Holstein Calves Research Articles

Genome assembly of a potential probiotic Bifidobacterium bifidum BB11 strain isolated from Holstein calves.

Here we report the genome sequence of Bifidobacterium bifidum BB11 strain, isolated from the Holstein bull calf's rumen samples. The strain tested positive for probiotic characteristics such as bile salt tolerance, adhesion, and acid tolerance. The genome size was 2,200,000 bp with the guanine and cytosine (G+C) content of 62.5%.

Dynamics of Blood Taurine Concentration and its Correlation with Nutritional and Physiological Status during the Fattening Period of Japanese Black Cattle.

Taurine, biosynthesized from methionine or cysteine in the liver, plays a crucial regulatory role in bile acid conjugation, antioxidant effects, and glucose and cholesterol metabolism. This may influence the metabolic changes associated with fat accumulation in beef cattle. However, the physiological role of taurine in this species has not been fully elucidated. In this study, we explored the physiological role of taurine in Japanese Black steers (Bos taurus) in different phases during the fattening period. To examine the correlation among plasma taurine concentrations, various physiological parameters, and genes related to taurine synthesis in the liver, we used biopsied liver tissues, blood samples, and rumen fluids collected from 21 steers at three different stages, i.e., early (T1; 13 months of age), middle (T2; 20 months of age), and late (T3; 28 months of age) phases. Additionally, to investigate the regulatory mechanisms underlying the expression profile of taurine synthesis genes, primary bovine hepatocytes obtained from 4-week-old Holstein calves were treated with palmitate, oleate, acetate, propionate, or β-hydroxybutyrate (BHBA). Plasma taurine and cholesterol concentrations significantly (P < 0.001) increased in the T2 phase, which is potentially attributable to increased energy intake and assimilation induced by increased intake of concentrated feed. Cysteine sulfinic acid decarboxylase (CSAD) expression significantly increased (P < 0.01) in T2 than in other phases. The expression levels of cysteine dioxygenase type 1 (CDO1) and cholesterol 7 alpha-hydroxylase (CYP7A1) were significantly higher (P < 0.001) in T2 than in T3; moreover, the CDO1/glutamate-cysteine ligase catalytic subunit (GCLC) ratio was higher (P < 0.05) in T2 than in T1. Plasma taurine concentrations were positively correlated with plasma methionine (r = 0.51; P < 0.05) and total cholesterol (r = 0.56; P < 0.05) concentrations at T2. Relative CDO1 mRNA expression was upregulated in cultured bovine hepatocytes treated with oleate and propionate, whereas it was downregulated upon acetate treatment. These findings indicate that the increase in plasma taurine concentrations in the T2 phase is associated with changes in lipid and methionine metabolism in Japanese Black steers.

Growth Performance and Microbial Activity Positively Responded to Interactive Effect of Nitrogen and Phosphorus in Young Holstein Dairy Calves.

We hypothesized that nitrogen (N) and phosphorus (P), as two pivotal nutrients that contributed to the growth of growing animals, may have interactive effect on growth performance and microbial development in young calves. For this purpose, feeding two starter protein contents (20% [20CP] vs. 24% [24CP], DM basis) and two phosphorus supplementation levels (0.35% [0.35P] and 0.70% [0.7P], DM basis) was evaluated on growth performance, health indicators, digestibility of nutrients and microbial protein synthesis (MPS), the latter estimated from urinary purine derivatives (PDs). Forty-eight female Holstein calves (3 days of age) were assigned randomly to the following treatments: 20CP-0.35P, 20CP-0.7P, 24CP-0.35P and 24CP-0.7P (n = 12, each). Milk feeding schedule was identical among treatments until weaning (d 59), but study lasted until d 73. Feeding 24CP compared to 20CP diet tended to improve starter intake, increased average daily gain (ADG) during pre-weaning period (p < 0.05), and final body weight (p = 0.01). Higher P supplementation has marginal effect on starter intake but improved ADG (pre-weaning; p = 0.02) and microbial activity by greater MPS (p = 0.02) compared to 0.35P. The greatest starter intake, the most favourable general appearance score, the highest withers height, the highest hip height, the greatest organic matter and neutral detergent digestibility, and the greatest MPS were found when calves fed diets contained 24CP along with 0.7P in starter. Based on the current study results, N and P have separate effects on the growth performance of young calves; however, their positive interaction can be attributable to growth performance and microbial development, especially during the pre-weaning period.

