Energy requirement for primiparous Holstein × Gyr crossbred dairy cows.

Our objective was to estimate the requirements of metabolizable energy (ME) and net energy for the maintenance (NEm) of lactating and dry cows, the efficiency of ME utilization for milk production (kl) and tissue gain (kg), and the use of body energy mobilization for milk production (kt) throughout the lactation of primiparous crossbred Holstein × Gyr cows, using open-circuit respiration chambers. Twenty-nine primiparous Holstein × Gyr crossbred cows with an initial BW averaging 563 ± 40.1 kg and 2.5 ± 0.09 years old were used throughout lactation and dry periods. The cows were kept non-pregnant throughout the study to eliminate possible confounding factors. Apparent digestibility assays, followed by calorimeter measurements, were performed 6 times throughout the lactation period. In the dry-off period, the cows were also evaluated but fed with restricted intake (DMI = 1.1% BW/d) to achieve heat production close to maintenance. After 21 d of diet adaptation, an apparent digestibility assay followed by calorimeter measurements was performed. Parameter estimates for lactation period were obtained by mixed models including lactation stage as repeated measures. For restricted feeding at dry-off and fasting period assays, the requirements were estimated by exponential regression. For whole lactation, the values of MEm and NEm were 0.588 and 0.395 MJ/BW0.75, respectively. The efficiencies klkgkt were 0.672, 0.771, and 0.814, respectively. However, MEm and NEm were higher in early and mid-lactation than late, while kl was higher in early than other lactation stages. Dry and non-pregnant cows had MEm of 0.434 MJ/BW0.75 and NEm of 0.351 MJ/BW0.75 for maintenance level, and MEm of 0.396 MJ/BW0.75 and NEm of 0.345 MJ/BW0.75 for fasting metabolism level and efficiency of ME utilization for maintenance was 0.80. Our findings confirmed that F1 crossbred Holstein × Gyr dairy cows have differences in energy requirement and efficiency throughout the lactation stages, suggesting the use of different values in each stage. The estimated values of energy requirement for maintenance and efficiencies for primiparous lactating crossbred Holstein × Gyr were similar to those reported in the literature in specific studies and requirements systems.

Association of passive immunity and genetic composition, health, and performance of tropical dairy calves.

This retrospective cohort study aimed to identify risk factors for the failure of transfer of passive immunity (FPI) in preweaned dairy calves, explore its associations with morbidity, mortality, genetics, and determine a standardized cut-off point for FPI. Analyzing data from 6011 calves, factors such as sire predicted transmitted ability for milk (PTA), birth season, retained placenta (RP), total serum protein concentration (TSP), morbidity (neonatal calf diarrhea - NCD, bovine respiratory disease - BRD, tick-borne disease - TBD), mortality, and average daily weight gain (ADG) were considered. The calves were categorized into predominantly Gyr (PG) and predominantly Holstein (PH) genetic composition groups. Multivariate mixed logistic regression revealed optimal TSP cut-off points for predicting morbidity (7.6 g/dL) and mortality (6.9 g/dL). PH calves exhibited 1.35 times higher odds of FPI and 1.48 times greater odds of disease. Calves from multiparous cows and those born to dams with RP had increased FPI odds. Disease prevalence was 53%, with 41% NCD, 18% BRD, and 10% TBD. Season, parity, PTA, and birth weight were associated with disease odds, though FPI was not a reliable predictor. The mortality percentage was 6%, with PH calves and those with a positive PTA having higher odds. The ADG was 0.64 kg, and FPI-affected calves gained less weight. The study compared and identified various risk factors that potentially impact calf immunity. However, the use of a standardized cut-off point for FPI assessment was not effective in predicting morbidity and mortality at this specific farm.

Invited review: Total solids concentration in milk or milk replacer for dairy calves.

Restricting milk or milk replacer (MR) fed to dairy calves to 10% of body weight at 12.5% total solids (TS) concentration is a common feeding strategy that promotes early weaning and lowers total feed costs for raising young calves. However, this strategy has been associated with inferior performance and compromised welfare. Because a restricted liquid nutrition plan limits calf growth due to limited supply of nutrients, research on increased supply of nutrients from liquid has shown improved growth, health, and welfare of calves. Nutrient supply may be increased by feeding larger amounts of milk or MR averaging 12.5% TS, or by increasing TS above the usual 12.5% TS by increasing MR TS concentration alone (TS+), or by increasing TS concentration and volume simultaneously (TSV+). The objective of this review is to discuss liquid nutrition plans with greater TS concentration in MR or in milk diets, considering the effects of such strategies on performance and digestive tract development before weaning and the future performance of dairy calves. This review will focus on liquid nutrition plans that are based on increased TS concentration (i.e., TS+ or TSV+); therefore, enhanced liquid nutrition plans based only on increased volumes will not be the discussed. Improved growth rates have been observed in calves fed TSV+ programs. However, reduced starter intake preweaning can also have negative effects on dry matter intake, average daily gain, and digestibility postweaning. Feeding a TS+ program may reduce impairment of starter intake and therefore have positive effects on performance, nutrient digestibility, and health. When considering an accelerated nutrition plan with TS+ or TSV+, it is important to consider osmolality of the liquid diet. Further studies are necessary to confirm this hypothesis and the cost-benefit of alternative liquid nutrition plans, as well as the optimal TS concentration of milk or MR fed to dairy calves.

