Adequate colostrum intake is critical for the passive transfer of immunity in calves, and serum γ-glutamyltransferase (GGT; EC 2.3.2.2) is a potential indicator. However, conventional assays for its detection require laboratory facilities, limiting their use in the field. Herein, a simple visual test has been developed for the semi-quantitative determination of serum GGT using immobilized reagents on paper supports. The enzyme substrate, drop volume, and membrane type were optimized, with γ-L-glutamyl-3-carboxy-4-nitroanilide, 10 µL drop volume, and a binder-free microfiber glass membrane providing the best performance. The visual test showed a limit of semi-quantification (LOSQ) of 39 U/L, while digital analysis slightly improved the sensitivity. When applied to calf serum samples, the test reliably reflected GGT evolution: negligible at birth, peak activity at 2 days (corresponding to colostrum intake), declining by day 14, and further decreasing at day 18. The visual test showed strong agreement with the conventional enzyme assay (κ = 0.94), correctly estimating 26 out of 31 samples (84 %), and digital analysis of the membranes correlated even more closely (R = 0.9924). This point-of-need (PON) device offers a rapid, low-cost, and practical tool for on-farm monitoring of colostrum intake, supporting early detection of failure of transfer of passive immunity (FTPI) and improved calf health management.

Fecal lactoferrin and fecal calprotectin have been proposed as biomarkers of intestinal inflammation in several animal species. The main objectives of this work were to validate an analytical procedure for the measurement of lactoferrin in calf feces, to study the correlation between lactoferrin and calprotectin concentrations, and to evaluate the influence of fecal water content in the determination of these proteins. This knowledge is essential for effectively using these biomarkers in young calves exposed to inflammatory gastrointestinal diseases.Seventyeight male Holstein dairy calves between two and three weeks of age were included in the study. Lactoferrin was determined with a bovine milk lactoferrin ELISA kit and calprotectin was measured using a human immunoturbidimetric method previously validated in bovine feces. Analytical validation of the lactoferrin assay achieved good results, with intra and inter assay CV < 10 %, recovery rates between 80 and 120 %, and optimal linearity under dilution. A robust correlation was observed between fecal calprotectin concentrations in dry and wet feces (r = 0.903), while a moderate correlation was observed for fecal lactoferrin concentrations (r = 0.648). Correlation between both biomarkers was moderate in fresh feces (r = 0.514) as well as in dry feces (r = 0.561). In conclusion, the lactoferrin ELISA kit is valid for its use with calf fecal samples, both biomarkers showed a moderate correlation between them, and fecal lactoferrin concentration is more influenced by feces moisture than fecal calprotectin concentration.

Fecal biomarkers are becoming an important analytical tool since feces are in direct contact with the inflamed intestine and site for the gut microbiome. The objective of this study was the identification of differential fecal metabolites by means of 1H-NMR to evaluate the management of male dairy beef calves, and which could become potential biomarkers of gastrointestinal disorders. Holstein calves were subjected to a protocol aimed to simulate real conditions of the dairy beef market. Three groups were studied: Control (CTR: high colostrum, no transport, milk replacer), LCMR (low colostrum, transport, milk replacer) and LCRS (low colostrum, transport, rehydrating solution). Fecal lactoferrin was determined as marker of intestinal inflammation, and metabolomic profiling was performed in feces collected the day after arrival to the farm. 41 polar and 10 non-polar metabolites were identified, of which proline, formate and creatine increased in the LCRS group, whereas butyrate and uracil decreased. Less differences were found in non-polar metabolites. Multivariate analysis indicated that most differences are found between the LCRS group and the others. In conclusion, this study indicates that feed restriction has a more important effect at this age than colostrum uptake and transport. These results should help to identify robust fecal biomarkers to assess calf intestinal health and improve management protocols.