Effects of saccharomyces cerevisiae fermentation products on growth performance, fecal short chain fatty acids, and microbiota of pre-weaning calves.

This research aims to explore the effects of incorporating saccharomyces cerevisiae fermentation products (SCFP) on growth performance, nutrient digestibility, antioxidant capacity, fecal SCFAs, and microbial composition of pre-weaning calves. Twenty Holstein calves, 10 days old and weighing an average of 48.63±0.91 kg, were randomly assigned to either the control group (CON) or the SCFP group, with 10 calves in each group. The CON group received only a basal diet, while the SCFP group received the starter diet supplemented with 5 g/head/d of SCFP products (NutriTek, Diamond V Cedar Rapids, IA 52404, United States). The pre-trial period lasted for 5 days, followed by a main experimental period of 45 days. The SCFP group had significantly higher final weight, ADG, and FE compared to the control group (p < 0.05). Moreover, the SCFP group exhibited increased apparent digestibility of DM, CP, EE, ADF, Ca, and P (p < 0.05). Additionally, supplementation with SCFP led to elevated content of GH, IGF-1, and GLP-1 in serum. The inclusion of SCFP also raised serum CAT content and reduced serum MDA content in pre-weaning calves. Furthermore, SCFP supplementation influenced the composition of intestinal microflora by decreasing Actinobacteriota abundance and increasing the abundance of Ruminococcus, Lachnospiraceae_AC2044_group, Parabacteroides, and Butyricimonas. The addition of SCFP has a positive impact on the growth performance, nutrient digestibility, antioxidant capacity, and intestinal microflora composition of pre-weaning calves.

Combining single nucleotide polymorphisms and gene expression of LEP, FABP4, STAT5A and DGAT1 genes for improvement of body weight in Holstein calves

The objective of this study was to investigate the possible association of single nucleotide polymorphisms and gene expression of leptin (LEP), fatty acid binding protein (FABP4), signal transducer and activator of transcription 5A (STAT5A) and diacylglycerol acyltransferase (DGAT1) genes with body weight in Holstein calves. For the RNA extraction process, blood samples from 100 Holstein bull calves were taken. According to farm records, the acquired bull calves were weaned at a body weight of roughly 90 kg, with birth weights ranging from 31 to 38 kg and weaning ages ranging from 60 to 100 days. To account for the non-genetic causes, the dairy calves' body weight was changed to their 205-day body weight. Nucleotide sequence changes in the form of SNPs were found in the LEP, FABP4, STAT5A, and DGAT1 genes in the investigated Holstein calves. The identified SNPs and corrected 205-day body weight showed a significant correlation (P &lt; 0.05). According to ΔCT values, a significant relationship between the mRNA levels of the LEP, FABP4, STAT5A, and DGAT1 genes and body weight was also found (P &lt; 0.05). The effectiveness of the LEP, FABP4, STAT5A, and DGAT1 genes as proxies for growth qualities in Holstein dairy calves is highlighted by this study. Therefore, it was possible to select an animal with a high rate of growth.

Genetic parameters for direct and maternal genetic components of calving ease in Korean Holstein Cattle using animal models.

We investigated genetic parameters of calving ease (CE) using several animal models in Korean Holstein and searched for suitable models for routine evaluation of CE. Two phenotypic datasets of CE on first-parity Korean Holstein calves were prepared. DS5 and DS10 included at least 5 and 10 CE records per herd-year level and comprised 117,921 and 80,389 observations, respectively. The CE phenotypes ranged from 1 to 4, from a normal to extreme difficulty calving scale. The CE was defined as a trait of the calf. The BLUPF90+ software was used for (co)variances estimation through four animal models with a maternal effect (M1 to M4), where all models included effects of a fixed calf-sex, a fixed dam calving age (covariate), and one or more fixed contemporary group (CG) terms. The CG effects were different across models- a herd-year-season (M1, HYS), a herd-year and year-season (M2, HY+YS), a herd-year and season (M3, HY+S), and a herd and year-season (M4, H+YS). Direct heritability (h2) estimates of CE ranged from 0.005 to 0.234 across models and datasets. Maternal h2 values were low (0.001 to 0.090). Genetic correlations between direct and maternal effects were strongly negative to lowly positive (-0.814 to 0.078), further emphasizing its importance in CE evaluation models. These genetic parameter estimates also indicate slower future selection progress of CE in Korean Holsteins. The M1 fitted many levels with fewer observations per level deriving unreliable parameters, and the M4 did not account for confounded herd and animal structures. The M2 and M3 were deemed more realistic for implementation, and they were better able to account for data structure issues (incompleteness and confounding) than other models. As the pioneering study to employ animal models in Korean Holstein CE evaluation, our findings hold significant potential for this breed's future and routine evaluation development.

