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Accurate estimates of methane (CH4) production by cattle in different contexts are essential to developing mitigation strategies in different regions. We aimed to: (i) compile a database of CH4 emissions from Brazilian cattle studies, (ii) evaluate prediction precision and accuracy of extant proposed equations for cattle and (iii) develop specialized equations for predicting CH4 emissions from cattle in tropical conditions. Data of nutrient intake, diet composition and CH4 emissions were compiled from in vivo studies using open-circuit respiratory chambers, SF6 technique or the GreenFeed® system. A final dataset containing intake, diet composition, digestibility and CH4 emissions (677 individual animal observations, 40 treatment means) obtained from 38 studies conducted in Brazil was used. The dataset was divided into three groups: all animals (GEN), lactating dairy cows (LAC) and growing cattle and non-lactating dairy cows (GCNL). A total of 54 prediction equations available in the literature were evaluated. A total of 96 multiple linear models were developed for predicting CH4 production (MJ/day). The predictor variables were DM intake (DMI), gross energy (GE) intake, BW, DMI as proportion of BW, NDF concentration, ether extract (EE) concentration, dietary proportion of concentrate and GE digestibility. Model selection criteria were significance (P < 0.05) and variance inflation factor lower than three for all predictors. Each model performance was evaluated by leave-one-out cross-validation. The Intergovernmental Panel on Climate Change (2006) Tier 2 method performed better for GEN and GCNL than LAC and overpredicted CH4 production for all datasets. Increasing complexity of the newly developed models resulted in greater performance. The GCNL had a greater number of equations with expanded possibilities to correct for diet characteristics such as EE and NDF concentrations and dietary proportion of concentrate. For the LAC dataset, equations based on intake and animal characteristics were developed. The equations developed in the present study can be useful for accurate and precise estimation of CH4 emissions from cattle in tropical conditions. These equations could improve accuracy of greenhouse gas inventories for tropical countries. The results provide a better understanding of the dietary and animal characteristics that influence the production of enteric CH4 in tropical production systems. [ABSTRACT FROM AUTHOR]

Background and Purpose Spinal voltage-gated calcium channels (VGCCs) are pivotal regulators of painful and inflammatory alterations, representing attractive therapeutic targets. We examined the effects of epidural administration of the P/ Q- and N-type VGCC blockers Tx3-3 and Phα1β, respectively, isolated from the spider P honeutria nigriventer, on symptomatic, inflammatory and functional changes allied to mouse cyclophosphamide ( CPA)-induced haemorrhagic cystitis ( HC). The effects of P . nigriventer-derived toxins were compared with those displayed by MVIIC and MVIIA, extracted from the cone snail Conus magus. Experimental Approach HC was induced by a single i.p. injection of CPA (300 mg·kg-1). Dose- and time-related effects of spinally administered P/Q and N-type VGCC blockers were assessed on nociceptive behaviour and macroscopic inflammation elicited by CPA. The effects of toxins were also evaluated on cell migration, cytokine production, oxidative stress, functional cystometry alterations and TRPV1, TRPA1 and NK1 receptor mRNA expression. Key Results The spinal blockage of P/ Q-type VGCC by Tx3-3 and MVIIC or N-type VGCC by Phα1β attenuated nociceptive and inflammatory events associated with HC, including bladder oxidative stress and cytokine production. CPA produced a slight increase in bladder TRPV1 and TRPA1 mRNA expression, which was reversed by all the toxins tested. Noteworthy, Phα1β strongly prevented bladder neutrophil migration, besides HC-related functional alterations, and its effects were potentiated by co-injecting the selective NK1 receptor antagonist CP-96345. Conclusions and Implications Our results shed new light on the role of spinal P/ Q and N-type VGCC in bladder dysfunctions, pointing out Phα1β as a promising alternative for treating complications associated with CPA-induced HC. [ABSTRACT FROM AUTHOR]

