Calf Feeding Research Articles

PSVI-1 Supplemented milk replacer improves feed transition of dairy bull-calves

Abstract Neonatal calves are affected by pathogenic infections, compounded by stress, leading to enteric and respiratory disorders accounting for about 7.8% mortality rate and annual treatment costs exceeding $250 million. Federal restrictions on antibiotic use due antimicrobial resistance in humans has opened the door for viable alternatives like rumen enhancements which have been reported to aid the establishment of beneficial rumen flora leading to improved health and performance. It is hypothesized that nutritional formulation of milk replacers to help the calf prevent or cope with diarrhea can provide a leeway that will ensure better animal performance and transition to solid feed. The objective of study was to evaluate the performance of dairy bull-calves fed nutritionally supplemented milk replacers. Three milk replacers were tested with or without supplementation of metabolic enhancements (Control: no metabolic enhancer; Added: milk replacer with metabolic enhancer added at the time of mixing milk in shuttle; Composite: produced along with metabolic enhancer. Dairy bull-calves (n = 60; 2 to 5 d-old) were grouped into three treatments of milk replacers. The study lasted for 10 wk; 6 wk of milk-feeding and 4 wk of calf starter feeding. Body weights (BW) were taken on a weekly basis, while calf starter intake was measured daily and data were analyzed using one-way analysis of variance. Calves fed milk replacer with composite metabolic enhancer recorded the greatest intake and final BW over the 10-wk period. Calves fed milk replacer with added metabolic enhancer at the point of milk mixing recorded the poorest data in terms of BW gain and final BW. Calves fed metabolic enhancer, either added or composite recorded a better weaning and transition to solid feed from milk feeding. Calves fed control milk replacer experienced a poor transition from milk feeding to solid feed. It is concluded that composited rumen metabolite enhancers in milk replacer supported greater starter intake, average daily gain and better transition of calves to solid feed, and is recommended for the feeding of neonatal calves.

PSX-21 Supplementing essential oil blend and fumaric acid in calf feed influenced rumen fermentation and greenhouse gases emission

Abstract Essential oils (EO) and fumaric acid (FA) are known for their ability to reduce greenhouse gas (GHG) emissions in ruminant animals. This study aimed to investigate the combined impact of essential oil blend (EOB) and FA (EF) on in vitro fermentation, total gas and volatile fatty acid (VFA) production and GHG emissions of a calf feed in a 24 h batch culture study. Rumen-cannulated black Angus beef cows (n = 3) served as inoculum donors. The calf feed contained 910, 5.8, 70.9, 792, 111, 72 g/kg dry matter (DM), fat, ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL), respectively. The EOB contained equal proportions of ginger, anise, peppermint, oregano and thyme. FA was added at 3% along with EOB at 10, 20, 30 and 40 µL/g calf feed. Five treatments evaluated were Control (without additives), EF10, EF20, EF30, and EF40. Results showed that pH and digestibility of DM, NDF, ADF were not significantly (P > 0.05) affected by the EF treatments (Table 1). ADL digestibility decreased linearly (P < 0.001) with increasing EF dosage. EF40 increased (P < 0.05) cellulose digestibility by approximately 11% compared with EF10. Total gas, methane and carbon dioxide production decreased (linear, quadratic, P < 0.001) with EF inclusion (Table 2). Ammonia concentration decreased linearly (P = 0.009) with increasing EF dosage, while hydrogen sulfide gas was not affected. EF inclusion reduced (P < 0.001) total VFA, acetate but increased propionate and butyrate proportion (Table 3). In conclusion, the combination of EOB and FA effectively mitigated GHG emissions without compromising nutrient digestibility in calves. Therefore, incorporating EOB at 10 µL/g and FA at 3% in calf feed is recommended as an effective nutritional strategy to reduce GHG emissions in calves.