Birth Traits Associated with Pre-Adulthood Disease Manifestations in Calves.

The objective of this study was to explore the relationship between calf birth traits and their susceptibility to diseases before reaching adulthood. A total of 5253 birth traits of Chinese Holstein calves were examined, including gestation length (GL), calf weight at birth (CW), and calving ease score (CES), which ranges from 1 (easy) to 5 (very difficult). Furthermore, monthly medical records were scrutinized for pneumonia and diarrhea in these calves. The study assessed five aspects of disease manifestation in calves: age at first onset, frequency of illness, longest duration of treatment, and total duration of treatment. The link between age at onset and disease manifestation prior to adulthood was analyzed using general linear models and regression models. The GL of calves significantly correlated with the risk of pneumonia, with the risk decreasing as the GL increases. A higher CES was associated with a later onset of diarrhea in calves. Furthermore, the CES was significantly negatively correlated with the duration of diarrhea treatment in calves. These results suggest that implementing different preventive measures for calves with different birth traits and modifying treatment protocols for affected calves could enhance the productivity of dairy cows and reduce losses on farms.

Long-term effects of transition milk feeding on feed intake, growth performance, feeding behavior, and oxidative status of Holstein calves

This study investigated the long-term effects of feeding 5-d transition milk (TRANS) compared with milk replacer (MR) on parameters, including intake, growth, feeding behavior and oxidative stress. Fifty Holstein calves (30 females and 20 males) were fed either 12 L/day TRANS or MR for the first 5 d after an initial colostrum feeding of 3.5 L. Thereafter, all calves were fed with 12 L of MR/d (140 g/L) and were gradually weaned starting in wk 8 until wk 14. Throughout the 14 wk the calves had unrestricted access to concentrate (up to 9.8 kg/calf/day), hay, and water. After weaning all heifers were fed a total mixed ration for young cows. Oxidative status was assessed in blood samples from birth to first insemination. Parameters assessed included the ferric reducing ability of plasma (FRAP) for antioxidant capacity and the concentration of reactive oxygen metabolites by the dROM (detection of reactive oxygen metabolites) assay. In addition, the activity of glutathione peroxidase (GSH-Px), oxidative damage in the form of lipid peroxidation as thiobarbituric acid reactive substances (TBARS) and as advanced oxidation protein products (AOPP) were measured. An oxidative stress index (OSi) was calculated: dROM/FRAP x 100. Total protein (TP) concentration was also quantified via the Bradford assay. The only significant difference in feeding behavior between the 2 treatment groups was a higher concentrate intake by the TRANS calves during the weaning phase. Body weight and ADG did not differ significantly between the TRANS and MR groups. TRANS calves showed a trend for fewer cases of health disorders. Markers of oxidative status, including TBARS, AOPP, GSHPx, FRAP and ROM, showed no treatment effects but varied significantly over time. Of note, the oxidative stress index as ratio between pro- and antioxidants in both groups peaked during weaning and then returned to baseline, suggesting an effective response to this transition phase Overall, the results indicate that feeding TRANS during the first 5 d of life had no long-term effect on the parameters studied as compared with MR feeding under the present rearing conditions. These results provide insight into the changes of oxidative status with age and confirm that the relatively high milk feeding level, slow and late weaning enables calves to adapt well to solely solid feed.

Fatty acids promote migration of CD4+ T cells through calcium release-activated calcium modulator ORAI1 sensitive glycolysis in dairy cows