Using rumination and activity data for early detection of anaplasmosis disease in dairy heifer calves.

Bovine anaplasmosis causes considerable economic losses in dairy cattle production systems worldwide, ranging from $300 million to $900 million annually. It is commonly detected through rectal temperature, blood smear microscopy, and packed cell volume (PCV). Such methodologies are laborious, costly, and difficult to systematically implement in large-scale operations. The objectives of this study were to evaluate (1) rumination and activity data collected by Hr-Tag sensors (SCR Engineers Ltd.) in heifer calves exposed to anaplasmosis; and (2) the predictive ability of recurrent neural networks in early identification of anaplasmosis. Additionally, we aimed to investigate the effect of time series length before disease diagnosis (5, 7, 10, or 12 consecutive days) on the predictive performance of recurrent neural networks, and how early anaplasmosis disease can be detected in dairy calves (5, 3, and 1 d in advance). Twenty-three heifer calves aged 119 ± 15 (mean ± SD) d and weighing 148 ± 20 kg of body weight were challenged with 2 × 107 erythrocytes infected with UFMG1 strain (GenBank no. EU676176) isolated from Anaplasma marginale. After inoculation, animals were monitored daily by assessing PCV. The lowest PCV value (14 ± 1.8%) and the finding of rickettsia on blood smears were used as a criterion to classify an animal as sick (d 0). Rumination and activity data were collected continuously and automatically at 2-h intervals, using SCR Heatime Hr-Tag collars. Two time series were built including last sequence of -5, -7, -10, or -12 d preceding d 0 or a sequence of 5, 7, 10, or 12 d randomly selected in a window from -50 to -15 d before d 0 to ensure a sequence of days in which PCV was considered normal (32 ± 2.4%). Long short-term memory was used as a predictive approach, and a leave-one-animal-out cross-validation (LOAOCV) was used to assess prediction quality. Anaplasmosis disease reduced 34 and 11% of rumination and activity, respectively. The accuracy, sensitivity, and specificity of long short-term memory in detecting anaplasmosis ranged from 87 to 98%, 83 to 100%, and 83 to 100%, respectively, using rumination data. For activity data, the accuracy, sensitivity, and specificity varied from 70 to 98%, 61 to 100%, and 74 to 100%, respectively. Predictive performance did not improve when combining rumination and activity. The use of longer time-series did not improve the performance of models to predict anaplasmosis. The accuracy and sensitivity in predicting anaplasmosis up to 3 d before clinical diagnosis (d 0) were greater than 80%, confirming the possibility for early identification of anaplasmosis disease. These findings indicate the great potential of wearable sensors in early identification of anaplasmosis diseases. This could positively affect the profitability of dairy farmers and animal welfare.

Relationship between feed efficiency indexes and thermography, blood, and ruminal parameters in pre-weaning dairy heifers.

The objective of this study was to evaluate whether pre-weaning heifer calves divergent for residual feed intake (RFI) or residual feed intake and body weight gain (RIG) exhibit differences in thermography, blood, and ruminal parameters. Thirty-two Gyr heifer calves were enrolled in a 63-d trial and classified into 2 feed efficiency (FE) groups based on RFI and RIG (mean ± 0.5 SD). The groups were classified as high efficiency (HE) RFI (HE RFI, n = 9), HE RIG (HE RIG, n = 10), low efficiency (LE) RFI (LE RFI, n = 10), and LE RIG (LE RIG, n = 11). The amount of whole milk provided for each calf was calculated based on their metabolic weight at birth (42% x BW0.75). The liquid diet was divided into two meals at 0700 and 1400 h. The total solid diet (TSD) was composed of 92% concentrate and 8% of Tifton 85 hay chopped in 5-cm lengths, as fed. Intake was measured daily. Blood concentrations of insulin, beta hydroxybutyrate, urea, and glucose, and ruminal pH, N-NH3, and volatile fatty acids (VFA) were evaluated at 14, 28, 42, 56, and 70 days of age. Thermal images of the calves were taken with an infrared camera (FLIR T420, FLIR Systems Inc., Wilsonville, OR) on d 56 (±3) at 0600 h, before the morning feeding. Total VFA concentration and propionate as % of total VFA were 24.2% and 22.2% lower in HE RFI compared to LE RFI calves, respectively. On the other hand, acetate as % of total VFA was 10.6% greater in HE RFI than LE RFI calves. Blood urea concentration tended to be greater in LE RFI than HE RFI calves. High efficiency HE RIG tended to have 6.8% greater acetate and 15.4% lower propionate as % of total VFA than LE RIG. Blood insulin concentration was greater and blood glucose tended to be greater for LE RIG than HE RIG group. Low efficiency RIG group had greater left rib, left flank, and anus surface temperature measured by infrared thermography than the HE RIG group. Differences in ruminal fermentation do not seem to be associated with pre-weaning calves efficiency, while differences in protein metabolism seem to affect RFI during this phase. Infrared thermography appears to be correlated to RIG in pre-weaning heifer calves.