271 Does social buffering amongst familiar weaned beef calves mitigate castration stressors?

Abstract Co-mingling of beef feeder calves from multiple sources results in biological and behavioral stressors. This study is part of a project exploring social relationships between individual beef cattle and potential benefits of social buffering during stress events. Here, the specific objective was to explore whether feeder calves form preferential relationships which buffer them from surgical castration pain. Within the experiment, two treatment groups were established: Familiar calves were defined as calves who shared a source farm with two other calves in the pen, and Unfamiliar calves were defined as calves who did not share a source with any other pen-mates. It was hypothesized that Familiar calves would exhibit more lying, fewer pain-related behaviors, and fewer agonistic interactions following surgical castration than Unfamiliar pen-mates. Weaned beef bull calves [n = 102, body weight (BW) range ± SD = 112.95 to 370.10 ± 67.8 kg] from 23 source farms were randomly assigned to home pens, each comprised of three Familiar calves and three Unfamiliar calves. Cameras placed above the pens recorded video from which postural (standing and lying), social (agonistic and bunk displacements) and pain-related behaviors (wound checking and hind leg stamping) were quantified. Cattle were handled through a hydraulic squeeze chute once weekly over four consecutive weeks for data collection and standard processing procedures. On d 14 relative to arrival, calves were surgically castrated with multimodal pain mitigation. During all processing events, calves were marked with livestock paint for behavioral observations. Behavior was observed continuously for 15 min at five different time points (0 h, 1 h, 4 h, 24 h, 48 h) relative to when the last calf returned to the home pen after processing, and researchers were blind to treatment allocation. These time periods corresponded to expected periods when pain was absent and present based on duration of local anesthesia and systemic pain relief. Calf was the experimental unit. For the purpose of this abstract, data from the 48 h periods following d 7 and 14 were analyzed using the PROC GLIMMIX procedure of SAS; the model included treatment (Familiar, Unfamiliar) by week interaction. A P-value of ≤ 0.05 was considered significantly different. Regardless of treatment, preliminary analyses identified decreased lying (P < 0.02) and increased wound checking (P < 0.01) 48h following castration (d 14) when compared with the previous week (d 7). There were no observed differences for hindleg stamping (P = 0.2), agonistic behaviors (P > 0.06) or bunk displacement (P = 0.09). Based on preliminary analyses, we did not observe evidence of social buffering effects on castration stress during the immediate post-surgical period.

The Effect of Different Forms of Solid Feed on Biochemical Parameters in Blood Plasma of Calves

Abstract The study examined how different solid feeds affected the biochemical parameters in calf plasma. The experiment involved a control group and three test groups of calves, each fed with a different starter mixture. The results showed significant differences in some biochemical parameters between the feeding groups. Calves in groups P1 and P3 had a statistically higher glucose concentration in blood plasma compared to group C. Calves from group P3 had a higher concentration of urea in blood plasma than calves from group C. Calves in groups P1 and P3 also had higher concentrations of total protein and globulin in blood plasma compared to group C. The concentration of inorganic phosphate in the blood plasma of calves from group P3 was significantly higher than that of group C. Female calves in the experimental groups showed a lower concentration of NEFA at three months of age compared to the control group. It was concluded that feeding calves with a starter mixture containing whey and easily digestible protein had a positive effect on the nutritional status and energy balance of the calves.

264 Dakota Feeder Calf Show: Twenty-two years of producer retained ownership at NDSU

264 Dakota Feeder Calf Show: Twenty-two years of producer retained ownership at NDSU

Effects of a Proprietary Kelp Blend Product on Enteric Methane Production and Tissue Residues in Cattle.

Three experiments were performed investigating bovine enteric methane (CH4) production inhibition using a proprietary kelp blend product (PKBP) containing a halogenated methane analog (i.e., bromoform). Calves were fed a corn-silage basal diet top-dressed with the assigned treatment, with rations provided at 1.5 × NEm in Experiments 1 and 2 (n = 12 and 6 steers, respectively) and ad libitum in Experiment 3 (n = 9 steers). In Experiment 1, we evaluated bromoform's potency in decreasing CH4. Dry matter intake (DMI) was not affected by treatment (p ≥ 0.11; 0 vs. 52.5 ± 10.5 ppm bromoform), whereas bromoform supplementation decreased CH4 (p < 0.01). In Experiments 2 and 3, treatments were 0, 9.5 ± 1.5, or 20 ± 3 ppm bromoform. In Experiment 2, we examined CH4 recovery following bromoform removal from the ration. Bromoform treatments were fed on d1, but not the subsequent 8 d, to investigate residual effects. On d1, CH4 was below limits of detection for 20 ppm bromoform inclusion. Across days, a cubic response (p < 0.01) was observed with 20 ppm bromoform inclusion, but not with 0 and 9.5 ppm inclusion levels. Experiment 3 (30 d finishing trial) tested bromoform effects on feeder calves. DMI (p = 0.53), average daily gain (p = 0.55), and gain:feed (p = 0.82) were not influenced by bromoform inclusion. Bromoform residues were undetectable in liver, kidney, adipose, and muscle samples collected at harvest. These experiments demonstrated that cattle fed PKBP experience short-term reductions in CH4 without tissue accumulation of bromoform and without evidence of effects on animal growth or feed consumption.