The aim of this study is to assess the environmental impact from the Catalan (North-Eastern Spain) feed production intended for beef farms with the focus on the ingredients and their geographical origin, as it holds the greatest weight on the environmental impact. To assess the environmental footprint of the Catalan feed production for the year of reference (2023), feed mills with the greatest production rates were identified. This allowed for a representation of a 46% of the total of this type of feed produced in Catalonia. An average feed formula was calculated for each production phase and feed mill, and the geographical origin of the ingredients was considered to differentiate the impact from regional practices and production rates. This aspect is also important in the case of the water footprint, as sensitivity to the impact depends on the water availability of the region. Functional unit was 1 kg of feed product at feed mill entry gate. Scope included impact from feed ingredients production and transport to the feed mill. This abstract focusses on the carbon (CC) and water footprint (WF) assessed using EF 3.1 (EC, 2021). Secondary datasets used were from Ecoinvent v3.9 and Agribalyse 3.1.1. The footprint from an average European feed (PEFCR 2024) was calculated with the same criteria as the rest of the Catalan feed. Catalan weighted (by production rates) beef feed footprints (Table 1) were in the same order of magnitude than the average European results (CC: 1.36 kg CO2eq; WF: 3.49 m3eq). However, individual feed mill average footprints (Figure 1) showed large data spread in some phases, including some atypical values, which suggests margin for improvement. Drivers of environmental impact included: i) high inclusion rates, mostly cereals like barley; ii) specific production practices in origin, like deforestation processes linked to soy production (Brazil, or Argentina). Irrigated crops such as maize coming from Ukraine were critical. Also crops that are mostly rainfed but with a small occurrence of irrigation greatly contributed to the WF (e.g.: wheat) because of coming from water deprived regions like Spain. Spanish rice was another of the hotspots. Simply reducing the critical ingredient in the formula might just trade the impact to another source. Using geographical origins with better production rates or less impactful practices or using irrigated crops from areas with lower water deficit, can reduce CC and WF, overcoming the potential increase in impact from transport. Transport accounted for less than a third of the footprint in most cases, and its impact depends on the means of transportation, not only on the distance. Overall, solutions need to be addressed considering areas less sensitive to impact and with less impactful practices, while maintaining the nutritional balance, production rates and animal wellbeing.

Water availability is a local issue of growing importance in Mediterranean areas where water scarcity linked to climate change and population growth is already leading to increased competition for this resource. This study is aimed at the following: (i) assessing the water-related environmental impacts (water use, freshwater ecotoxicity and eutrophication, marine eutrophication, acidification, human toxicity, and ionizing radiation) along the production chain of cow milk in Catalonia, northeastern Spain; and (ii) addressing the issues encountered (modelling choices, data gaps and inconsistencies) which t can affect the quality of results when performing a water-footprint comprehensive assessment, focusing on water use and associated water scarcity impacts. The scope included the process from the extraction of raw materials up to the distribution of the packaged fat- and protein-corrected milk to the distribution centres of the supermarket chains and markets. Results showed the farm stage to be determinant (contributing to over 60% of the impact), due to the impact of feed production. Impact results were in the range of the European benchmark given by the Product Environmental Footprint Category Rules for dairy products, except for the water scarcity footprint which was one order of magnitude larger than the reference value, due to water scarcity in Spain. Considering compound feed ingredients with a lower water scarcity footprint, and research into slurry treatment for its use as irrigation and cleaning water (without compromising safety and health) could help reduce this impact. Water accounting and traceability along the production chain could support the dairy industry to take responsibility for the consequences of their production choices.