Nutritional and metabolic state in dairy cows are important determinants of the immune response. During the periparturient period, a state of negative energy balance in the cow increases plasma concentrations of fatty acids, which are associated with inflammation. Among immune cells, CD4+ T are able to function under high fatty acid (High-FA) conditions, but the underlying mechanisms regulating these events remain unclear. The objective of this study was to clarify the functional mechanisms of CD4+ T cells under High-FA conditions. Effects of glycolysis and calcium release-activated calcium modulator 1 (ORAI1) on migration of CD4+ T cells exposed to High-FA were investigated in vivo and in vitro. CD4+ T cells were isolated from peripheral blood of healthy (n = 9) and High-FA (n = 9) Holstein cows (average 2.5 ± 0.2 lactations, 12.3 ± 0.8 d in milk). In the first experiment, real-time quantitative PCR (RT-qPCR) was used to assess chemokine receptors in isolated CD4+ T cells and migration capacity. The relative mRNA measurements results revealed downregulation of CCR1 and CXCR2, and upregulation of CCR2, CCR4, CCR5, CCR7, CCR8, CCR10, CXCR1, CXCR3, CXCR4, CX3CR1. Among them, the expression of CXCR4 was relatively high. Therefore, CXCL12, a ligand chemokine of CXCR4, was an inducer of CD4+ T cell migration. CD4+ T cells were inoculated in the upper chamber and CXCL12 (100 ng/mL, Peprotech) in RPMI1640 was added to the lower chamber and transmigrate for 3 h at 37°C and 5% CO2. The cell migration assay revealed that migration capacity of CD4+ T cells from High-FA cows was greater. RT-qPCR indicated greater abundance of the glycolysis-related targets HIF1A, HK2, PKM2, Glut1, GAPDH, LDHA and Western blotting indicated greater abundance of the glycolysis-related targets HIF1A, HK2, PKM2, Glut1, GAPDH and LDHA in CD4+ T cells of High-FA cows. To characterize specific mechanisms of CD4+ T cell migration in vitro, cells from the spleens of 3 newborn healthy female Holstein calves were isolated (1 d old, 40-50 kg) after euthanasia. Inhibition of glycolysis attenuated the migration ability of cells, but had no effect on the protein and mRNA abundance of SOCE-associated ORAI1 and STIM1. In contrast, ORAI1 was upregulated in CD4+ T cells of cows exposed to high-FA. To explore the potential mechanisms whereby an active glycolytic metabolism affects CD4+ T cells under High-FA conditions, we knocked down ORAI1 (siORAI1) using small interfering RNA. Isolated CD4+ T cells from High-FA cows with the siORAI1 had an attenuated glycolytic metabolism and migration capacity. Taken together, these data suggested that calcium ions in CD4+ T cells from cows with High-FA regulate glycolytic metabolism and influence cell migration at least in part by modulating ORAI1. Thus, these studies identified a novel mechanism of Ca2+ regulation of CD4+ T cell glycolytic metabolism affecting their migration through the SOCE pathway.

Fat composition in milk replacer modulates plasma cholesterol of dairy calves

This study evaluated the effect of feeding milk replacers (MR) formulated with alternative fat sources and containing different fat compositions on plasma cholesterol of dairy calves. Forty-five individually housed male Holstein calves (2.3 ± 0.82 d; mean ± SD) were blocked by arrival day and age. Within each block, calves were randomly assigned to one of 3 treatments: 1) an MR containing a fat blend with 65% rapeseed and 35% coconut fats (RC), 2) an MR containing 65% palm and 35% coconut fat (PC), and 3) an MR containing 65% lard and 35% dairy cream (LD). All MR were isoenergetic with 30% fat, 25% protein, and 36% lactose (DM basis). Calves were fed 6.0 L/d from d 1 to 5, 7.0 L/d from d 6 to 9, and 8.0 L/d from d 10 to 35 at 13.5% solids. Water and chopped wheat straw were available ad libitum from arrival onwards. Milk, water, and straw intakes were recorded daily. Blood was sampled and BW was measured at arrival and weekly thereafter at 1300 h. Fecal scores were recorded daily after the morning meal. Growth and intakes did not differ among treatments. Plasma total cholesterol, high-density lipoprotein (HDL)-cholesterol, and low-density lipoprotein (LDL)-cholesterol concentrations were higher in calves fed RC than PC and LD, and higher in calves fed PC than LD. Additionally, plasma TG was greater in calves fed PC than LD at wk 2 after arrival, while calves fed RC did not differ from the other treatments. The proportion of abnormal fecal scores were reduced in calves fed RC in wk 2. Including palm and rapeseed fats in the MR did not affect growth but increased plasma total cholesterol.