Farm management practices and host species richness associated with higher likelihood of tuberculosis positive farms in Western Spain

Despite enormous efforts, complete animal tuberculosis (TB) eradication has only been achieved in few regions. Epidemiological analyses are key to identify TB risk factors and set up targeted biosecurity measures. Here, we conducted an in-depth characterization of 84 extensive beef cattle farms from a high TB prevalence region in Western Spain, and assessed how farm management and wildlife presence on farms contribute to cattle TB risk. Twenty-six out of 84 variables were associated with cattle farm TB positivity. Farm management variables associated with TB positivity included older cattle, larger herd size, highly fragmented farm structure and greater connectivity between farms. TB-positive farms provided supplemental feed over a higher number of months, used calf feeders, and had higher number of waterholes. Detecting Eurasian wild boar (Sus scrofa), red fox (Vulpes vulpes), European badger (Meles meles), roe deer (Capreolus capreolus), or Egyptian mongoose (Herpestes ichneumon) on cattle farms was also associated with farm TB positivity. The best ordinal regression model indicated that in farms with a large herd size (> 167 animals) the odds of being positive or recurrently positive (versus negative) was 7.34 (95% CI = 2.43–23.51) times higher that of farms with small herd size. Further, for every additional host species detected in the farm premises, the odds of being TB-positive increased 56%. We conclude that both cattle management and wildlife need to be targeted for successful TB control in grazing-based farming systems.

Assessing solvent impact on Moringa oleifera seed cake nutrition: towards sustainable food and feed production

Abstract Moringa oleifera seed cake, a byproduct of oil extraction, represents a valuable resource for animal and human nutrition. However, solvent selection during extraction significantly influences the cake’s composition. This study aims to evaluates Moringa seed cakes extracted with ethanol, methanol, and hexane, employing proximate analysis, metal content assessment, and microbial testing. The drying process involved hexane seed cake at 55°C, and ethanol and methanol cakes at 70°C for one hour. Proximate analysis indicates that all seed cakes surpass quality standards (SNI, 3571-2009) for ash and crude protein. Hexane seed cake, distinguished by the highest ash (6.4972%) and crude protein (42.1169%), is identified as suitable for bakery and snacks, featuring optimal calcium (0.9697%) and minimal crude fiber (1.9386%), aligning with chicken feed standards (SNI, 8173.2:2015). Methanol seed cake, rich in crude fat (15.7618%) and calories (6549.89 Kcal/Kg), proves suitable for fishery feed. Ethanol seed cake, abundant in crude fiber (30.0319%), is advantageous for calf feed and serves as a foundational ingredient in bakery and snacks. Metal content and microbial contamination adhere to Indonesian standards (SNI, 3751-2009) and (SNI, 3148.2:2009), solidifying Moringa seed cake as a viable alternative across diverse applications.

The evolution of sensor-based technologies in dairy production

Sensor-based management is growing rapidly in dairy farming. Activity, behavior and rumination monitors and data from au­tomated milking systems and calf feeders are established man­agement tools and hold promise for earlier or more efficient de­tection of health problems. However, gaps remain in validation and especially in turning streams of data into actionable infor­mation. On average, dairy herds can achieve comparable re­productive performance with management emphasizing estrus detection by activity monitors or timed insemination programs, but herd-specific variables will affect relative performance. Sensor-based screening of fresh cows may be useful to save la­bor or reduce disruptions to cows’ routines, but more validation is needed before this can augment or offset skilled, rational de­tection of health problems.

Effect of Milk-Feeding Frequency and Calcium Gluconate Supplementation on Growth, Health, and Reproductive and Metabolic Features of Holstein Heifers at a Rearing Farm.