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 55 d of age. Starter and water were provided ad libitum during the entire experiment. At 56 d 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 6 wk 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 6 wk 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate the energy and protein requirements of crossbred (Holstein × Gyr) growing bulls. Twenty-four 10-mo-old bulls [initial body weight (BW) = 184 ± 23.4 kg] were used in a comparative slaughter trial. Six bulls were slaughtered at the beginning of the experiment as the reference group, to estimate initial empty body weight (EBW) and energy and protein contents of the remaining animals. The remaining bulls were assigned to a completely randomized design with 3 levels of dry matter intake and 6 replicates. The levels of dry matter intake were 1.2% of BW, 1.8% of BW, and ad libitum to target orts equal to 5% of the total amount that was fed. The remaining bulls were slaughtered at the end of the experiment. The bulls were fed a diet consisting of 59.6% corn silage and 40.4% concentrate on a dry matter basis. The equation that determined the relationship between EBW and BW was EBW = (0.861 ± 0.0031) × BW. The relationship between empty body gain (EBG) and average daily gain (ADG) was demonstrated by the following equation: EBG = (0.934 ± 0.0111) × ADG. Net energy for maintenance (NEM) was 74.8 ± 2.89 kcal/kg of EBW0.75 per day, and metabolizable energy for maintenance (MEM) was 120.8 kcal/kg of EBW0.75 per day. The detected efficiency of use of metabolizable energy for maintenance (km) was 61.9%. The equation used to estimate net energy for gain (NEG) was as follows: NEG = (0.049 ± 0.0011) × EBW0.75 × EBG0.729 ± 0.0532. The efficiency of use of metabolizable energy for gain (kg) was 35.7%. The metabolizable protein for maintenance (MPM) was 3.05 g/kg of BW0.75. The equation used to estimate net protein requirements for gain (NPG) = (87.138 ± 65.1378 × EBG) + [(40.436 ± 21.3640) × NEG]. The efficiency of use of metabolizable protein for gain (k) was 35.7%. We concluded that the estimates of energy and protein requirements presented herein are more appropriate than the National Research Council dairy cattle model and the Brazilian BR-CORTE system to balance the diets of crossbred (Holstein × Gyr) growing bulls. [ABSTRACT FROM AUTHOR]

The objective was to quantify the energy and protein nutritional requirements of Holstein × Gyr crossbred preweaned dairy calves until 64 d of age. Thirty-nine Holstein × Gyr crossbred male calves with an average initial live weight (mean ± SEM; for all next values) of 36 ± 1.0 kg were used. Five calves were slaughtered at 4 d of life to estimate the animals' initial body composition (reference group). The remaining 34 calves were distributed in a completely randomized design in a 3 × 2 factorial arrangement consisting of 3 levels of milk (2, 4, or 8 L/d) and 2 levels of starter feed (presence or absence in diet). At 15 and 45 d of life, 4 animals from each treatment were subjected to digestibility trials with total collection of feces (for 72 h) and urine (for 24 h). At 64 d of age, all animals were slaughtered, their gastro-intestinal tract was washed to determine the empty body weight (EBW; kg), and their body tissues were sampled for subsequent analyses. The net energy requirement for maintenance was estimated using an exponential regression between metabolizable energy intake and heat production (both in Mcal/EBW0.75 per d) and was 74.3 ± 5.7 kcal/EBW0.75 per d, and was not affected by inclusion of starter feed in the diet. The metabolizable energy requirement for maintenance was determined at the point of zero energy retention in the body and was 105.2 ± 5.8 kcal/EBW0.75 per d. The net energy for gain was estimated using the EBW and the empty body gain (EBG; kg/d) as 0.0882 ± 0.0028 × EBW0.75 × EBG0.9050±0.0706. The metabolizable energy efficiency for gain (kg) of the milk was 57.4 ± 3.45%, and the kg of the starter feed was 39.3 ± 2.09%. The metabolizable protein requirement for maintenance was 3.52 ± 0.34 g/BW0.75 per d. The net protein required for each kilogram gained was estimated as 119.1 ± 32.9 × EBW0.0663±0.059. The metabolizable protein efficiency for gain was 77 ± 8.5% and was not affected by inclusion of starter feed in the diet. In conclusion, the energy efficiency for gain of milk is higher than that of starter and the net protein required per unit protein gain increases with empty body weight. [ABSTRACT FROM AUTHOR]