Effect of Dietary Benzoic Acid Supplementation on Growth Performance, Rumen Fermentation, and Rumen Microbiota in Weaned Holstein Dairy Calves

Supplementation with benzoic acid (BA) in animal feed can reduce feeds’ acid-binding capacity, inhibit pathogenic bacterial growth, enhance nutrient digestion, and increase intestinal enzyme activities. This study aimed to investigate the effects of different doses of BA on the growth performance, rumen fermentation, and rumen microbiota of weaned Holstein dairy calves. Thirty-two Holstein calves at 60 days of age were randomly assigned into four groups (n = 8): a control group (fed with a basal diet without BA supplementation; CON group) and groups that were supplemented with 0.25% (LBA group), 0.50% (MBA group), and 0.75% (HBA group) BA to the basal diet (dry matter basis), respectively. The experiment lasted for 42 days, starting at 60 days of age and ending at 102 days of age, with weaning occurring at 67 days of age. Supplementation with BA linearly increased the average daily gain of the weaned dairy calves, which was significantly higher in the LBA, MBA, and HBA groups than that in the CON group. The average daily feed intake was quadratically increased with increasing BA supplementation, peaking in the MBA group. Supplementation with BA linearly decreased the feed-to-gain (F/G) ratio, but did not affect rumen fermentation parameters, except for the molar proportion of butyrate and iso-butyrate, which were linearly increased with the dose of BA supplementation. Compared with the CON group, the molar proportions of iso-butyrate in the LBA, MBA, and HBA groups and that of butyrate in the HBA group were significantly higher than those in the CON group. Supplementation with BA had no significant effect on the alpha and beta diversity of the rumen microbiota, but significantly increased the relative abundances of beneficial bacteria, such as Bifidobacterium, and reduced those of the harmful bacteria, such as unclassified_o__Gastranaerophilales and Oscillospiraceae_UCG-002, in the rumen. Functional prediction analysis using the MetaCyc database revealed significant variations in the pathways associated with glycolysis across groups, including the GLYCOLYSIS-TCA-GLYOX-BYPASS, GLYCOL-GLYOXDEG-PWY, and P105-PWY pathways. In conclusion, BA supplementation improved the composition and function of rumen microbiota, elevated the production of butyrate and iso-butyrate, and increased the growth performance of weaned Holstein dairy calves.

Fecal microbiota of diarrheic calves: Before, during, and after recovering from disease.

It is unknown if gastrointestinal dysbiosis in diarrheic calves causes disease or is a consequence of the disease. Describe the fecal microbiota of calves before, during, and after recovering from diarrhea. Fifteen female Holstein calves of 0 to 21 days old from a single farm. Seven calves remained healthy throughout the study, and 8 developed diarrhea on Day 14. Longitudinal cohort study. Microbiota composition was characterized by amplifying the V4 region of the 16S rRNA gene. Diversity (Shannon index) increased with age in healthy and diarrheic calves from Day 3 to 21, but diarrheic calves had a lower diversity on the day diarrhea was first observed (Day 14). By Day 21, diversity increased in calves that recovered from diarrhea and was not significantly different from that of their healthy counterparts (P > .05). Weighted UniFrac distance showed significant differences in the fecal microbiota between diarrheic and healthy calves at Day 14 of age (PERMANOVA, P < .05), but not before or after diarrhea (PERMANOVA, P > .05). Lactobacillus, Clostridium Sensu Stricto 1, and Collinsella were differentially abundant on Day 10 in calves that developed diarrhea on Day 14 (P < .05). The fecal microbiota of healthy and diarrheic calves evolved similarly during the first 10 days of age but differed significantly on the day of onset of diarrhea. Enriching Lactobacillus, Clostridium Sensu Stricto 1, and Collinsella before diarrhea onset could have been contributed to the development of diarrhea.

Performance and health status in preweaning semi-indoor holstein calves wearing calf jackets during winter months.

The purpose of this study was to investigate whether jacket wearing by semi-indoor Holstein calves affected performance, body measurements and health status in the preweaning period throughout the winter months. A total of one hundred calves were allocated into two treatment groups (control and jacket) in terms of their weights and sex. The calves throughout the study period were raised at individual calf hutches in a semi-open barn. All calves and the consumed concentrate intakes were weighed every 28 days to determine body weight (BW), average daily gain (ADG), total and daily feed consumption (TFC, DFC). Incidence rate (IR) ratios were calculated from the records of daily health assessments. Calves in treatment group were jacketed from first to 45 days of age. The weaning process started gradually at 56 days of age and the calves were weaned on day 63. No significant effects of wearing jackets in terms of body measurements and performance. The respiratory diseases IR was 1.15 times higher in calves without jackets, which means that calf health was positively affected by wearing jackets. The improved health status of the treatment group showed that wearing jackets may protect calves from adverse effects of cold stress. There is a need for more comprehensive studies about the effect of calf jackets in early periods of preweaning, especially in calves in outdoor hutches.