Supplementation with different non-fiber carbohydrate sources in dairy cow diets with high or low rumen-undegradable protein content / Suplementação com diferentes fontes de carboidratos não fibrosos em dietas para vacas leiteiras com alto ou baixo teor de proteína não degradável no rúmen

The objective for this study was to evaluate the supplementation with different non-fibrous carbohydrate (NFC) sources for grazing dairy cows in diets with high or low concentrations of rumen undegradable protein (RUP). Twelve multiparous cows averaging 30kg/d of milk production and 45±23 days in milk in a 4x4 Latin square design with 2 × 2 factorial arrangement were used. The difference in NFC content of the diets was achieved using ground corn (GC) or dried citrus pulp (DCP). Dietary RUP was altered by the partial replacement of soybean meal (LRUP) by roasted whole soybean and corn gluten meal (HRUP). Greater dry matter intake (DMI) was observed in DCP treatments compared to GC treatments (19.2 and 17.7kg/day of DM, respectively). Milk fat concentration was lower for LRUP treatments (3.4%) when compared to HRUP (3.6%). The milk protein concentration was greater for GC treatments (2.9%) in relation to DCP treatments (2.8%). Lower milk ureic nitrogen was observed when DCP diets were fed compared to those with GC (17.8 and 21.2mg/dL, respectively). The use of DCP as CNF source increased dry matter intake as well as milk fat concentration, although no differences in milk production were observed for RUP level.(AU)

Objetivou-se avaliar a suplementação com diferentes fontes de carboidratos não fibrosos (CNF) em vacas manejadas a pasto em dietas com alta ou baixa concentração de proteína não degradável no rúmen (PNDR). Doze vacas multíparas com média de 30kg leite/ dia e 45±23 dias em lactação foram utilizadas em delineamento quadrado latino 4x4 com arranjo fatorial 2 × 2. As fontes de CNF foram milho moído (MM) e polpa cítrica seca (PC). A PNDR da dieta foi alterada pela substituição parcial do farelo de soja da dieta de baixa PNDR (BPNDR) por grão de soja tostado e farelo de glúten de milho dieta de alta PNDR (APNDR). Foi observado maior consumo de matéria seca (CMS) nos tratamentos com PC quando comparado aos tratamentos com MM (19,2 e 17,7kg / dia de MS, respectivamente). O teor de gordura do leite foi menor para os tratamentos com BPNDR (3,4%) em comparação aos tratamentos com APNDR (3,6%). O teor de proteína do leite foi maior nos tratamentos com MM (2,9%) em relação aos tratamentos com PC (2,8%). Foram observados menores teores de nitrogênio ureico no leite dos animais alimentados com PC em relação aos com MM (17,8 e 21,2mg / dL, respectivamente). O uso de PC como fonte de CNF aumentou o consumo de matéria seca, bem como o teor de gordura do leite, embora não tenham sido observadas diferenças na produção de leite relacionada a alteração nos teores de PNDR.(AU)

Short communication: Tick-borne disease is associated with changes in feeding behavior in automatically fed weaned dairy calves.

Tick-borne disease is a hemolytic disease complex that causes extensive losses to the dairy industry in tropical regions. Its timely diagnosis is challenging and labor intensive. Our objective was to investigate whether tick-borne disease was associated with changes in ingestive behavior of weaned dairy calves. Weaned calves (n = 35) enrolled at 108 ± 8 d of age were group housed (n = 12, 12, and 11/group) for 4 wk in the experimental pen, which had 12 electronic feed bins and 2 electronic water bins. Data were automatically collected at each feed or water bin visit via radio frequency identification ear tags. Water and total mixed ration were provided ad libitum. Calves were examined weekly for tick-borne disease detection. A disease bout was confirmed if packed cell volume was ≤25% at any exam. Diseased calves received antimicrobial and antipyretic treatment. Data were summarized by day within bin type (feed or water) as intake (kg/d; as-fed basis), frequency of visits (visits/d), and total duration of visits (min/d). Day of detection was set as d 0; a 9-d behavioral screening period for evaluation of behavioral changes was set according to d 0 (d -4 to +4). A within-calf mean was calculated for the healthy period (HP; mean of all days between 2 consecutive negative exams) for each response variable. Data were analyzed as within-calf differences between HP and each day of the behavioral screening period. Tick-borne disease was detected in 12 calves; thus, only data referent to these animals were included in the analyses. Compared with HP, daily feed intake was reduced on d -1, 0, and +1, and daily frequency and total duration of feed bin visits were reduced from d -3 to d +4. Daily feed intake was reduced by 35% on d -1 (3.5 ± 0.4 vs. 5.4 ± 0.5 kg/d for HP), and daily frequency and duration of visits were reduced by 27% (56.3 ± 7.8 vs. 76.7 ± 8.1 visits/d for HP) and 24% (27.0 ± 3.8 vs. 35.4 ± 3.9 min/d for HP) on d -3, respectively. Daily water intake on d 0 (9.1 ± 1.4 kg/d) was lower than at HP (12.9 ± 1.6 kg/d), but other drinking behaviors were not different from healthy means during the screening period. Feeding behavior, but not drinking behavior, was different from HP means before detection at weekly exams. Therefore, feeding behavior could be further explored for the development of algorithms for tick-borne disease detection.