Abstract The aim of this study was to evaluate the effect of dietary straw withdrawal in high-concentrate diets on efficiency, carcass performance, rumen characteristics and seized livers in dairy beef crossbred bulls housed with straw bedding. Bulls [n = 93; 335 ± 9.0 kg body weight (BW); 218 ± 4.0 d age] were group-housed in 6 straw-bedded pens according to 3 different feeding programs (2 pens/treatment): 1) CTR (n = 32), concentrate (13.1% CP, 5.9% fat content, 16.1% NDF, 40.8% starch content) and straw ad libitum fed in two separate feeders; 2) TSW (n = 32), like CTR, however, dietary straw withdrawal took place the first 84 study days; and 3) NSS (n = 29), concentrate with a reduced starch content (12.2% CP, 4.6% fat content, 22.0% NDF, 39.6% starch content) without dietary straw for the whole study. The study lasted 155 d divided into eleven 14-d periods. Individual concentrate intake was recorded daily, and dietary straw consumption was recorded per pen biweekly, as was individual BW. Carcass performance, rumen characteristics and seized organs were recorded at the slaughterhouse. Data were analyzed with a mixed-effects model. The first period was an adaptation where a dietary straw bale per pen was offered in all treatments; thereafter, only in CTR, and in TSW, after period 6. Treatment by period interactions (P < 0.01) in efficiency parameters were observed. Specifically, BW was greater in CTR than in TSW and NSS bulls while straw withdrawal periods; however, TSW bulls increased BW compared with NSS bulls when dietary straw was reintroduced, with final BW greater in CTR and TSW than in NSS bulls (569, 557 and 536 ± 8.0 kg, respectively). Regarding feed consumption, while dietary straw withdrawal for the first 6 periods, concentrate and straw intake were less in TSW and NSS than in CTR bulls, regardless the type of concentrate; after period 7, concentrate intake did not differ among treatments, and straw intake was greater in CTR and TSW than in NSS bulls, except in period 7, just after dietary straw reintroduction, that was greater in TSW than in CTR bulls. Hot carcass weight was greater (P < 0.01) in CTR than in TSW and NSS bulls (314, 296 and 299 ± 6.0 kg, respectively); dressing percentage was greater (P < 0.01) in CTR and NSS than in TSW bulls (55.1, 55.9 and 53.2 ± 0.65%, respectively); and carcass conformation tended (P = 0.06) to have greater classification in CTR bulls, and reduced classification in TSW bulls. Number of sized livers tended (P = 0.07) to be greater in NSS than in CTR and TSW bulls (22, 3 and 9%, respectively). In conclusion, short and long-term dietary straw withdrawal decreased animal and carcass performance regardless concentrate’s starch content in dairy beef crossbred bulls fed high-concentrate diets housed with straw bedding.

Abstract Calf recovery after arrival at the rearing farm in unweaned calves is impaired by periods of stress, feed restriction and fasting during marketing and transportation. The use of feed additives to enhance intake at arrival could be a strategy to minimize those negative effects. A total of 72 calves (71.4 ± 1.72 kg) gathered in a commercial assembly center and transported 9 h to a rearing farm were used to evaluate the effect of a sensory additive (SA) on performance in calves fed 2 L of milk replacer twice daily at 12.5% and ad libitum concentrate feed. Calves were allocated in 8 pens and distributed in 2 treatments (4 pens/treatment): calves fed a concentrate without SA since the beginning of the study (arrival to the rearing farm after transport) until weaning (CON; n = 36); calves fed a concentrate containing SA (SEN; n = 36) from arrival until weaning. Calf body weight (BW) and pen intake were recorded weekly. On d 21 of the study, calves were partially weaned and only milk replacer was offered in the morning, and on d 28 all calves were completely weaned. The study lasted 35 d. Data were analyzed with a mixed-effects model. Average daily gain was greater (P = 0.04) for SEN calves compared with CON calves (0.68 ± 0.019 kg/d and 0.61 ± 0.019 kg/d, respectively). Final BW of SEN calves (95.5 ± 0.89 kg) tended (P = 0.06) to be greater compared with BW of CON calves (93.1 ± 0.89 kg). Finally, average concentrate intake was greater for SEN calves (0.89 ± 0.023 kg/d) compared with CON calves (0.79 ± 0.023 kg/d). Unweaned dairy beef calves receiving sensory additive improved concentrate intake and growth at farm arrival improving their recovery.

