD) is a multifactorial infectious disease affecting the skin on feet of cattle causing erosion and inflammation above the heel bulbs. Some cases of DD cause lameness and significantly impact animal welfare and productivity. While DD has emerged as a concern for the beef industry, key information regarding early detection and its impact on cattle behaviour is lacking. The primary objective of this study was to determine if an established DD experimental model for dairy calves could be used to induce DD lesions in beef calves. A secondary objective was to describe changes in behaviour and pain associated with induction of DD lesions. Eight beef calves acquired from a single cow-calf operator were enrolled in the study. Upon enrolment, calves were evaluated and determined to be free of foot lesions. Within the experimental environment, calves were housed in individual pens and assigned to two groups (mock-inoculated and inoculated). Both hind feet of each calf were enrolled. Within calf, inoculation protocol was consistent, and a 28-day experimental protocol was employed. Two days prior to inoculation, both hind feet of each calf were abraded (area above the heel bulbs and below the dewclaws), moistened, and wrapped to facilitate an anaerobic condition. Feet were inoculated with macerated DD lesion material or mock inoculum and remained wrapped until clinical signs of DD or protocol endpoint. RESULTS: After a period of 14 to 18 days post inoculation, three of five inoculated calves developed clinical signs (lameness), and upon close inspection, DD lesions were present on at least one hind foot. Two of five inoculated calves did not develop lesions within 28 days. Zero of three mock-inoculated calves developed DD. Treponema spp. were detected by quantitative polymerase chain reaction from biopsies of induced lesions. Measurements of behaviour prior to disease induction were numerically different between DD affected and mock-inoculated calves. CONCLUSIONS: An experimental infection model established for dairy cattle was used to successfully induce acute DD lesions in three of five inoculated beef calves. This model can provide a framework to study intervention protocols and to evaluate the impact of DD on behaviour and pain.

Evaluation of 3 refractometers to determine transfer of passive immunity in neonatal beef calves.

BACKGROUND: Refractometry is used to assess transfer of passive immunity (TPI), but studies evaluating different refractometers and appropriate thresholds for recommended target immunoglobulin G (IgG) concentrations for beef calves are limited. OBJECTIVES: To evaluate test performance of digital (DSTP) and optical (OSTP) serum total protein (STP) refractometers and a digital Brix (DBRIX) refractometer for assessment of passive immunity in beef calves. ANIMALS: A total of 398 beef calves from 6 herds, 1 to 7 days of age. METHODS: Serum IgG concentration was estimated by DSTP, OSTP, and DBRIX, and measured by radial immunodiffusion (RID). Correlation coefficients (r) among results were calculated. Optimal STP and Brix thresholds for identification of IgG <10, <16, and <24 g/L were determined using interval likelihood ratios. Refractometer performance and agreement were assessed using areas under the curve (AUC), diagnostic test characteristics, Cohen's kappa (κ), and Bland-Altman analysis. RESULTS: Refractometer results were highly correlated with RID (r = 0.82-0.91) and with each other (r = 0.91-0.95), and overall test performance was excellent (AUC = 0.93-0.99). The STP concentrations of ≤5.1, ≤5.1, and ≤5.7 g/dL and Brix percentages of ≤7.9%, ≤8.3%, and ≤8.7% indicated IgG concentrations <10, <16, and <24 g/L, respectively. Agreement of refractometers with RID was variable (κ = 0.46-0.80) and among refractometers was substantial (κ = 0.62-0.89). CONCLUSIONS AND CLINICAL IMPORTANCE: All refractometers showed good utility as monitoring tools for assessment of TPI in beef calves.

Assessment of Brix refractometry to estimate immunoglobulin G concentration in beef cow colostrum.