We compared the effects of milk-feeding in 288 Holstein calves (72 per group) which were fed twice (2F) or thrice (3F) daily, with or without the addition of hydrogenated fat-embedded calcium gluconate (G) supplemented in the starter food and in the daily diet up to the age of 9 months, on the calves' metabolism, growth, health, and reproductive efficiency up to first pregnancy. The calves received 6 L of milk replacer (130 g/L) and had ad libitum access to water and textured calf starter with or without gluconate. Gluconate supplementation promoted a "catch-up" in growth in supplemented calves compared to their counterparts that did not receive gluconate. Gluconate appeared to reduce animal metabolic stress during key events, such as weaning and transfer into open-door pens, reducing fructosamine (352.61 vs. 303.06 in 3FG and 3F, respectively; p = 0.028) and urea (3F revealed the highest values compared with the other three groups: 19.06 for 3F vs. 13.9 (2F), 13.7 (2FG), and 14.3 (3FG), respectively, p = 0.002) from weaning onwards. The feeding of dairy calves with milk replacer three rather than two times per day tended to be associated with better health from weaning to 4 months old; parameters such as ultrasound lung score and calf health score improved over time (p < 0.001). Thrice-daily feeding with milk replacer tended to reduce the number of artificial inseminations per pregnancy in heifers by 0.2 points (p = 0.092). We confirmed significant correlations between early health and growth parameters and reproductive efficiency and a positive correlation between body weight and average daily weight gain and the thickness of the back fat layer in young heifers (r = 0.245; p < 0.0001; r = 0.214; p < 0.0001 respectively). Our study was conducted on a commercial farm with reasonably effective animal management, so baseline welfare was likely satisfactory.

Can individual variation in food neophobia explain variability in dairy calf feeding behavior patterns and performance?

Food neophobia is the avoidance of novel feeds, arising from an attempt to avoid potentially toxic and unwanted feeds, and is very common in ruminants. In commercial dairy settings, hesitancy to consume novel feeds is detrimental to animal performance and may be associated with other traits that can negatively affect animals in intensive and modern production systems. The aim of this study was to investigate the relationship between food neophobia and the development of solid and milk feeding behaviors, and consequently with calf performance up to two weeks post-weaning. We subjected dairy calves at 83 ± 3 d of age to a food neophobia test with a novel feed (corn silage-based total mixed ration), a familiar feed (alfalfa hay), and an empty container. Behaviors measured from this food neophobia test were condensed into three factors using a principal component analysis: ‘Feed Avoidant’, ‘Active’, and ‘Attentive’. A regression analysis was performed to assess if scores for the three factors were associated with feeding behavior patterns measured via an automatic feeder system, including total milk intake, rewarded and unrewarded visits to the milk feeder, total calf starter intake, and age at which calves first consumed ≥ 1 kg of calf starter. Factor 1 (‘Feed Avoidant’) was positively associated with the number of rewarded visits to the automated milk feeder but was not associated with intake of calf starter or milk replacer, nor performance of dairy calves. The other factors identified from the food neophobia test showed associations with feeding behavior patterns and performance. Factor 2 (‘Active’) was positively associated with calf starter intake during the weaning, post-weaning, and total periods, and was associated with a younger age at which calves consumed 1 kg of calf starter. Factor 3 (‘Attentive’) was positively associated with number of rewarded visits to the feeder during preweaning, increased calf starter intake during weaning and total periods, and higher preweaning ADG. These results suggest that individual variation in the willingness to interact with novel and familiar feeds may not play a large role in the development of solid feeding behaviors or performance of group housed dairy calves, but other traits identified from the food neophobia test are associated with performance and feeding behavior that can be measured in standardized tests.

Milk replacer feeding once or twice a day did not change the ruminal metabolomic profile and the microbial diversity of dairy calves from birth to weaning

In commercial dairy production systems, feeding calves once a day could be an alternative to reduce labor expenses. Several studies comparing once (OAD) versus twice (TAD) a day milk feeding systems have not evidenced differences in calf growth, rumen development, blood parameters or health scores, but impact on ruminal microbiota remains to be investigated. The objective of this study was to determine the effects of OAD or TAD on the establishment of the ruminal microbiota and its metabolic activity. Sixteen male calves (45.9 ± 5.7 kg at birth) were involved in the trial from birth to weaning (63 d). After the colostrum phase, 2 feeding programs based on a milk replacer were tested and calves were allocated to these programs on d 5. To study the establishment of the bacterial community, ruminal fluid was obtained from each calf one hour after the morning meal at 7 (d 7), 35 (d 35) and 63 (d 63) days of age. The ruminal metabolome was evaluated at a 7 d interval from d 1 to d 63. Ruminal microbiota and metabolite profiles were characterized by 16 S rRNA gene sequencing- and by H-NMR spectroscopy, respectively. Our results showed that feeding milk replacer once or twice a day did not change the ruminal microbiota and metabolites of dairy calves from birth to weaning. Microbial data showed that diversity and richness increased with age, suggesting a shift from an heterogeneous and less diverse community after birth (d 7) to a more diverse but homogeneous community at 35 and 63 d. These findings suggest that feeding milk once a day can be successfully applied to a calf feeding system without compromising microbial establishment and functions.