Abstract Data from 347 unweaned male dairy beef calves enrolled in 3 studies from 2021 to 2023 were used to evaluate the impact of transport or entire commercialization (marketing and transport) on performance recovery [average daily gain (ADG) and concentrate intake (CI)] and biomarkers of energy balance [non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), and glucose] and gastrointestinal functionality [gut permeability (Cr-EDTA) and enterocyte mass (citrulline)] at farm arrival. Calves were distributed in 3 treatments according to the different managements subjected in the previous studies: calves from a sole dairy farm that were not fasted neither transported (CTR), calves from a sole dairy farm that were transported and fasted for 19 h (TRA), and multi-origin calves commercially marketed and transported for 9 h (COM). On arrival at the rearing farm (d 0), calves were allocated individually, and body weight (BW) was recorded. Calves were fed milk replacer twice daily, and they had ad libitum access to concentrate and water. Concentrate (CI) and milk replacer intake were recorded daily, and BW and the biomarkers of energy balance and gut dysfunction were obtained on d 0 (arrival), 1, 2, and 7. Data were analyzed with mixed models. An interaction (P < 0.01) between treatment and time was observed for CI. On d 0 CTR and TRA had similar CI, while COM had the least CI. On d 1, all treatments decreased CI except CTR. While TRA recovered CI to CTR levels, COM had 50% less CI compared with the other calves on d 7. The COM calves had the least (P < 0.01) ADG compared with CTR and TRA calves. On d 0, COM calves had greater (P < 0.01) concentrations of NEFA and BHB compared with TRA and CTR, and TRA greater (P < 0.01) than CTR calves. The COM calves did not recover NEFA and BHB basal concentrations by d 7 as observed in TRA calves. Concentration of Cr-EDTA was greater on d 0 for TRA calves compared with CTR and COM calves, however concentration of Cr-EDTA was greater during the first 7 d in COM calves compared with CTR and TRA calves. Finally, citrulline concentration was less in COM calves compared with CTR and TRA calves independently of the sampling day. The entire commercialization process, marketing and transportation, of unweaned dairy beef calves impairs intake recovery and growth, and these results are aligned with negative energy balance and comprised gastrointestinal functionality at farm arrival.

Alternative water disinfectants to chlorination need to be identified because its effectiveness is limited by water pH and potentially carcinogen by-products resulted from chlorination and organic compound reaction. The first study aimed to evaluate the effect of different drinking water chemical disinfection treatments on water quality, its potential hazard effects on animal health, water and feed consumption, and apparent total tract digestibility in dairy beef bulls fed high-concentrate diets. For 224 days, 24 Holstein bulls (176 +/- 16.3 kg BW, and 149 +/- 5.8 days of age) were individually assigned to one of four treatments with different drinking water chemical disinfectants: without disinfection (CTR); acidification and chlorination (ACCHL; 0.65 mL/L H3PO4 and 0.14 mL/L NaClO 15%); hydrogen peroxide (PER; 0.15 mL/ L); and chlorine dioxide (DIO; 2.50 mL/L). Data were analysed with a mixed-effects model. Treatments affected the chemical characteristics of the water: in ACCHL, pH was 6.60 and free residual chlorine was 0.75 mg/L; in PER, H2O2 was 10.6 mg/L; and in DIO, ClO2 was 0.52 mg/L. Water physicochemical quality parameters in all treatments were below maximal thresholds established for safe water consumption by the Water Safety Royal Decree (RD 140/2003). In addition, the total coliform count of treated waters was reduced (P = 0.01) compared with CTR; moreover, ACCHL and DIO treatments were more effective in reducing total coliform count than PER. Dry matter intake tended (P = 0.07) to increase in DIO compared with CTR. Treatments did not affect blood parameters nor apparent total tract digestibility. The second study aimed to evaluate the potential benefit on animal performance of two drinking water disinfectants under commercial conditions in dairy beef crossbred Holstein bulls fed high-concentrate diets. Ninety-six animals (307 +/- 4.4 kg BW, and 224 +/- 1.8 days of age) were allocated to six pens for 140 days and assigned to one of two treatments: ACCHL, most common water disinfectant, and DIO. Data were analysed with a mixed-effects model. Water total coliform count and water consumption were similar between treatments. Concentrate intake was greater (P = 0.02) in ACCHL for the last 14 study days. Growth performance and carcass quality were similar between treatments. In summary, acidification and chlorination, H2O2, and ClO2 as drinking water disinfectants in dairy beef bulls had good disinfecting activity without detrimental effects on health and nutrient digestibility, and performance. (c) 2024 Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract The aim of this study was to evaluate the effect of dietary straw withdrawal in high-concentrate diets on animal behavior in dairy beef crossbred bulls housed with straw bedding. Bulls [n = 93; body weight (BW) = 335 ± 9.0 kg, and 218 ± 4.0 d of age) were group-housed in a partially opened barn with 6 pens straw-bedded cleaned every 2 wk. Animals were assigned to one of 3 different feed programs: 1) CTR (n = 32), concentrate (13.1% crude protein (CP), 5.9% fat content, 16.1% neutral detergent fiber (NDF), 40.8% starch content) and straw ad libitum fed in two separate feeders; 2) TSW (n = 32), like CTR; however, dietary straw withdrawal took place the first 84 study days; and 3) NSS (n = 29), concentrate with a lower starch content (12.2% CP, 4.6% fat content, 22.0% NDF, 39.6% starch content) without a dietary straw for the whole study. The study lasted 155 d divided into eleven 14-d periods. General activities and postures were recorded through scan sampling every 5 min, and social behavior was recorded during 5 min of continuous sampling in two rounds of 15 min. Social behaviors were transformed to a log scale to achieve a normal distribution. Data were analyzed with a mixed-effects model. The first period was an adaptation where a dietary straw bale per pen was offered in all treatments; thereafter, only in CTR, and in TSW after period 6. Percentage of bulls eating at the concentrate feeder was greater (P = 0.05) in NSS than in CTR and TRW (5.87 vs. 4.64 and 4.82 ± 0.038 %, respectively). The percentages of bulls ruminating at the beginning of the study were greater (P < 0.01) in CTR compared with TSW and NSS, but after dietary straw was offered in TSW, the percentages of bulls ruminating increased in TSW and were greater in CTR and TSW than in NSS. At the beginning of the study, during the dietary straw withdrawal in TSW bulls, the number of oral behaviors and stereotypies were greater (P < 0.01) in TSW than in CTR, but after straw offer in TSW oral behaviors and stereotypies were only greater in NSS than in CTR and TSW. In conclusion, short- and long-term dietary straw withdrawal increased behaviors indicative of poor animal welfare regardless of the starch content in the concentrate in dairy beef crossbred bulls fed high-concentrate diet housed with straw bedding.