BACKGROUND: Brix refractometry can be used to assess colostral immunoglobulin G (IgG) concentration, but studies identifying Brix percentages to detect high- and low-IgG colostrum are lacking for beef cows and interlaboratory agreement is unknown. OBJECTIVES: Evaluate Brix refractometer performance and interlaboratory agreement for assessing beef cow colostrum IgG concentration, including determination of thresholds to identify colostrum containing IgG concentrations <100 g/L and ≥150 g/L. ANIMALS: Beef cows (n = 416) from 11 cow-calf operations in Alberta, Canada. METHODS: Colostral IgG concentrations were measured using radial immunodiffusion (RID) and estimated by Brix refractometry for this retrospective study. Spearman correlation coefficients were assessed between RID and Brix refractometry. Likelihood ratios and misclassification cost-term analysis were used to determine optimal Brix percentages for detecting colostrum containing IgG concentrations <100 g/L and ≥150 g/L. Concordance correlation coefficient (CCC) and Bland-Altman analyses were performed for Brix percentages obtained at 3 different laboratories. RESULTS: Brix percentages obtained at 3 laboratories were positively correlated with IgG results (r = 0.72, 0.68, and 0.76, respectively). Colostrum Brix percentages of <24% and ≥30% were optimal for indicating IgG concentrations of <100 g/L and ≥150 g/L, respectively. Interlaboratory agreement was substantial, with CCC ranging from 0.89 to 0.96 and Bland-Altman analysis showing small mean differences (-1.2% to 0.09% Brix) and narrow limits of agreements (-4.8% to 2.4% Brix) among laboratories. CONCLUSIONS AND CLINICAL IMPORTANCE: Brix refractometry shows good potential for reliably estimating IgG concentrations in beef cow colostrum across multiple laboratories and can be recommended to aid colostrum management decisions on farms.

Pharmacokinetics of oral and subcutaneous meloxicam: Effect on indicators of pain and inflammation after knife castration in weaned beef calves.

Oral meloxicam is labelled for reducing pain and inflammation associated with castration in cattle in Canada, however, subcutaneous meloxicam is only labelled for pain associated with dis-budding and abdominal surgery. The aim of this project was to determine the pharmacokinetic profile of oral (PO; 1.0 mg/kg BW) and subcutaneous meloxicam (SC; 0.5 mg/kg BW), and to assess the effect of meloxicam on physiological and behavioural indicators of pain associated with knife castration in 7-8 month old calves. Twenty-three Angus crossbred beef calves (328 ± 4.4 kg BW) were randomly assigned to two treatments: PO n = 12 or SC n = 11 administration of meloxicam immediately before knife castration. Physiological parameters included salivary and hair cortisol, substance P, haptoglobin, serum amyloid-A, weight, complete blood count, scrotal and rectal temperature. Behavioural parameters included standing and lying behaviour, pen behaviour and feeding behaviour. Data were analyzed using PROC GLIMMIX (SAS), with repeated measures using mixed procedures including treatment as a fixed effect and animal and pen as a random effect. The pharmacokinetic profile of the drug including area under the curve, volume of distribution and clearance was greater (P < 0.05) in PO than SC calves. After surgery, substance P concentrations, white blood cell counts (WBC), weight and lying duration were greater (P < 0.05) in PO than SC calves, while scrotal circumference was lower (P < 0.05) in PO calves than SC calves. Although statistical differences were observed for pharmacokinetic, physiological and behavioural parameters differences were small and may lack biological relevance.

Clinical impacts of administering a nonsteroidal anti-inflammatory drug to beef calves after assisted calving on pain and inflammation, passive immunity, health, and growth.