Phenotypically divergent classification of preweaned heifer calves for feed efficiency indexes and their correlations with heat production and thermography.

The aims of this study were (1) to assess if there is phenotypical divergence for feed efficiency (FE) during the preweaning phase; (2) if FE is correlated with heat production (HP) measured by the face mask method or (3) by surface skin temperature via thermography, and (4) whether these methods are applicable to preweaned calves. Holstein × Gyr heifer calves (n = 36, birth body weight = 32.4 ± 6.6 kg) were enrolled and on trial between 4 and 12 wk of age and were classified into 2 residual feed intake (RFI) and residual body weight gain (RG) groups: high efficiency (HE; RFI, n = 10; and RG, n = 9) and low efficiency (LE; RFI, n = 10; and RG, n = 8). Calves were fed milk (6 L/d) and solid feed (95% starter and 5% chopped Tifton 85 hay, as fed). Growth was monitored weekly and feed intake (milk and solid feed) daily, during the whole period. Gas exchanges (O2 consumption and production of CO2 and CH4) were obtained using a face mask at 45 ± 5 d of age and HP was estimated. Maximum temperatures were measured at 7 sites with an infrared camera at 62 ± 7 d of age. There was divergence in RFI and RG. Respectively, HE and LE calves had RFI of -0.14 and 0.13 kg/d, and RG of 0.05 and -0.07 kg/d. Dry matter intake was 15% lower in HE-RFI compared with LE-RFI, but no differences were observed in average daily weight gain. Within the RG test, no differences were observed in dry matter intake or average daily gain. The HE-RFI calves consumed less O2 (L/d) and produced less CO2 (L/d). Heart rate and HP were lower for HE-RFI calves compared with LE-RFI. Residual feed intake was correlated with HP (r = 0.48), O2 consumption (r = 0.48), CO2 production (r = 0.48), and heart rate (r = 0.40). No differences were observed in HP and gas exchanges between RG groups. Methane production was null in both groups. Eye temperature measured by thermography was 0.5°C greater in HE-RG than LE-RG calves. Differences in skin temperature between HE and LE calves were not observed at the other sites. These results support the hypothesis that calves are divergent for RFI, RG, and FE during preweaning and divergence tests are applicable during this phase. The face mask method described here is a useful tool for estimating differences in HP among phenotypically divergent RFI calves. Eye temperature measured by infrared thermography may have potential to screen phenotypically divergent RG calves.

The effects of increasing amounts of milk replacer powder added to whole milk on mammary gland measurements using ultrasound in dairy heifers.

The aim of this study was to determine the effect of increasing total solids (TS) in the liquid diet during the preweaning phase on mammary gland development in dairy heifers. The increase in TS was obtained with the addition of milk replacer powder to whole milk. Crossbreed Holstein-Gyr heifers (n = 60) were distributed in 4 treatments with different TS concentrations: 13.5% (n = 15), 16.1% (n = 15), 18.2% (n = 15), and 20.4% (n = 15). The liquid diets were provided from 5 to 55 d of age. From 56 to 59 d of age, the total amount of liquid feed was reduced by half. Heifers were weaned at 60 d and monitored until 90 d of age. Ultrasound mammary gland evaluations were performed weekly between 5 to 11 wk of age, using a B-mode ultrasound equipped with microconvex transducer at a frequency of 6 MHz. In those same weeks, the manual palpation of mammary parenchyma (PAR) was performed. Increased TS concentration of liquid diet during the preweaning period increased body weight of heifers, but did not alter PAR growth and the deposition of adipose tissue in the mammary gland evaluated by ultrasonography. The oval-shaped structure of PAR was altered after 2 mo of age. In the evaluated period, PAR growth was isometric with respect to the body growth rate. Palpation scoring of PAR had a strong correlation with the ultrasound evaluation of the PAR.

Validation of a system for monitoring individual feeding and drinking behaviour and intake in young cattle.

The objective of this study was to validate an electronic system for monitoring individual feeding and drinking behaviour and intake developed for young cattle housed in group. A total of 35 Holstein-Gyr crossbred heifers (BW: 180±52 kg; age: 121.5±32.5 days), fitted with an ear tag containing a unique passive transponder, were distributed in three groups of 12, 12 and 11 animals per period and had free access to 12 electronic feed bins and two electronic water bins (Intergado® Ltd). The dimensions of feed and water bins, as well as the sensors position were appropriate for young cattle. The system documented the visit frequency and duration, as well as the feed and water intakes, by recording the animal's identification tag, bin number, initial and final times of visits and the difference of feed/water weight at the start and end of each bin visit. Feed bins were monitored using time-lapse video recording over 4 days and the water bins were monitored over 6 days. For each feed bin, two feeding events were monitored using manual weighings with an external scale immediately before and after the animal's visit and the difference between them was assumed as feed intake (n=24 observations). For the water bins, 60 manual weighings were made. Video and manual weighing data were regressed on the electronic feeding and drinking behaviour and intake data to evaluate the system's precision and accuracy. The system showed high specificity (98.98% and 98.56% for the feed and water bins, respectively) and sensitivity (99.25% and 98.74%, respectively) for identifying an animal's presence or absence. Duration of feed and water bin visits as well as feed and water consumption per visit estimated by the system were highly correlated and precise compared with the observed video and manual weighing data (r 2=0.917, 0.963, 0.973 and 0.986, respectively). It was concluded that Intergado® system is a useful tool for monitoring feeding and drinking behaviour as well as water and feed intakes in young cattle housed in groups.