Abstract Pneumonia is the main health issue that farmers have to fight when calves arrive at the rearing farm after marketing and transportation. Calves with pneumonia have a low intake impairing the recovery at arrival. The use of additives to enhance intake and immunity at arrival could be a strategy to minimize those negative effects. A total of 36 calves [body weight (BW) = 71.3 ± 2.83 kg] with pneumonia (ultrasound lung score ≥ 3) arriving at a commercial farm after marketing and transportation were used to evaluate the effect of a mixture of feed additives (FA) comprising a palatability enhancer, standardized olive pomace extract and tributyrin on performance in calves fed 2 L of MR twice daily at 12.5% and ad libitum concentrate feed. Calves were allocated in 4 pens and distributed in 2 treatments (2 pens/treatment); calves fed a concentrate feed without FA since the beginning of the study (arrival to the rearing farm after transport) until weaning (CT; n = 18); calves fed a concentrate feed containing the mixture of FA (CM; n = 18) from arrival until weaning. Calf BW and pen intake were recorded weekly. On d 21 of the study, calves were partially weaned and only milk replacer was offered in the morning, and on d 28 all calves were completely weaned. The study lasted 35 d. Data were analyzed with a mixed-effects model. Final BW of CM calves (95.9 ± 1.29 kg) tended to be greater (P = 0.08) compared with BW of CT calves (92.7 ± 1.29 kg). The CM calves tended (P = 0.06) to have greater ADG than CT calves (0.70 ± 0.037 kg/d and 0.61 ± 0.037 kg/d, respectively). However, a greater sample size may be necessary to observe differences in average concentrate intake measured by pen between treatments (0.82 ± 0.033 kg/d and 0.87 ± 0.033 kg/d for CT and CM, respectively). These results highlight the potential of using a mixture of feed additives with olive pomace extract, palatability enhancers, and tributyrin on the performance recovery of calves with pneumonia on arrival at the rearing farm.