Assisted calves are often born weak, injured, or oxygen deprived and have a higher risk of morbidity and mortality. The objective was to investigate the impact of using pain mitigation at birth in assisted beef calves on physiological indicators of pain and inflammation, passive immunity, health, and growth. Thirty-three primiparous cows and their calves requiring assistance at birth on two ranches located in southern Alberta were enrolled. Data collected at birth include date and time of calving, calf sex, meconium staining, presentation of calf, and calving difficulty (easy assist: one person manually delivered the calf; difficult assist: delivery by two or more people, or mechanical assistance). Within 10 min of birth, calves were stratified by calving difficulty, randomized to a medication group, and received a subcutaneous dose of meloxicam (0.5 mg/kg BW) or an equivalent volume of placebo. Cow-calf pairs were then placed in individual box stalls for observation and sampling. At birth, 1, 4, and 24 h after birth, heart rate, respiratory rate, and rectal temperature were assessed and blood samples collected to measure indicators of pain and inflammation (cortisol, corticosterone, substance P, and haptoglobin). Serum IgG concentration and failed transfer of passive immunity (serum IgG concentration <24 g/L) were assessed in the 24-h blood samples. Preweaning treatment for disease and mortality information was collected and calves were weighed at 7 to 10 d of age and at weaning. Of the 33 calves enrolled, 17 calves received meloxicam and 16 calves received a placebo. Meloxicam-medicated calves had significantly greater ADG to 7 to 10 d of age (P = 0.05) (mean = 0.9 kg/d; SE = 0.10) compared with placebo-medicated calves (mean = 0.6 kg/d; SE = 0.12). There was no significant effect of meloxicam on physiological indicators of pain and inflammation, standing or nursing by 1 h, passive immunity, health outcomes, or ADG to weaning (P > 0.1). Although this was a small sample population, meloxicam given to assisted calves at birth improved ADG in the first week of life, which may indicate an important production management tool for improving well-being in assisted calves.

Quantifying subclinical trauma associated with calving difficulty, vigour, and passive immunity in newborn beef calves.

This cross-sectional study quantifies subclinical trauma associated with calving difficulty, calf vigour, and passive immunity (PI) in newborn beef calves. The degree of calving difficulty was categorised as: unassisted, easy assist (one or two people manually pulling to deliver the calf) and difficult assist (more than two people pulling, a fetal extractor (ie, calf jack), or caesarean section). Vigour assessment occurred at 10 minutes and blood sampling at 24 hours after birth in 77 beef calves. The measured blood parameters associated with trauma were creatine kinase (CK), aspartate aminotransferase (AST), and haptoglobin. Serum IgG concentration was measured, and an IgG concentration at least 24 g/l was considered as adequate PI. Calving difficulty was associated with elevated levels of CK (P=0.002) and AST (P=0.01), weak suckle reflex (P=0.001), abnormal mucous membrane colour (P<0.0001), and decreased odds of adequate PI (P=0.004). Elevated levels of CK and AST were associated with abnormal mucous membrane colour, incomplete tongue withdrawal and weak suckle reflex at birth (P<0.001). An incomplete tongue withdrawal (P=0.005) and weak suckle reflex (P=0.02) were associated with decreased IgG concentrations. Abnormal mucous membrane colour, incomplete tongue withdrawal, and a weak suckle reflex were associated with decreased odds of having adequate PI (P<0.05). Haptoglobin was not associated with any of the parameters measured. Subclinical trauma was associated with calving difficulty, decreased vigour and decreased odds of having adequate PI. Understanding the impacts of a traumatic birth may aid the development of management strategies for compromised newborn beef calves.

Benchmarking calving management practices on western Canada cow-calf operations.

Benchmarking current calving management practices and herd demographics in the western Canadian cow-calf production system helps to fill the gap in knowledge and understanding of how this production system works. Further investigation into the relationships between management decisions and calf health may guide the development of management practices and protocols to improve calf health, especially in compromised calves after a difficult birth. Therefore, the objectives of this cross-sectional study were to describe current calving management practices on western Canadian cow-calf ranches and to investigate the association of herd demographics with herd-level incidence of calving assistance, morbidity, mortality, and use of calving and colostrum management practices. Cow-calf producers were surveyed in January 2017 regarding herd inventory and management practices during the 2016 calving season. Ninety-seven of 110 producers enrolled in the western Canadian Cow-Calf Surveillance Network responded. Average herd-level incidence of assisted calvings was 4.9% (13.5% heifers, 3.2% cows), stillbirths was 2.1% (3.3% heifers, 1.9% cows), preweaning mortality was 4.5%, and preweaning treatment for disease was 9.4% (3.0% neonatal calf diarrhea, 3.8% bovine respiratory disease, 2.6% other diseases). Greater than 90% of producers assisted calvings and would intervene with colostrum consumption if the calf did not appear to have nursed from its dam. Late calving herds (i.e., started calving in March or later) had significantly lower average herd-level incidence of assistance, treatment for disease, and mortality (P < 0.05). In earlier calving herds (i.e., started calving in January or February) producers had shorter intervals between checking on dams for signs of calving or intervening to assist with a calving (P < 0.05). In early calving herds, producers were more likely to perform hands-on colostrum management techniques such as placing the cow and calf together or feeding stored, frozen colostrum (P < 0.05). There were no associations between herd size and herd-level incidences or management techniques (P > 0.05). This study suggests that in western Canada earlier calving herds are more intensively managed, whereas later calving herds are more extensively managed. Herd demographics may be important to consider when investigating factors associated with management strategies, health, and productivity in cow-calf herds.