Effect of increasing amounts of milk replacer powder added to whole milk on postweaning performance, reproduction, glucose metabolism, and mammary fat pad in dairy heifers.

The aim of this study was to evaluate the effects of increasing the total solids (TS) content of liquid feed, by adding increasing amounts of milk replacer powder to whole milk, on age at puberty and postweaning performance, glucose metabolism, and mammary fat pad of dairy heifers. Crossbreed Holstein × Gyr heifers (n = 58) were distributed into 4 different treatments during the preweaning period. Treatments consisted of liquid feeds with TS content of 12.5 (actual TS = 13.5 ± 0.53%; n = 15), 15.0 (actual TS = 16.1 ± 0.03%; n = 15), 17.5 (actual TS = 18.2 ± 0.14%; n = 13), or 20.0% (actual TS = 20.4 ± 0.24%; n = 15), which were provided up to 59 d old. From 60 to 89 d old, the animals received the same starter offered during the preweaning period in addition to corn silage ad libitum starting at 70 d old. From 90 to 104 d old, the animals were adapted to a total mixed ration. At 105 d old, the animals were distributed in 4 paddocks equipped with electronic feed and water bins and were fed the same total mixed ration ad libitum. A period of adaptation to the electronic feed bins occurred from 105 to 119 d old. Feed and water intake and body weight and body frame development were assessed until puberty. Mammary gland evaluations were performed monthly by ultrasonography from 120 d of age until puberty onset. Puberty onset was determined as plasma progesterone concentration greater than 1 ng/mL in 2 consecutive samples collected 7 d apart. The date of puberty onset was recorded as the collection day of the first of these samples. A glucose tolerance test was performed at 280 d of age. The increased TS content of the liquid feed fed during the preweaning period did not affect dry matter intake, performance, age at puberty, glucose metabolism, or mammary gland fat pad at later stages of rearing process. Conversely, hip width and heart girth increased linearly up to 150 and 240 d of age, respectively, as a result of the increased TS concentration of the liquid feed during the preweaning period.

The effects of increasing amounts of milk replacer powder added to whole milk on passage rate, nutrient digestibility, ruminal development, and body composition in dairy calves.

The aim of this study was to evaluate the effects on feed intake, calf performance, feed efficiency, fecal score, passage rate, apparent nutrient digestibility, development of rumen and other organs, and body composition of increasing the total solids content of liquid feed (whole milk) by adding increasing amounts of milk replacer powder during the preweaning period. Crossbred Holstein-Gyr calves (n=32) were assigned to 1 of 4 treatments (n=8 per group), which consisted of different total solids concentrations: 12.5, 15.0, 17.5, and 20.0% of liquid feed. Calves received 6 L of liquid per day, divided into 2 equal meals (0800 and 1600 h) and provided in buckets, from 5 to 55d of age. Starter and water were provided ad libitum during the entire experiment. At 56d of age, animals were killed. Laboratory analysis determined that the actual total solids contents of the liquid feed were 13.5, 16.1, 18.2, and 20.4%, for the proposed 12.5, 15.0, 17.5, and 20.0% total solids treatments, respectively. The osmolality of liquid feed treatments was 265 to 533 mOsm/L. Fecal score was similar among treatments, except for wk 2 and 7. Intake of liquid feed was similar among treatments from 6wk of age. During wk 4, 5, and 6, we detected a linear decrease in starter intake. After wk 7, we observed greater starter intake for calves fed approximately 16.1% total solids. Water intake, feed efficiency, and withers height were similar among treatments. Increasing concentrations of total solids in liquid feed quadratically affected average daily gain, final body weight, and empty body weight. We observed a greater average daily gain for calves fed approximately 20.4% total solids. Passage rate, nutrient digestibility, development of pre-stomachs and intestine, and body composition were similar among treatments. Increasing the concentration of total solids in liquid feed up to 20.4% reduced starter intake between 4 and 6wk of life, but increased average daily gain. It did not affect passage rate, nutrient digestibility, ruminal and organ development, or body composition in calves during the preweaning period, indicating that this strategy may be a viable alternative for feeding without increasing the total volume of liquid feed provided to dairy calves.

The effects of increasing amounts of milk replacer powder added to whole milk on feed intake and performance in dairy heifers.