The present study aimed to evaluate the potential hazardous effects of NO3− concentration in drinking water on health, feed intake, rumen fermentation and microbiota, and nitrogen excretion of Holstein heifers fed a high-concentrate diet for a sustainable water use. Twenty-four Holstein heifers were individually allocated and assigned to one of four treatments with increasing drinking water NO3− concentration: CTR, without NO3−; LOW, with 44 mg NO3−/L; MOD, with 110 mg NO3−/L; and HIGH, with 220 mg NO3−/L. The entire study lasted 168 days. Fortnightly water NO3− concentration and daily feed and water intake were recorded. Blood parameters, rumen pH, volatile fatty acids, NO3− and NO2− concentration, microbiota, and apparent total tract digestibility were determined at the beginning and at the end of the study. Most of the analyzed parameters were similar among treatments. Denitrifying bacteria population, estimated as nosZ gene copies, were greater in HIGH animals than in CTR animals at the end of the study. In conclusion, drinking water NO3− concentration up to 220 mg/L has no detrimental effect on health, feed intake, rumen fermentation, nor N excretion in dairy beef cattle for periods up to 168 days; moreover, denitrifying bacteria population increased, which are related with the neutralization of the greenhouse gas N2O.

Abstract The aim of this study was to evaluate the rumen in vitro methane (CH4) production of concentrates feed with a different protein source (PS) replacing partially palm oil by different seeds (SE) rich in polyunsaturated fatty acids (PUFA). Concentrate PS were: T1 = 8% soybean meal; and T2 = 15% dried distillers grain. Palm oil (CTR; 4% and 3.5% for T1 and T2, respectively) was partially substituted (1%) by flax seed (FL; 2.7%), canola seed (CO; 3%) or sunflower seed (SU; 2.3%), thus 8 concentrates were tested. Samples were ground at 1-mm and used in an in vitro digestibility assay. The rumen liquid was obtained at the slaughterhouse. Two incubation sets were done; two sampling points lasted 24 and 48 h to calculate the dry matter (DM) digestibility; a third sampling point lasted 12 d to monitor the CH4 production. Data were analyzed using a mixed effects model. Net volume of CH4 per degraded DM presented a PS effect (P < 0.01); T1 produced greater net volume of CH4 per degraded DM than T2 (8.12 vs. 6.91 ± 0.330 ml/mg, respectively). Furthermore, net volume of CH4 per degraded DM presented a SE effect (P < 0.01); all concentrates with seeds tested reduced the net volume of CH4 per degraded DM compared with CTR, and specifically CO produced lower net volume of CH4 per degraded DM than FL and SU (8.91, 7.47, 6.28, 7.39 ± 0.467 ml/mg; CTR, FL, CO, SU, respectively). In conclusion, the use of flax, canola, or sunflower seeds to partially substitute palm oil in concentrate feed, regardless of its PS, can be potential strategies to reduce rumen CH4 emissions, and seems that canola seed may be the most effective one.

Abstract This study examined the interactions between early life nutrition strategies and their impact on growth, development, and fecal consistency in surplus bull calves. Holstein-Friesian bull calves [n = 120; body weight (BW) = 43.1±3.56 kg] were enrolled. In the first 12 h after birth, calves were fed either 2 L (100 g of IgG) or 6L (300 g of IgG) of colostrum replacer (CR) to obtain either failure (F) or successful (S) transfer of passive immunity, respectively. Upon arrival at the facility, serum IgG concentrations were measured; therefore, F and S calves were identified accordingly and randomly assigned to one of two milk replacer (MR) feeding schemes: Moderate (Mod; ~8 L) or Low (Low; ~4 L). In total, there were 4 treatments resulting from the 2 × 2 factorial design: F-Mod, F-Low, S-Mod, S-Low (n = 30/treatment). Calves were individually housed and fed twice daily until d 42, gradually weaned until d 56, and had free access to straw and water during the study. On d 22, a calf pelleted starter was offered. To evaluate organ and gastroinstetinal tract development, 10 calves/treatment were euthanized at 84 d of age. Other measurements include weekly BW, daily intakes, and daily fecal score until d 21. Data were analyzed by PROC MIXED in SAS accounting for the fixed effects of block, CR, MR, and time, and their interaction. Time entered the model as a repeated statement, and initial BW was used as a covariable when appropriate. Initial BW was not different across treatments, whereas serum IgG was greater in S calves (S = 1,962.9 vs. F = 941.0 mg IgG/dL). During the study, BW was influenced by both CR (P = 0.001) and MR (P < 0.001), where S and Mod calves consistently exhibited greater BW when compared with F and Low calves, respectively. At d 84, Mod calves (F-Mod and S-Mod) were on average 18 kg heavier than Low calves. Similarly, Mod calves exhibited greater fresh tissue weights in the liver, pancreas, spleen, and both the small and large intestines (P < 0.05). Starter intake was influenced by MR (P < 0.001), with Low calves having the greatest intake before and during weaning. However, post-weaning starter intake was greater (P = 0.010) in Mod calves. Fecal consistency was influenced by CR (P = 0.001) and MR (P < 0.001), with S and Low calves having improved fecal consistency. Although no interactions were observed between CR and MR, these findings underscore the importance of considering both colostrum and MR levels in calf nutrition management to optimize growth and improve animal welfare during the early stages of life.