Effect of meloxicam and lidocaine administered alone or in combination on indicators of pain and distress during and after knife castration in weaned beef calves.

To assess the effect of meloxicam and lidocaine on indicators of pain associated with castration, forty-eight Angus crossbred beef calves (304 ± 40.5 kg of BW, 7-8 months of age) were used in a 28 day experiment. The experiment consisted of a 2 × 2 factorial design where main factors included provision of analgesia and local anaesthesia. Analgesia consisted of: no-meloxicam (N; n = 24) single s.c. administration of lactated ringer's solution and meloxicam (M; n = 24) single dose of 0.5 mg/kg of s.c. meloxicam. Local anesthesia consisted of: no-lidocaine (R; n = 24) ring block administration of lactated ringer's solution or lidociane (L; n = 24) ring block administration of lidocaine. To yield the following treatments: no meloxicam + no lidocaine (N-R; n = 12), no meloxicam + lidocaine (N-L; n = 12), meloxicam + no lidocaine (M-R; n = 12) and meloxicam + lidocaine (M-L; n = 12). Salivary cortisol concentrations were lower (lidocaine × time effect; P < 0.01) in L calves than R calves 0.5 and 1 hours after castration, while concentrations were lower (meloxicam × time effect; P = 0.02) in M calves than N calves at 2, 4 and 48 hours. The serum amyloid-A concentrations were greater (lidocaine × time effect; P < 0.01) in R calves than L calves on days 1, 3, 21 and 28 after castration. Haptoglobin concentrations were greater (meloxicam × time effect; P = 0.01) in N calves than M calves 24 and 48 hours after castration. Lower (lidocaine effect; P < 0.01) visual analog scale (VAS) scores, leg movement frequencies and head movement distance were observed in L calves than R calves at the time of castration. Escape behaviour during castration was lower (lidocaine effect; P < 0.05) in L calves than R calves based on data captured with accelerometer and head gate devices. Scrotal circumference had a triple interaction (lidocaine × meloxicam × time; P = 0.03), where M-R calves had greater scrotal circumference than M-L calves 28 d after castration, but no differences were observed between both groups and N-R and N-L calves. No differences (P > 0.05) were observed for average daily gain (ADG), weights or feeding behaviour. Overall, both lidocaine and meloxicam reduced physiological and behavioural indicators of pain. Although there was only one meloxicam × lidocaine interaction, lidocaine and meloxicam reduced physiological and behavioural parameters at different time points, which could be more effective at mitigating pain than either drug on its own.

Use of topical healing agents on scrotal wounds after surgical castration in weaned beef calves.

Angus bulls (n = 48) were randomly assigned to control (castrated without the application of a postoperative healing agent) or surgical castration followed by either the application of a topical germicide, aluminum powder spray, or liquid bandage. The objective of this study was to determine the efficacy of commercial topical healing agents in improving wound healing and reducing inflammation and secondary infection after surgical castration. Indicators of wound healing included scrotal area temperature (determined by infrared thermography), scrotal circumference, clinical state of the scrotum score, and the wound healing score. Pain sensitivity was measured using a Von Frey anesthesiometer. The healing agents used in this study did not improve indicators of healing such as swelling and healing rate scores or indicators of inflammation including scrotal temperature and circumference of surgical castration lesions. Pain sensation associated with surgical castration was found to last 35 d after the procedure.