Enrichment of medium-quality colostrum by adding colostrum replacer, combined or not with transition milk in the feeding of dairy calves

Fifty Holstein calves were allocated in randomized blocks and distributed in a 2 × 2 factorial arrangement; (A) two sources of Ig: (1) Control: bovine colostrum (25% Brix); (2) Enriched colostrum: mid-quality bovine colostrum (20% Brix) enriched with colostrum replacer to 25% Brix; and (B) two transition feeding diets: (1) Whole milk (WM): supply of 4 L/day of whole milk for 3 days after the colostrum feeding; and (2) Formulated transition milk (FTM): supply 4 L/day of whole milk enriched with 70 g/L of colostrum replacer for 3 days after the colostrum feeding. Blood samples were collected at 0, 24, 48, and 72 h of age to determine total serum protein (TSP), glucose, non-esterified fatty acids (NEFA), erythrocyte and leukocyte concentrations. IgG was measured at 48 h. During the preweaning period, calves received 6 L/day of whole milk. Blood samples were collected weekly to determine TSP, glucose, and lactate. The colostrum protocols were equally efficient for transfer of passive immunity with IgG concentration at 48 h ≥ 49.6 g/L. Colostrum or transition feeding program did not influence the erythrocyte and leukocyte concentrations. The TSP concentration measured until 72 h was higher for calves fed maternal colostrum. Calves fed milk in the transition period had higher glucose concentrations. Calves receiving bovine colostrum and FTM had higher glucose concentrations in the preweaning period, while the enriched colostrum decreased plasma lactate concentrations. In summary, enrichment of mid-quality colostrum is an alternative in situations of a shortage of high-quality colostrum; however, feeding 4 L/day of FTM only for 3 days after colostrum feeding does not show additional benefits.

Multidrug-Resistant Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli in a Dairy Herd: Distribution and Antimicrobial Resistance Profiles.

This study investigated the presence, distribution, and antimicrobial resistance profiles of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in a dairy herd located in Northern Italy. The feces of clinically healthy calves, their mothers, and the cows treated for mastitis, as well as water, environmental samples, and waste milk were collected and subjected to bacteriological culture on CHROMagarTM ESBL plates. A questionnaire was administered to identify risk factors. The isolates were identified as E. coli by MALDI-TOF MS and subjected to the double-disk synergy test (DDST) and minimal inhibitory concentration (MIC) assay. As a result, ESBL E. coli was isolated from the feces of 28 of 37 (75.67%) calves, the feces of 2 of 3 (66.67%) treated cows, 8 of 14 (57.15%) environmental samples, and waste milk. All ESBL isolates showed multiple resistances and were categorized as multidrug-resistant (MDR). Several risk factors for ESBL E. coli selection and diffusion were identified, including lack of routine cleaning of calf feeding and housing equipment, administration of waste milk to male calves, and blanket dry cow therapy. In conclusion, this study highlighted the presence of MDR, ESBL E. coli in the feces of most dairy calves, and their association with different sample sources. Accordingly, adding to the prudent use of antibiotics, the adoption of adequate farm hygiene and biosecurity measures might also help prevent the spread and transmission of ESBL E. coli within the herd.

Milk consumption and behavior of calves in automated calf feeders as early indicators of weaning liveweight