The objective of this study was to evaluate the digestive tract recovery and metabolism of feeding either bovine colostrum (BC), transition milk (TM), or milk replacer (MR) after an episode of feed restriction and fasting (FRF) in dairy calves. Thirty-five Holstein male calves (22 ± 4.8 d old) were involved in a 50-d study. After 3 d of feeding 2 L of rehydration solution twice daily and 19 h of fasting (d 1 of study), calves were randomly assigned to one of the 5 feeding treatments (n = 7): calves were offered either pooled BC during 4 (C4) or 10 (C10) days, pooled TM during 4 (TM4) or 10 (TM10) days, or MR for 10 d (CTRL) at the rate of 720 g/d DM content. Then, all calves were fed the same feeding program, gradually decreasing MR from 3 L twice daily to 2 L once daily at 12.5% DM until weaning (d 42), and concentrate feed, water, and straw were offered ad libitum until d 50. Citrulline, Cr-EDTA, β-hydroxybutyrate (BHB), and nonesterified fatty acids (NEFA) in serum and complete blood count (CBC) were determined on d -3, 1, 2, 5, and 11 relative to FRF, except BHB and NEFA at d -3. Volatile fatty acids (VFA), lactoferrin (LTF), IgA, and microbiota (Firmicutes to Bacteroidetes ratio and Fecalis prausnitzii) were analyzed in feces on d 5 and 11 before the morning feeding. Health scores were recorded daily from d -3 to d 14 as well as d 23 and 30. Feed concentrate, MR, and straw intake were recorded daily, and body weight on d -3, 1, 2, 5, and 11 and weekly afterward. Calf performance, intake, serum Cr-EDTA, CBC, fecal LTF concentrations and microbiota parameters were similar among treatments throughout the study. Serum NEFA concentrations were greater in TM4, TM10 and C10 calves compared with the CTRL ones from d 2 to 11, and after the FRF, serum concentrations of BHB were lower in CTRL calves than in the other treatments, and on d 11, serum BHB concentrations in the long treatments (C10 and TM10) remained greater than those in the shorter ones (C4 and TM4) and CTRL. Serum citrulline concentrations were similar on d -3 and 1 in all treatments, but they were greater in C4, C10, TM4, and TM10 on d 2 and 5, and on d 11 they were only greater in C10 and TM10 than in CTRL calves. Fecal IgA concentrations tended to be greater in C10 than in CTRL, TM4, and TM10 calves, and in C4 and TM10 than in CTRL animals. Fecal propionate proportion was lesser in C10 than in CTRL, TM4, and TM10 calves, while butyrate was greater in C4 and C10 than in TM4 and CTRL calves. The proportion of non-normal fecal scores of C10 fed calves was greater than TM4 and TM10 calves. Results showed that TM and BC may help to recover intestinal functionality, provide gut immune protection, and increase liver fatty acid oxidation in calves after a FRF episode.