This study investigated the effects of increased nutrient intake levels on prepubertal mammary parenchyma development in crossbreed (Holstein × Gyr) dairy heifers. Eighteen heifers age 3 to 4 mo were fed 1 of 3 nutrient intake levels (n = 6 per treatment) designed to sustain an average daily gain of 0.0 kg/d (maintenance, MA), 0.5 kg/d (low gain, LG), or 1.0 kg/d (high gain, HG). Serum blood samples collected on d 42 and 84 after a 12-h fast were analyzed for triglycerides, leptin, insulin, and insulin-like growth factor 1 (IGF-1). Liver and mammary parenchyma were biopsied on d 42 and harvested on d 84 for gene expression analysis. Parenchyma samples were also used for biochemical and histological analysis. Mammary parenchyma weight was lower in HG than in MA or LG heifers, but mammary extraparenchymal fat was greater in HG heifers than in other groups. Heifers fed the HG diet had a greater fraction of ether extract in their parenchyma than the others and a smaller fraction of crude protein in their parenchyma than MA heifers. Moreover, the HG and LG heifers had greater body fat mass than MA heifers. Nutrient intake level had no effect on the number of intraparenchymal adipocytes. Heifers fed the HG diet had greater serum IGF-1 than the others, and serum insulin was lower in the MA than the HG or LG heifers. Liver GHR, IGF1, and IGFBP3 mRNA expression was higher, but IGFBP2 mRNA was lower in HG heifers than in others. The parenchyma mRNA expression of lipogenic markers, such as CD36, ACCA, FASN, and ADIPOR1, was upregulated by nutrient intake level. Significant nutrient intake × time interactions for lipogenic genes during the experimental period indicated variable gene expression depending on the time point of prepubertal mammary gland development. Overall, our data suggest that enhancing nutrient intake increased body fat accumulation and lipogenesis in the mammary gland to the detriment of parenchyma growth. Moreover, increased lipogenesis in the parenchyma of HG heifers may indicate that fat accumulation occurred because of adipocyte hypertrophy and not differences in adipogenesis. The implications of these results for milk yield needs to be elucidated. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the oxygen pulse and heart rate (O2P-HR) technique using the respiration chamber (RC) and comparative slaughter (CS) methods for measuring the heat production (HP) of crossbred (Holstein × Gyr) yearling bulls. Twenty-four bulls were used. Six bulls were slaughtered at the beginning of the experiment as a reference group to estimate the initial empty body weight (BW) and energy content of the remaining animals. The remaining bulls were assigned to a completely randomized design with 3 levels of dry matter intake, with 6 replicates. The levels of dry matter intake were 1.2% of BW, 1.8% of BW and ad libitum, with target orts of 5%. The bulls were fed a diet consisting of 59.6% corn silage and 40.4% concentrate on a dry matter basis. The HP (kcal/BW0.75) was measured using 3 techniques, first using O2P-HR, followed by the RC and CS methods. The HP did not differ among assessed techniques, averaging 162.7 kcal/BW0.75. The intercepts of the linear regressions (mean ± SE) were 64.82 ± 25.515 (H0: intercept = 0; P = 0.024), 33.77 ± 13.418 (H0: intercept = 0), and 50.02 ± 27.495 (H0: intercept = 0) for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The slopes of the linear regressions were 0.59 ± 0.153 (H0: slope = 1), 0.88 ± 0.081 (H0: slope = 1), and 0.62 ± 0.155 (H0: slope = 1) for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The coefficients of determination were 0.52, 0.90, and 0.52 for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The concordance correlation coefficients, 0.70 and 0.68, were moderate for O2P-HR versus RC and O2P-HR versus CS, respectively, but high, 0.90, for CS versus RC. The between-animal coefficient of variation was greater for the O2P-HR method (16.6%) compared with RC (7.7%) or CS (6.7%). We conclude that there was an agreement among the HP measurements detected using the assessed methods and that O2P-HR is able to predict HP in cattle with great accuracy but only moderate precision. Therefore, the O2P-HR method may have limitations in terms of assessing HP in low numbers of replications due to greater between-animal coefficient of variation than either the RC or CS methods. [ABSTRACT FROM AUTHOR]