Usage d'agents cicatrisants topiques sur des blessures scrotales après la castration chirurgicale chez des veaux de boucherie sevrés. Quarante-huit taureaux Angus ont été assignés au hasard à la castration témoin (castration sans l'application d'un agent cicatrisant postopératoire) ou à la castration chirurgicale suivie soit de l'application d'un germicide topique, d'un poudre à l'aluminium en vaporisateur ou d'un pansement liquide dans le but de déterminer l'efficacité des agents cicatrisants topiques commerciaux pour l'amélioration de la guérison des plaies et la réduction de l'inflammation et de l'infection secondaire après la castration chirurgicale. Les indicateurs de cicatrisation des plaies incluaient la température de la région scrotale déterminée par thermographie infrarouge, la circonférence scrotale, le pointage de l'état clinique du scrotum et le pointage de la cicatrisation de la plaie; et la sensibilité à la douleur mesurée à l'aide d'un anesthésiomètre Von Frey. Les agents cicatrisants utilisés dans cette étude n'ont pas amélioré les indicateurs de cicatrisation comme l'enflure et les notes de la rapidité de cicatrisation ou des indicateurs de l'inflammation qui incluaient la température scrotale et la circonférence des lésions de castration chirurgicale. Il a été constaté que la sensation de douleur associée à la castration chirurgicale durait 35 jours après l'intervention.(Traduit par Isabelle Vallières).

Effects of changing freestall area on lameness, lying time, and leg injuries on dairy farms in Alberta, Canada.

Cow comfort is of increasing importance in the dairy industry, due to an increased focus on animal welfare. However, whether producer changes to the cows' environment affect cow comfort has not been well characterized. Our objectives were to: (1) quantify the effect of freestall area changes on the prevalence of lameness, leg injuries, and average lying time; and (2) compare cow comfort outcomes on farms that had never had an assessment of cow comfort to farms that had had a previous assessment of cow comfort. A sample of 60 Holstein-Friesian cows were selected on each of 15 farms that made changes to the freestall area after an assessment of cow comfort (change, CHG); 15 farms that did not make changes to the freestall area after an assessment of cow comfort (no change, NC); and 14 farms that had yet to be evaluated (new farms, NF). Cows in NC and NF were lame 1.50 and 1.71 times more often, respectively, than cows on CHG farms. Additionally, daily lying time was 0.33 and 0.62 h/d lower in NC and NF, respectively, than on CHG farms. The prevalence of hock and knee injuries was not different among the 3 groups of farms. No differences were detected in the parameters of interest when comparing NF with NC farms; therefore, we concluded that the NC group was not biased by a previous assessment of cow comfort. Farms in the CHG group had a lower prevalence of lame cows and greater lying time than the NC and NF groups.

Energy reallocation to breeding performance through improved nest building in laboratory mice.

Mice are housed at temperatures (20-26 °C) that increase their basal metabolic rates and impose high energy demands to maintain core temperatures. Therefore, energy must be reallocated from other biological processes to increase heat production to offset heat loss. Supplying laboratory mice with nesting material may provide sufficient insulation to reduce heat loss and improve both feed conversion and breeding performance. Naïve C57BL/6, BALB/c, and CD-1 breeding pairs were provided with bedding alone, or bedding supplemented with either 8 g of Enviro-Dri, 8 g of Nestlets, for 6 months. Mice provided with either nesting material built more dome-like nests than controls. Nesting material improved feed efficiency per pup weaned as well as pup weaning weight. The breeding index (pups weaned/dam/week) was higher when either nesting material was provided. Thus, the sparing of energy for thermoregulation of mice given additional nesting material may have been responsible for the improved breeding and growth of offspring.

Winning the genetic lottery: biasing birth sex ratio results in more grandchildren.