The gastrointestinal tract of unweaned calves is compromised after the stress and feed restriction due to marketing and transportation. The use of feed additives to enhance intake and gut immunity at farm arrival could be a strategy to minimize those negative effects. A total of 70 dairy beef calves (50.9 ± 1.66 kg) coming from auction market and with a compromised gut integrity at arrival were used to evaluate the effect of various feed additives [FA; comprising palatability enhancers (PE), standardized olive pomace extract (OE), and tributyrin (TB)] on performance until 2 weeks after weaning. Calves were distributed in 5 treatments: calves fed milk replacer (MR) and concentrate without FA (CTR; n = 14); calves fed MR and concentrate with PE (PE; n = 14); calves fed MR with OE + PE and concentrate with PE (OEPE; n = 14), calves fed MR with TB + PE and concentrate with PE (TBPE; n = 14); and calves fed MR with OE + TB + PE and concentrate with PE (complete - COM; n = 14). At arrival animals received 2.5 L of MR twice daily at 12.5% and ad libitum concentrate feed. On day 35 of the study, animals were submitted to a social stress challenge, calves within one treatment were mixed for 24 h, and on day 36, calves returned to their home pens and the afternoon milk was removed. On day 42, all calves were weaned, and they were followed until day 56. Data were analyzed with a mixed-effects model. After transportation calves had an average of 1.6 ± 0.09 mg/L of serum Cr-EDTA the first week after arrival indicating that those calves had increased gastrointestinal permeability and a compromised gut barrier for a full week; consequently, concentrate intake during that week was decreased for all treatments (P = 0.56) with an average of 27 g·calf-1·d-1. An interaction between treatment and time (P < 0.01) was observed on concentrate intake the last two weeks of the study when calves were already weaned; on week 7, from day 42 to d 49, COM and TBPE calves had greater concentrate intake than CTR calves, and PE and OEPE did not differ among others; and on week 8, between day 42 and day 49, COM calves had the greater concentrate intake than CTR, while other treatments were in between. Although only numerical differences were observed in final BW, COM calves were heavier than the rest of the treatments at the end of the study. In calves with severe problems of gastrointestinal permeability at arrival, the mixture of palatability enhancers, standardized olive pomace extract, and tributyrin increases concentrate intake and potentially improve the recovery of the animals.

The aim of this study was to evaluate the effects of colostrum consumption and feed restriction on biomarkers of stress, nutritional and health status, gut functionality, and behavior in male dairy beef calves being marketed and transported. A total of 82 male Holstein calves (42 ± 1.2 kg of body weight and 14 ± 0.9 d of age) were used to study the amount of colostrum given at birth at the dairy farm of origin, the degree of feed restriction suffered at an assembly center simulation (d -4 to d -1), and the effects of a 19 h transportation (d -1). Treatments were as follows: control calves (CTRL; n = 16) were fed 10 L of colostrum at the dairy farm of origin, milk replacer (MR) and concentrate at the assembly center, and were not transported; calves fed high colostrum and milk replacer (HCMR; n = 17) were given 10 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; calved fed high colostrum and rehydrating solution (HCRS; n = 16) were given 10 L of colostrum at the dairy farm of origin, a rehydrating solution (RS) at the assembly center, and transported; calves fed low colostrum and milk replacer (LCMR; n = 17) were given 2 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; and calves fed low colostrum and rehydrating solution (LCRS; n = 16) were given 2 L of colostrum at the dairy farm of origin, RS at the assembly center, and transported. Transported calves mimic a 19-h transportation. After transport, all calves were fed 2.5 L of MR twice daily and had ad libitum access to concentrate, straw, and water. Calves' recovery was followed for 7 d. Concentrate intake and health records were collected daily from d -4 until d 7 and body weight (BW) and blood samples were collected on d -4, -1, 0, 1, 2, and 7 of the study. Results showed that the feeding regimen provided at the assembly center reduced BW for the HCRS and LCRS calves compared with the CTRL, HCMR, and LCMR calves. Concentrate intake peaked on d 0 in the transported calves, followed by a reduction of intake on d 1 after transportation. Concentrate intake recovery was lower for the LCRS and LCMR calves. On d -1, nonesterified fatty acids and β-hydroxybutyrate concentrations were greater for the HCRS and LCRS calves compared with the CTRL, HCMR, and HCRS calves. After transportation, serum Cr-EDTA concentration was greater for the HCRS and LCRS calves than the HCMR, LCMR, and CTRL calves. The LCRS calves had the lowest serum concentration of citrulline. Finally, health scores were greater for the LCRS calves from d 0 to 7. In summary, both the greatest degree of feed restriction during the assembly center and the low colostrum consumption at birth negatively affected the recovery of concentrate consumption and BW, gut functionality, health status, and behavior in calves after arrival at the rearing farm.