An organic zinc-chelating-peptide GQ-Zn supplementation ameliorates diarrhea through regulate gut microbiota and metabolites in pre-weaning Holstein calves

An organic zinc-chelating-peptide GQ-Zn supplementation ameliorates diarrhea through regulate gut microbiota and metabolites in pre-weaning Holstein calves

Does Pelleted Starter Feed Restriction and Provision of Total Mixed Ration Ad Libitum during Weaning Influence the Behavior of Dairy Calves?

Currently, in dairy farming, there is growing concern for the welfare of calves during the critical period between the separation from their dams and weaning. During weaning, rationed feeding is a practice used to improve feed efficiency and control the calves’ growth, but it could also have negative consequences associated with hunger and feed restriction behavior. One such consequence could be the performance by calves of stereotyped behaviors indicative of poor welfare, such as non-nutritive oral behaviors. We hypothesized that making a Total Mixed Ration (TMR) available to calves, in addition to the standard pelleted starter diet, thanks to its structural and nutritional characteristics, could help to focus the oral behavior of the subjects towards nutritional activities and therefore limit the development of stereotyped behaviors, even when the amount of starter is restricted. To test this hypothesis, 30 female Holstein calves (equipped with an accelerometer based on an ear tag), were randomly assigned to one of three treatments: a control diet (CTR) with an ad libitum calf starter but without TMR; Treatment 1 (TRT1) with both ad libitum calf starter and ad libitum TMR; Treatment 2 (TRT2) with ad libitum TMR and a restricted amount of a calf starter (50% of the intake starter of the control group day by day). All animals were kept in individual cages equipped with a slow-flow teat bucket apparatus for milk feeding and with access to separated buckets (one for drinking water, one for the starter, and one for the TMR) placed on the outside of the front gate of each cage. Sucking behavior, as well as resting, ruminating and activity behavior, was recorded individually from 7 days of life to weaning (63 d of age) by an automated monitoring system based on ear-tag accelerometers (SCR eSense, Allflex, Irving, TX, USA). The results showed that in the CTR group, there was a greater sucking activity compared to the TRT1 group (26.25 min/head/day vs. 16.83 min/head/day, p = 0.0181), while the TRT2 group showed intermediate values (20.41 min/head/day). We hypothesized that this increased sucking activity may be explained by the oral activity directed at sucking the Milk Bar tube observed only in CTR calves after complete consumption of available milk and could indicate a higher stress level than in the TRT1 group. The time spent resting was significantly lower for the CTR group compared to the TRT1 group (9.20 h/day vs. 11.15 h/day, p = 0.0049) while the TRT2 group was in an intermediate situation (10.65 h/day). Furthermore, the increase in time dedicated to rest observed in TRT1, in light of the good vitality of the calves shown by the daily patterns of resting behavior and daily activity, also seems to suggest an improvement in welfare conditions compared to calves receiving pelleted starter alone. Based on these results, we can deduce that providing TMR ad libitum in the diet of weaning calves could be an effective strategy to improve calf welfare due to the reduction in stereotyped oral activity. However, further studies are needed to establish threshold values useful for distinguishing physiological from pathological resting times in weaning calves raised in individual cages.

Calf immunization protocols with low-virulence isolates of Anaplasma marginale: Analysis of post-inoculation effects and protection against natural challenge