Modern intensive dairy farming relies on data to aid and prioritize management decisions made on farm. Decisions made early in an animal's life can have lasting effects on welfare, productivity, longevity, and profitability. Precision technology such as automated calf feeders (ACF) allow the customization of feeding programs, but despite this, weaning weights (WWT) vary substantially between calves. This observational study used a 3-yr dataset comprising 1,440 female Holstein Friesian calves at a single intensive commercial dairy farm (Dairy Australia feeding system 5; indoor, total mixed ration) using ACF to (1) determine the variability in WWT (as a proxy of animal performance) of calves within this system; (2) identify the contributing factors responsible for the variation in WWT; and (3) identify potential early management intervention points that could be indicative of the performance of calves at weaning within the system. Calves entered the ACF at 10 d of age with 12 calves per ACF; calves were weighed at birth and weaning using weigh scales. We discovered a large range of calf WWT (41–118 kg/head) at ~60 d of age despite the application of strict uniform management protocols. Our results from modeling showed that WWT was significantly and positively associated with birth weight (BWT), with low BWT calves (<36 kg) achieving an average of 70 kg weight at weaning. In contrast, heavier BWT (>36 kg) calves achieved an average of 82 kg at weaning. Based on calf feeder data, cumulative milk consumption and cumulative unrewarded visits to the feeder, as well as BWT, were identified as indicators of greater WWT as all these were highly significant terms in the model for WWT. Results suggest that quantifying consumption and number of visitations to the ACF at d 5 may allow farmers to identify, with time to intervene, calves underperforming within the feeder or system, therefore increasing their potential for growth. Additionally, this demonstrated that greater milk consumption (>30 kg) and interaction with the feeder up to d 5 in the feeder is more likely to yield a WWT >75 kg, identifying a potential point for management intervention for calves below consumption and interaction thresholds (e.g., by developing alarm systems based on consumption or visitation number).

38 Assessment of retained ownership extension programming in southeastern beef cattle herds

Abstract Retained ownership is a marketing strategy that involves maintaining ownership of cattle through the feedyard stage. This strategy deviates from the traditional marketing time for many Southeast U.S. cow-calf producers, which is usually centered around weaning. Selected benefits of retained ownership for the producer includes capturing information on improved genetics and being able to take full advantage of health and management programs. Producers are often unaware of how calves perform further down the production line, leaving valuable information on the table as far as management styles and genetic selection goes. Extension programs such as Alabama’s Pasture to Rail and Arkansas’ Grass to Grid were developed to help producers retain ownership on beef calves and learn how their cattle perform in the feedyard phase. These programs provide opportunities for producers to receive feedback about the profitability of the cattle they are producing, learn more about the cattle industry beyond their sector, and investigate the use of other marketing strategies. Once cattle are marketed, producers receive data on their cattle such as average daily gain, estimated feed conversion, detailed carcass data, and health performance metrics. Extension educators can help producers analyze and understand how management and genetic selection affected these outcomes and changes that could be made to their operation. These programs have also been utilized in integrated Extension research. Between the years 2018 and 2023, the Alabama Pasture to Rail Program supported data collection on 667 calves through two different studies. Data collected in these studies are currently being used to update Extension recommendations on management strategies and potential of Alabama feeder calves. Feedback from facilitators and participants in these programs is often favorable for producer implementation but limitations are still faced by Extension personnel. A survey of county agents in Arkansas was recently conducted on programs such as Grass to Grid. Of the 45 agents that responded with active beef cattle programming in their county only 8% indicated that they had active participation in the Grass to Grid Program. An additional 13% of agents did indicate that they thought their county programming and producers would benefit from programming such as Grass to Grid. Limitations to the program were listed as market viability, producer buy in and turn-around results from the feedyard currently being used. Extension programming such as retained ownership programs have a place in helping producers build more sustainable programs. However, it is important to acknowledge the strengths, weaknesses and opportunities that must be addressed for producers and Extension personnel if they are to remain a function and useful tool.

First Report of Isolation and Characterization of Acanthamoeba spp. from the Milk Used for Calf Feeding.

Acanthamoeba spp. can be found in natural and artificial environments, which reflects their high adaptability to different conditions. Based on the available data, there is scarce information about the isolation of amoeba from milk. This study aimed to investigate the probable presence of Acanthamoeba in milk used for calf feeding. 200 milk samples from 50 industrial and traditional farms were collected. The samples were filtered and cultured on the 1.5% Non-nutrient agar medium. The amoebic growth was examined with an inverted microscope daily. DNA was extracted from the positive plates, and a PCR reaction was undertaken using the primers amplifying the Acanthamoeba 18S rRNA gene. Five samples were purified and sequenced using specific primers. Maximum likelihood reconstructions were performed using the phylogenetic program MEGA software. The osmo and thermotolerance of isolated trophozoites were examined as well. Out of 200 milk samples, Acanthamoeba was isolated from 27 (13.5%). The phylogenetic tree represents that all the isolates belonged to the genotype T4. Results of thermo and osmotolerance tests showed that isolates could develop at 37 and 43 ◦C. Besides, trophozoites survived at 0.5M mannitol and 1M. For the first time, Acanthamoeba spp. were isolated from milk used to feed dairy calves. Due to Acanthamoeba's neglected role in pathogen persistence and survival, hygiene instructions should be reconsidered.