Population dynamics predicts that on average parents should invest equally in male and female offspring; similarly, the physiology of mammalian sex determination is supposedly stochastic, producing equal numbers of sons and daughters. However, a high quality parent can maximize fitness by biasing their birth sex ratio (SR) to the sex with the greatest potential to disproportionately outperform peers. All SR manipulation theories share a fundamental prediction: grandparents who bias birth SR should produce more grandoffspring via the favored sex. The celebrated examples of biased birth SRs in nature consistent with SR manipulation theories provide compelling circumstantial evidence. However, this prediction has never been directly tested in mammals, primarily because the complete three-generation pedigrees needed to test whether individual favored offspring produce more grandoffspring for the biasing grandparent are essentially impossible to obtain in nature. Three-generation pedigrees were constructed using 90 years of captive breeding records from 198 mammalian species. Male and female grandparents consistently biased their birth SR toward the sex that maximized second-generation success. The most strongly male-biased granddams and grandsires produced respectively 29% and 25% more grandoffspring than non-skewing conspecifics. The sons of the most male-biasing granddams were 2.7 times as fecund as those of granddams with a 50∶50 bias (similar results are seen in grandsires). Daughters of the strongest female-biasing granddams were 1.2 times as fecund as those of non-biasing females (this effect is not seen in grandsires). To our knowledge, these results are the first formal test of the hypothesis that birth SR manipulation is adaptive in mammals in terms of grandchildren produced, showing that SR manipulation can explain biased birth SR in general across mammalian species. These findings also have practical implications: parental control of birth SR has the potential to accelerate genetic loss and risk of extinction within captive populations of endangered species.

Impact of nesting material on mouse body temperature and physiology.

In laboratories, mice are housed at 20-24 °C, which is below their lower critical temperature (≈30 °C). Thus, mice are potentially cold stressed, which can alter metabolism, immune function, and reproduction. These physiological changes reflect impaired wellbeing, and affect scientific outcomes. We hypothesized that nesting material would allow mice to alleviate cold stress by controlling their thermal microenvironment, thus insulating them, reducing heat loss and thermogenic processes. Naïve C57BL/6, CD-1, and BALB/c mice (24 male and 24 female/strain in groups of 3) were housed in standard cages at 20 °C either with or without 8 g nesting material for 4 weeks. Core body temperature was followed using intraperitoneal radio telemetry. The thermal properties of the nests were assessed using a thermal imaging camera, and related to nest quality. Higher scoring nests were negatively correlated with the mean radiated temperature and were thus more insulating. No effects of nesting material on body temperature were found. CD-1 mice with nesting material had higher end body weights than controls. No effect was seen in the other two strains. Mice with the telemetry implant had larger spleens than controls, possibly indicating an immune response to the implant or low level infection from the surgery. BALB/c mice express less mRNA for the UCP1 protein than mice without nesting material. This indicates that BALB/c's with nesting material do not utilize their brown fat to create heat as readily as controls. Nests can alleviate thermal discomfort by decreasing the amount of radiated heat and reduce the need for non-shivering thermogenesis. However, different strains appear to use different behavioral (through different primary modes of behavioral thermoregulation) and physiological strategies (utilizing thermogenesis to different degrees) to maintain a constant body temperature under cool standard laboratory ambient temperatures.

Heat or insulation: behavioral titration of mouse preference for warmth or access to a nest.

In laboratories, mice are housed at 20-24°C, which is below their lower critical temperature (≈30°C). This increased thermal stress has the potential to alter scientific outcomes. Nesting material should allow for improved behavioral thermoregulation and thus alleviate this thermal stress. Nesting behavior should change with temperature and material, and the choice between nesting or thermotaxis (movement in response to temperature) should also depend on the balance of these factors, such that mice titrate nesting material against temperature. Naïve CD-1, BALB/c, and C57BL/6 mice (36 male and 36 female/strain in groups of 3) were housed in a set of 2 connected cages, each maintained at a different temperature using a water bath. One cage in each set was 20°C (Nesting cage; NC) while the other was one of 6 temperatures (Temperature cage; TC: 20, 23, 26, 29, 32, or 35°C). The NC contained one of 6 nesting provisions (0, 2, 4, 6, 8, or 10g), changed daily. Food intake and nest scores were measured in both cages. As the difference in temperature between paired cages increased, feed consumption in NC increased. Nesting provision altered differences in nest scores between the 2 paired temperatures. Nest scores in NC increased with increasing provision. In addition, temperature pairings altered the difference in nest scores with the smallest difference between locations at 26°C and 29°C. Mice transferred material from NC to TC but the likelihood of transfer decreased with increasing provision. Overall, mice of different strains and sexes prefer temperatures between 26-29°C and the shift from thermotaxis to nest building is seen between 6 and 10 g of material. Our results suggest that under normal laboratory temperatures, mice should be provided with no less than 6 grams of nesting material, but up to 10 grams may be needed to alleviate thermal distress under typical temperatures.