Bovine anaplasmosis is endemic and is of fundamental importance worldwide. Therefore, measures for controlling and preventing clinical diseases are warranted to ensure the reduction of associated economic losses. The objective of the present study was to assess the post-inoculation effects and protection conferred by three different protocols of inoculation of low-virulence live strains of Anaplasma marginale (UFMG1 and UFMG3) in field-challenged cattle. Sixty-eight Holstein calves with an average age of 17 days were randomly divided into four groups. The groups received two subcutaneous administrations spaced 40 days apart, at a dosage of 2 × 106 infected erythrocytes of the following A. marginale strains: G1 (UFMG1 + UFMG1); G2 (UFMG3 + UFMG3); G3 (UFMG1 + UFMG3); and G4 (control). Every two days, the animals were evaluated for rectal temperature, Packed Cell Volume (PCV), and blood smears. Blood samples were collected prior to inoculation, before the field challenge, and after the challenge period, nPCR and IFAT techniques were performed. There were no significant differences in rickettsemia levels, reduction in PCV, or antibody detection among the different inoculation strategies. Forty days after the second inoculation, 90 %, 84.6 %, and 90.9 % of the animals in G1, G2, and G3, respectively, tested positive using nPCR. After inoculation, the group G2, which received the UFMG3 inoculum, had a higher frequency of treatment (odds ratio of 6.7; 1.198-38.018 CI; p = 0.03), while groups G1 and G3 demonstrated similar treatment frequencies compared to the control. During the natural challenge phase, 13.3 % of animals in group G1 required treatment (odds ratio of 0.108; 0.018-0.635 CI; p = 0.014) compared to 58.8 % of the control group. Considering the results collectively, the protocol using the UFMG1 strain (G1) stands out for its potential to be safe and induce some degree of immunization against A. marginale, reducing the incidence of clinical disease and the need for treatment during natural challenge.

Establishment of methanogen bacterial interactions during the preweaning period of dairy cattle

Ruminant livestock are major contributors to anthropogenic methane emissions in the United States and worldwide. Enteric methane is generated by methanogenic archaea residing in ruminant digestive tracts. Information on when methanogens colonize the gut and when they begin to interact with bacteria during the early phases of the ruminant life cycle is less explored. The objectives of this study were (i) to investigate the composition of the methanogenic archaeal community at birth and through the weaning transition and (ii) to determine if and when the methanogenic archaea begin to interact with bacteria in the lower gut of neonatal dairy calves. Ten female Holstein calves (approximately 45kg birth weight) were enrolled in the study. Fecal samples were collected every two weeks (Wk 2, 4, 6, 8, 10, and 12) between birth and weaning and analyzed for methanogenic archaeal diversity via 16S rRNA amplicon sequencing and quantitative real-time PCR (RT-qPCR). Estimates of alpha diversity (Observed species, and Shannon diversity index) and beta diversity (weighted and unweighted UniFrac distances) showed significant differences (P &lt; 0.05) between archaeal communities across timepoints. Both 16S rRNA amplicon sequencing and RT-qPCR analyses revealed Methanobrevibacter was the most prevalent genus at Wk2, Wk4, and Wk6, whereas Methanosphaera gradually increased with time and was most abundant at Wk10 and Wk12. Correlation analysis revealed that Methanobrevibacter and Methanosphaera were inversely correlated with each other and formed distinct cohorts with specific bacterial lineages similar to those reported in the mature rumen, thus revealing that these associations are established during the preweaning period. Therefore, the preweaning period presents a window of opportunity to interfere with early-life methanogenic colonization with the ultimate goal of reducing enteric methane emissions without perturbing ruminal function later in the life of dairy cattle.

The Effects of Restricted and Ad Libitum Milk Feeding on Growth and Health of Calves

In recent years, there has been a growing concern among consumers regarding animal welfare and their requirements, leading to an increased interest in exploring new approaches to calf rearing. Therefore, the aim of this study was to investigate the effects of milk feeding levels on the growth, feed intake, and blood variables of group-raised calves during the suckling period. Ten Holstein calves, 5 in each group, were used in the study when they were five years old. The calves were acclimated to an automated feeder during the initial 19 days of the experiment, and their initial LWs were recorded after weighing them again. The study concluded upon weaning the calves when they were sixty years old, with a total duration of 36 days The calves in the first group (G1) were provided with a total of 4 L/day of milk replacer, divided into 2 L servings in the morning and evening. Conversely, calves in the second group (G2) were allowed a maximum intake of 12 L/day of milk replacer, mimicking the natural sucking behaviour, with feedings in the morning (05:00-08:00), midday (10:00-13:00), and evening (16:00-20:00). Despite no significant differences in the LW, total and daily LW gains, and body measurements averages between of the groups, calves in G1 consumed more starter feed compared to those in G2 (P