Feeding time(s): Patient urgence and the careful temporalities of antimicrobial resistance

This paper seeks to understand how caring for new-born livestock is made possible, which practices of care are privileged and to what effect? These aims are situated in attempts to promote the prudent use of antibiotics amongst livestock farmers to prevent antimicrobial resistance. In focusing on the rearing of new-born calves on dairy and beef farms in England and Wales, the paper reveals how care is configured by different temporal orders, the tensions between different temporalities of care, the reasons for them and the strategies employed by calf rearers to manage these tensions. Drawing on the concept of the ‘timescape’, the paper shows how calf care temporalities are relationally enacted and configured by materials, infrastructures and technologies. Common (productivist) agricultural temporalities of care emphasise speed, urgency and efficiency. However, by analysing the practice of feeding colostrum and ‘tubing’ – the forced feeding of calves via a tube inserted into the oesophagus – we highlight how these rapid caring temporalities conflict with the slower, patient skills of calf rearing. At the same time, however, we show how care is rendered fluid as calf rearers find ways of accommodating seemingly discordant temporalities – what we call ‘patient urgence’ – allowing different temporalities to co-exist within agricultural timescapes. Nevertheless, we show how these practices of accommodation are themselves the result of a productivist temporal order that marginalises calves and calf rearers. We argue that these timescapes point to the need for broader structural and cultural changes within agriculture to reduce the use of antibiotics.

Growth performance, carcass traits, and feeder calf value of beef × Holstein and Holstein feedlot steers*

Growth performance, carcass traits, and feeder calf value of beef × Holstein and Holstein feedlot steers*

Effects of simplified group housing on behavior, welfare, growth performance, and health of preweaned dairy calves on a California dairy

Most US dairy calves are raised in individual hutches (IH) for biocontainment purposes and to facilitate monitoring and handling of calves. However, individual hutches typically restrict calves' activity and social interactions. Previous studies showed that group housing (GH) is beneficial to calf welfare and is associated with social benefits. The adoption of group housing (GH) on dairies is hindered by several concerns, with the primary concern being the potential for increased transmission of diseases due to heightened calf-to-calf contact. In light of this, our study aimed to compare the behavior, health, and growth outcomes of calves housed in groups of 3 to individually housed (IH) calves during the preweaning period. A total of 42 Holstein heifer calves on a commercial dairy in Northern California were enrolled in groups of 3 to different housing treatments; IH (n = 21) or GH (n = 21) between July and October 2020. Each treatment was composed of 7 groups of 3 calves each. Calves in the GH treatment were housed in groups of 3 from 6 to 10 d until 70 d of age. Individual pens consisted of one polyethylene hutch with a 1.5 m x 1.2 m outside exercise area. Group pens were constructed by assembling 3 polyethylene hutches with a 1.5 m x 3.6 m outside exercise area of wire panel fencing. Calves were weighed and measured for height at birth and weaning. Diarrhea and bovine respiratory disease (BRD) scores were recorded daily throughout the preweaning period. Cumulative incidence and hazard ratios were estimated for BRD and diarrhea for GH and IH. A Mixed model with pen as a random effect was specified to evaluate the effect of treatment. Group-housed calves gained 0.64 ± 0.02 kg/d while IH calves gained 0.65 ± 0.02 kg/d (P = 0.40). Similarly, there was no evidence for treatment differences in withers height gain in GH calves (0.22 ± 0.01cm/d) compared with IH calves (0.21 ± 0.01 cm/d) (P = 0.14). The cumulative incidence of BRD based on California scoring system in GH calves was 75 ± 9.68 compared with 66.66 ± 10.28% in IH calves (P = 0.73). Group-housed calves had a BRD hazard of 1.14 times that of IH calves (95% CI: 1.21-2.40; P = 0.74). The cumulative incidence of diarrhea (fecal score 3) in GH calves was 100% in comparison to 95.20 ± 4.66% in IH calves (P = 0.99). The mean proportion of scan observations of calves feeding on concentrates was significantly higher in GH (0.145 ± 0.004 per h) compared with IH calves (0.076 ± 0.003 per h) during the preweaning period (P < 0.001). The study results provide evidence that this simplified group housing system provides benefits of GH without detrimental short-term impacts during the preweaning period on calf growth and health.