Increasing the frequency of co-mingling piglets during the lactation period alters the development of social behavior before and after weaning.

The purpose of this study was to determine how increasing the frequency of co-mingling affected piglets' behavior development before and after weaning. Co-mingling once (CM1), piglets interacted with 1 unfamiliar litter Days 10-18 after birth; co-mingling twice (CM2), piglets interacted with 1 unfamiliar litter Days 10-14; and with another, Days 14-18. Control (CM0) piglets did not interact with unfamiliar litters before Day 18 (n = 16 litters per treatment). The study weighed piglets and recorded ear-injury scores throughout the experiment; however, there were no treatment differences. The CM2 piglets spent less time engaged in aggressive interactions (p < .05) than did CM0 piglets following mixing at weaning. During the social challenge, CM2 piglets spent more time in proximity to one another, had shorter latencies to first aggressive interaction, and spent less time fighting than did CM0 piglets (p < .05). During the social recognition test, CM2 piglets recognized the stimulus piglet at a faster rate than did CM0 piglets (p < .05). Overall, CM2 resulted in changes to some social behaviors compared with CM0 but not with CM1.

Measuring motivation in swine: the food-metric scale.

Understanding how nonhuman animals such as swine respond to their environment and understanding how to provide them with a good quality of life involves using a range of experimental approaches. More and more, ethological researchers are turning to operant methods to answer some of these questions. Employing an operant such as a lever, researchers can assess how hard animals will work to get access to environmental resources: increased space or social contact. It is difficult, however, to determine how the effort made by the animals relates to the degree to which they need the resource and, in particular, how to interpret intermediate levels of responding. One approach to understanding the level of need is to compare it with familiar states of deprivation such as hunger. Food is an environmental resource known to range from low to high value depending on deprivation level. Depriving animals of a fixed proportion of their daily ad libitum intake allows the animals to demonstrate the levels of responding produced at satiation: 23 hr deprivation and a range of intermediate points. The resulting scale has both empirical and intuitive value and can help in understanding the value of various degrees of operant effort. Ultimately, this information will help in deciding which environmental conditions should be provided to swine as part of routine husbandry.

Little and often? Maintaining continued performance in an automated T-maze for mice.

Operant and maze tasks in mice are limited by the small number of trials possible in a session before mice lose motivation. We hypothesized that by manipulating reward size and session length, motivation, and hence performance, would be maintained in an automated T-maze. We predicted that larger rewards and shorter sessions would improve acquisition; and smaller rewards and shorter sessions would maintain higher and less variable performance. Eighteen C57BL/6J mice (9 per sex) acquired (criterion 8/10 correct) and performed a spatial discrimination, with one of 3 reward sizes (.02, .04, or .08 g) and one of 3 session schedules (15, 30, or 45 min sessions). Each mouse had a total of 360 min of access to the maze per night, for two nights, and averaged 190 trials. Analysis used split-plot GLM with contrasts testing for linear effects. Acquisition of the discrimination was unaffected by reward size or session length/interval. After-criterion average performance improved as reward size decreased. After-criterion variability in performance was also affected. Variability increased as reward size increased. Session length/interval did not affect any outcome. We conclude that an automated maze, with suitable reward sizes, can sustain performance with low variability, at 5-10 times faster than traditional methods.