The aim of this study was to evaluate the effects on feed intake, heifer performance, and health of increasing the total solids (TS) content of liquid feed (whole milk) by adding increasing amounts of milk replacer powder during the pre- and postweaning periods. Crossbred Holstein-Gyr heifers (n=60) were assigned to 1 of 4 treatments (n=15 per group), which consisted of different TS concentrations: 12.5, 15.0, 17.5, and 20.0% of liquid feed. Heifers received 6 L of liquid feed per day, divided into 2 equal meals (0800 and 1600h) and provided in buckets, from 5 to 55d of age. From 56 to 59d of age, the total amount of liquid feed was reduced by half, maintaining only morning feedings. Heifers were weaned at 60d and monitored until 90d of age. Water and starter were provided ad libitum during the entire experiment. Corn silage was included in the diet during the postweaning period (70d of age). Feed intake and health scores were evaluated daily. Body weight and body frame development were recorded weekly. Starting at 14d, ruminal pH was measured every other week. Laboratory analysis determined that the actual TS contents of the liquid feed were 13.5, 16.1, 18.2, and 20.4%, for the proposed 12.5, 15.0, 17.5, and 20.0% TS treatments, respectively. The osmolality of liquid feed treatments was 265 to 533mOsm/L. Intake of liquid feed was similar among treatments from 4wk of age. During the preweaning period, starter intake, fecal score, and days with diarrhea were similar among treatments. Ruminal pH at weaning averaged 6.2 and was similar among treatments. Increasing concentrations of TS in the liquid feed were associated with linear increases in average daily gain, final body weight, and growth performance, but linear decreases in feed efficiency. During the postweaning period, intake of starter, corn silage, and water were similar among treatments, as well as average daily gain and feed efficiency. Final body weight and growth performance during the postweaning period also increased linearly with concentration of TS in liquid feed. Increasing the concentration of TS in liquid feed up to 20.4% increased performance and body frame development in dairy heifers during the pre- and postweaning periods and had no effects on solid feed intake or health.

Effects of bovine mammary gland biopsy and increased milking frequency on post-procedure udder health, histology, and milk yield.

Sixteen cows in early lactation were randomly distributed into two groups in order to evaluate the effects of mammary biopsies and increased milking frequency on tissue characteristics, post-biopsy udder health and histology. One group was milked twice a day (2×) starting on the 2nd day after calving, until 28 days in milk (DIM). The other group was milked four times a day (4×) from two to 21 DIM, and twice a day (2×) from 22 to 28 DIM. On days 2, 7, 14, 21, and 28 postpartum, one fragment of secretory tissue was collected from one mammary quarter at a time. Collections were alternated between the four mammary quarters per collection day. A total of 80 mammary tissue samples were collected. Qualitative and quantitative analyses of the tissues were conducted by histologic examination. Animal health was assessed by observation of feed intake behavior immediately after biopsy, and weight and body condition score before and one week after biopsy. Udder health was assessed daily from calving to 60 DIM with California Mastitis Test (CMT) and by noting alterations in the milk such as blood, milk clots, blood clots, clinical signs of mastitis. Milk composition and somatic cell count (SCC) were analyzed before and after the biopsies. Milk production was evaluated before biopsy, on the day of biopsy, and after the biopsy. An average of 10 fields at 40× magnification was obtained from each sample. There were no evident changes in mammary morphology as a result of milking two or four times/day at any of the evaluated time points. Biopsy wounds healed rapidly without infection. Intramammary bleeding and CMT alterations were observed in 96% and 75% of the biopsied mammary quarters, respectively. Clinical mastitis was diagnosed in 12% of the biopsied quarters. Different milking frequencies had no effect on the frequency and duration of post-biopsy alterations. Milk production decreased after biopsies done on days 2 for 2× and 4× groups, but it returned to pre-biopsy values within 1 day. Milk composition and SCC were affected transiently. Increased milking frequency did not influence udder health. Post-biopsy recovery was rapid and the procedure proved effective without damaging the cows' health.

Cow-specific risk factors for clinical mastitis in Brazilian dairy cattle.

Information related to mastitis risk factors is useful for the design and implementation of clinical mastitis (CM) control programs. The first objective of our study was to model the risk of CM under Brazilian conditions, using cow-specific risk factors. Our second objective was to explore which risk factors were associated with the occurrence of the most common pathogens involved in Brazilian CM infections. The analyses were based on 65 months of data from 9,789 dairy cows and 12,464 CM cases. Cow-specific risk factors that could easily be measured in standard Brazilian dairy farms were used in the statistical analyses, which included logistic regression and multinomial logistic regression. The first month of lactation, high somatic cell count, rainy season and history of clinical mastitis cases were factors associated with CM for both primiparous and multiparous cows. In addition, parity and breed were also associated risk factors for multiparous cows. Of all CM cases, 54% showed positive bacteriological culturing results from which 57% were classified as environmental pathogens, with a large percentage of coliforms (35%). Coagulase-negative Staphylococcus (16%), Streptococcus uberis (9%), Streptococcus agalactiae (7%) and other Streptococci (9%) were also common pathogens. Among the pathogens analyzed, the association of cow-specific risk factors, such as Zebu breed (OR=5.84, 95%CI 3.77-10.77) and accumulated history of SCC (1.76, 95%CI 1.37-2.27), was different for CM caused by Coagulase-negative Staphylococcus and S. agalactiae in comparison to CM caused by coliforms. Our results suggest that CM control programs in Brazil should specially consider the recent history of clinical mastitis cases and the beginning of the lactations, mainly during the rainy season as important risk factor for mastitis.