509 Growth and health of Holstein and Holstein x Angus calves from birth to the end of the grower phase

Abstract Feedlot growth performance and carcass traits often differ between Holstein and dairy-beef crossbred calves. However, little is known about their performance and health during the growing phase when reared under similar conditions. This study aimed to compare purebred Holstein (n = 20) and Holstein x Angus crossbred (n = 20) steers from birth until the end of the grower phase. Male calves sourced from one commercial farm arrived at a calf rearing facility at 4.7 ± 1.94 d of age. Calves were fed milk replacer (24 % CP, 20% fat) twice daily at 12 % of birth body weight (BW) for the first 2 wk after arrival and 15 % BW thereafter until wk 6. Calves were gradually weaned from wk 7 to 9. Calves were offered starter (21 % CP, 28% starch) ad libitum until wk 12, and were fed a grower diet (15 % CP, 56 % starch) until wk 32. Milk intake was recorded daily and starter intake on a weekly basis. Once on the growing diet, feed intake was recorded daily using automated feed bins (Roughage Intake Control system, Hokofarm Group). Until wk 12, fecal and respiratory scores were recorded twice daily to estimate the incidence of disease, BW was measured weekly and frame measurements (hip and wither heights, and heart and chest girth) were recorded on wk 4, 7 and 12. From wk 12 to 32, BW and frame measurements were recorded monthly. Data were analyzed using PROC GLIMMIX (SAS 9.4), with breed as fixed, and calf and time as random effects. There were no differences between breeds in initial BW (P = 0.69), proportion of days with diarrhea (P = 0.21) or respiratory disease (P = 0.11), intake of milk (P = 0.45), starter (P = 0.83) or grower diet (P = 0.28). Crossbred calves tended to have greater average daily gain during the rearing phase (P = 0.07) and were growing 250 g/d faster than Holstein calves throughout the growing phase (P &amp;lt; 0.01). Thus, at the end of the growing phase, crossbred calves were 33.5 kg heavier than Holstein calves and had a better feed conversion rate (P &amp;lt; 0.01). During the growing phase, crossbred calves had larger heart and chest girths (P &amp;lt; 0.01) than Holstein calves, whereas hip and wither heights were higher (P &amp;lt; 0.01) for Holstein calves throughout the study. Overall, crossbred calves had greater average daily gain and improved feed conversion rate than Holstein calves during the growing phase, but it remains unknown if these differences will affect their feedlot performance.

480 The effect of parity on the quality of colostrum, internal parasite load, and postnatal development of Holstein calves

Abstract This research aimed to associate the effect of the parity number of the mother on the transfer of immunity, internal parasite load, and weaning weight of the female progeny. Calves that receive sufficient and good quality colostrum shortly after birth present improved passive immunity, vital for optimum calf health and future production. Management practices and the parity of the dam can influence colostrum composition, leading to an unsuccessful transfer of passive immunity and an increased incidence of infectious agents, which increases diarrhea and, thus, morbidity or mortality in newborn calves. The study included 90 animals, Holstein cows and their female progeny that were distributed into three groups according to the dam parity: first (n = 15 + 15), second (n = 15 + 15), and third (n = 15 + 15) parity. Immediately after birth, birth weight was recorded, and colostrum immunoglobulins (IgG) were determined by colostrometer and refractometry. The chemical composition (fat, protein, and non-fat solids) of the colostrum was determined using a milk analyzer (Ekomilk, Milkana KAM 98-2A, Satara Maharashtra) according to the manufacturer for cow milk. The calves consumed 10% of their birth weight of colostrum from their respective mother. Fecal samples were collected at 0 and 30 d of age and assessed for internal parasites (coccidia). Our preliminary results indicate that calves from dams from third parity were heavier at birth (P &amp;lt; 0.001; Table 1). The specific gravity of the bovine colostrum was similar among groups (P &amp;gt; 0.05). IgG concentration in colostrum tended to differ among groups by the refractometry (P = 0.08; Table 1), but not by colostrometer (P &amp;gt; 0.05; Table 1). The density and protein content in colostrum differed among groups, favoring dams from third parity (P &amp;lt; 0.05; Table 1). Fat content in colostrum was greater in dams from first parity (P &amp;lt; 0.01; Table 1); but not non-fat solids (P &amp;gt; 0.05; Table 1). The internal parasite load and incidence of coccidia at 30 d of age did not differ among groups (P &amp;gt; 0.05). Our preliminary conclusions indicate that the fat content in colostrum was greater in first-parity dams than in third-parity dams, perhaps due to a dilution effect. The difference in birth weight is possibly due to maternal body weight. The greater weight at birth, IgG content in colostrum and the better colostrum quality from third-parity dams led to healthier calves at 30 d of age. More research is needed to elucidate if these conditions remain up to weaning and in their first insemination.