Technical note: Validation of a system for monitoring individual feeding behavior and individual feed intake in dairy cattle.

The objective of this study was to validate an electronic system for monitoring individual feeding behavior and feed intake (Intergado Ltd., Contagem, Minas Gerais, Brazil) in freestall-housed dairy cattle. No data have been published that validate either the behavioral measurement or the feed intake of this system. Feeding behavior data were recorded for 12 Holstein cows over 5d using an Intergado system and time-lapse video. The cows were fitted with an ear tag containing a unique passive transponder and provided free access to 12 feed bins. The system documented the visit duration and feed intake by recording the animal identification number, bin number, initial and final times, and the difference between feed weight at start and end of each feed bin visit. These data were exported to Intergado web software and reports were generated. Electronic data on animal behavior were compared with video data collected during the same evaluation period. An external scale was used to manually measure and validate the electronic system's ability to monitor dairy cow feed intake for each feed bin visit. The feed intake was manually measured for 4-h time periods and compared with the sum of the feed intake recorded by the monitoring system for each cow visit during the same time period. Video and manual weight data were regressed on the electronic feeding behavior and feeding intake data to evaluate the precision of the monitoring system. The Intergado system presented high values for specificity (99.9%) and sensitivity (99.6%) for cow detection. The visit duration and feed intake per visit collected using the electronic monitoring system were similar to the video and manual weighing data, respectively. The difference between the feed intake measured manually and the sum of the electronically recorded feed intake was less than 250g (25,635±2,428 and 25,391±2,428g estimated using manual weighing and the electronic system, respectively). In conclusion, the Intergado system is a reasonable tool to monitor feeding behavior and feed intake for freestall-housed dairy cows.

Use of F57 bags by the semi-automatic in vitro technique of gas production / Uso de sacos F57 pela técnica in vitro semi-automática de produção de gases

Os cadinhos filtrantes (porosidade 1) originalmente usados na técnica in vitro semi-automática de produção de gases estabelecida no Laboratório de Produção de Gases da Escola de Veterinária da UFMG podem ocasionar interferências nos estudos de quantificação da degradação de alimentos, principalmente os ricos em amido, devido à obstrução dos poros da placa filtrante pelo material residual após fermentação. Este estudo objetivou avaliar a substituição dos cadinhos filtrantes por sacos F57 (Ankom(r)) visando a realização de experimentos in vitro para descrição da cinética de fermentação e degradação ruminal. Esta substituição causou a redução do peso/volume da amostra incubada e desta forma, interferiu na relação pressão (P) / volume (V) e consequentemente inviabilizou a utilização de equação previamente estabelecida por Mauricio et al. (2003). Desta forma, objetivou-se neste estudo estabelecer equação para estimar o volume de gases produzidos a partir de dados de P e V obtidos pela fermentação de sorgo forrageiro, incluindo partes da planta e planta inteira, incubados em sacos F57 (Ankom(r)). Foram quantificados 474 dados simultâneos de pressão e volume os quais variaram de 0 a 4.670 psi e os de volume entre 0 e 38mL. A equação relacionando P e V obtida foi: V (mL) = 0.747 (s.e. 0.0733) + 7.23 P (s.e. 0.1165) + 0.101 P2 (s.e. 0.0372), (R2 = 0.99). O desenvolvimento desta equação viabilizou a utilização dos sacos F57 (Ankom(r)) pela na técnica in vitro semi-automática de produção de gases e, portanto permitindo a quantificação dos resíduos da fermentação favorecendo a acurácia dos resultados...

Suplementação de lisina e metionina em associação ou não com o óleo de soja na dieta de vacas leiteiras / Supplementation of lysine and methionine in association or not with soybean oil in dairy cow diets

O objetivo do estudo foi avaliar a suplementação de lisina e metionina em associação ou não ao óleo de soja na dieta de vacas leiteiras e seus efeitos sobre a produção e a composição do leite. Doze vacas Holandesas foram distribuídas em quadrado latino 4x4, com as dietas O+LM (dieta acrescida de óleo de soja, lisina e metionina misturados na dieta total), OLM (dieta com o complexo óleo de soja/lisina e metionina fornecido separadamente da dieta total), OS (dieta acrescida de óleo de soja fornecido separadamente da dieta total) e LM (dieta acrescida de lisina e metionina fornecidos separadamente da dieta total). A produção de leite, a de proteína e a de gordura não foram afetadas pela adição de lisina e metionina associadas ou não com óleo de soja. O percentual de gordura do leite, a produção de leite corrigida para 3,5% de gordura e a produção de leite corrigida para sólidos totais reduziram-se com a adição de óleo de soja na dieta. O percentual de proteína aumentou 0,14% (p<0,05) com a adição de óleo na presença de lisina e metionina na dieta. Os resultados sugerem efeito protetor do complexo óleo/lisina e metionina da degradação ruminal na condição experimental proposta...

The aim of this study was to evaluate the effects of lysine and methionine supplementation with or without soybean oil in the diet of dairy cows on milk production and composition. Twelve Holstein cows were randomly distributed in a 4x4 latin square where the diets were O+LM (diet with soybean oil, lysine and methionine added in the total mixed ration), OLM (diet with complex soybean oil/ lysine and methionine provided as top dressed), OS (diet with soybean oil provided as top dressed) and LM (diet with lysine and methionine provided as top dressed). The milk production, milk protein and milk fat production were not affected by the addition of lysine and methionine in association or not with soybean oil in the diet. The milk fat percentage, 3.5% fat-corrected milk and solids corrected milk were reduced with increasing soybean oil in the diet. The milk protein percentage increased in 0.14% (P < 0.05) when soybean oil was added to the diet in the presence of the lysine and methionine. The results suggest a protection effect of oil/lysine and methionine complex from the rumen degradation in this experimental condition...

Desenvolvimento de bezerros leiteiros alimentados com silagem de leite de transição: I - Trato digestivo / Development of dairy calves fed silage transition milk: I - Digestive tract

Avaliou-se o desenvolvimento do trato digestivo de bezerros Holandeses aleitados com silagem de leite de transição. Foram utilizados 18 animais, com peso corporal inicial médio de 36,50kg (±4,03), alimentados individualmente em baias com concentrado, feno de Cynodon sp., água e suplemento mineral oferecidos ad libitum. O delineamento experimental foi inteiramente ao acaso, com três tratamentos e seis repetições. Os tratamentos consistiram em leite integral e silagem de leite de transição diluída em água ou misturada em leite, correspondendo a quatro litros diários divididos em duas refeições, durante 59 dias. Aos 60 dias, os bezerros foram abatidos e realizaram-se pesagens do trato digestivo e medidas histológicas das papilas ruminais. O sistema de aleitamento não interferiu nos consumos de concentrado e matéria seca total e no desenvolvimento de papilas ruminais (P>0,05). A silagem de leite de transição diluída em água resultou em menor peso corporal, menor peso corporal vazio e absoluto do abomaso e maior desenvolvimento intestinal. O aleitamento com silagem misturada em leite não comprometeu o desenvolvimento corporal e do trato digestivo até 60 dias de idade, representando alternativa ao aleitamento com leite...

This study aimed to evaluate the development of the digestive tract of Holstein calves which suckled milk from silage transition. We used 18 animals, with an average initial body weight of 36.50kg (±4.03), individually housed in pens with concentrate, hay Cynodon sp., water and mineral supplement offered ad libitum. The experimental design was completely randomized with three treatments and six replications. Treatments consisted of whole milk and silage transitional milk, diluted with water or mixed with milk, corresponding to four liters per day divided over two meals during 59 days. The food intake was monitored daily and weighed every week after the supply of liquid diet in the morning. At 60 days, the calves were slaughtered and the digestive tract was weighed and histological measures of rumen papillae were taken. The nursing system did not affect the consumption of concentrate and total dry matter and the development of rumen papillae (P>0.05). The silage transition milk diluted in water resulted in lower final body weight, lower body weight and absolute emptiness abomasum and intestinal further development. Milk transition silage mixed in milk did not affect the development of the digestive tract and body until 60 days of age, representing an alternative to milk...

Desenvolvimento de bezerros leiteiros alimentados com silagem de leite de transição: II - Órgãos internos / Development of dairy calves fed silage transition milk: II - Internal organs

Avaliou-se o tamanho absoluto e relativo dos órgãos internos de bezerros Holandeses aleitados com leite, silagem de leite de transição diluída em água ou misturada em leite. Foram utilizados 18 animais, machos, com 60 dias de idade e peso corporal médio de 70,3kg (±11,8kg). O delineamento experimental foi inteiramente ao acaso, com três tratamentos e seis repetições. Os animais foram abatidos aos dois meses de idade, sendo previamente submetidos a jejum alimentar de 16 horas. O aleitamento modificou os pesos dos órgãos internos e da gordura omental dos animais, exceto para rins e gordura mesentérica, e não alterou o consumo de alimentos sólidos. A silagem de leite de transição diluída em água comprometeu o desempenho dos bezerros, refletindo no peso dos órgãos internos e de gordura omental, e apresentou pesos absolutos para fígado, baço e gordura omental de 1.072, 186 e 133g, respectivamente. A silagem misturada em leite proporcionou resultados mais semelhantes ao fornecimento exclusivo de leite, demonstrando-se como opção para o aleitamento de bovinos jovens...

This study aimed to evaluate the absolute and relative size of internal organs of Holstein calves which suckled milk, silage transition milk diluted with water or mixed in milk. We used 18 male animals, 60 days old with a mean body weight of 70.3kg (± 11.8kg). The experimental design was completely randomized with three treatments and six replications. The animals were slaughtered at two months, and previously fasted for 16 hours. Breast feeding changed the weights of internal organs and omental fat of animals, except for kidney and mesenteric fat, and did not affect food intake solids. The silage transition milk diluted in water compromised the performance of the calves, reflecting on the weight of internal organs and omental fat, and showed absolute weights for liver, spleen and omental fat of 1072, 186 and 133g, respectively. The silage mixed with milk yielded results more similar to the exclusive milk supply, being an option for suckling calves...