A respiration system consisting of 4 climate-controlled chambers and 1 set of flowmeters and analyzers was constructed and validated. Each chamber had volume of 21.10 m3 (3.68 × 2.56 × 2.24 m) and was made from steel with double-glazed windows on either side enabling visual contact between animals. The chambers are independently climate-controlled and can maintain temperature and relative humidity in a range from 5 to 45°C and 30 to 80%, respectively. A flow generator and mass flowmeter continuously pull air from each chamber and a slight negative pressure inside the chamber is ensured. Air from all chambers and ambient air share a common gas analysis and data acquisition system for monitoring O2, CO2, and CH2 concentrations over the measurement period, with the cycle time set to 20 min. Analyzers are regularly calibrated and the chambers have mean recoveries of 99.0 and 98.0% for CO2 and CH2, respectively. The chambers are equipped with infrared cameras and electronic feed and water bins for intake measurements, as well as sensors for monitoring animal position and heart rate. Data acquisition and analysis software is used to calculate the rate of consumption of O2 and production of CO2 and CH2. The dynamic respiration measurements are integrated with feed intake data and other sensors. The daily gas exchanges are estimated by integration to determine methane emission and heat production. We conducted a trial with 12 lactating 3/4 Holstein × 1/4 Gyr crossbred dairy cows (6 multiparous and 6 primiparous) under 2 feeding regimens (ad libitum or restricted) to validate the system. Two 22-h respiration measurements were obtained from each cow. Restricted-fed cows showed lower values for milk yield, methane emission, and heat production compared with ad libitum-fed animals. We found no difference between groups for CH2 produced per kilogram of dry matter intake. Repeatability for CH2 emission and heat production was high (0.97 and 0.92, respectively). The respiration system described herein is a useful tool for measuring the dynamic and accumulated data of heat production, methane emission, and feed intake. [ABSTRACT FROM AUTHOR]

This study investigated effects of maternal overnutrition on gonadal development and pituitary-gonadal gene expression in cattle fetuses at mid- and late-gestation. Twenty-seven multiparous dry cows were fed either high (ad libitum, H) or moderate (M) intake of the same diet. Twelve cows from H (n = 6) and M (n = 6) intake carrying females fetuses were euthanized at 199 and 268 d of gestation (DG; n = 3 for H or M on each DG). Fifteen cows from H (n = 6) and M intake (n = 9) carrying male fetuses were euthanized at 139, 199, and 241 DG (n = 2 for H and n = 3 for M on each DG). Fetal gonads and pituitary gland were sampled for gene expression and histological analyses. Sex-specific responses to maternal intake were observed. Primordial and total follicle numbers were lower in fetal ovaries from H than in M intake cows. These results were the reverse for preantral and antral follicles. Volumetric proportion and diameter of seminiferous cord were lower in fetal testis of H than M intake cows. The expression level of FSHB was greater in pituitary gland of the female fetus from H compared with M intake cows, irrespective of DG, whereas LHB gene expression did not differ. In males, FSHB and LHB gene expression levels were similar between maternal intake groups. Fetal ovarian expression of P450 aromatase, StAR, BMPR2, TGFBR1, GDF9, FSHR, Bax, and CASP3 genes were higher in H than in M intake cows, irrespective of DG. Fetal testicular expression of StAR, HSD17B3, IGF1, IGF2, and IGF1R genes was higher in M than in H intake cows. The differences in gene expression for steroidogenesis, folliculogenesis, and apoptosis may explain the distinct pattern of follicular growth between offspring of M and H intake cows. By contrast, the lower volumetric proportion, diameter, and length of seminiferous cord may relate to decreased gene expression in fetal testis from H intake cows. In conclusion, maternal H intake seems to affect fetal ovarian follicular growth and number of follicles, which may affect the size of ovarian reserve in their offspring. In male fetus, maternal H intake seems to disturb testicular development and may have implications on sperm production. The underlying mechanism of differential gene expression and the effect on offspring reproductive potential should be the focus of further research, especially considering larger sample size, reducing the chance for type I errors. [ABSTRACT FROM AUTHOR]

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 freest all-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 5 d 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 250 g (25,635 ± 2,428 and 25,391 ± 2,428 g 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 freest all-housed dairy cows. [ABSTRACT FROM AUTHOR]

This study investigated the influence of day of gestation (DG) and feeding regimens (FR) on maternal and fetal visceral organ mass in Holstein x Gyr cows. Forty-four pregnant multiparous Holstein x Gyr cows with an average initial body weight of 480 ± 10.1 kg and an average initial age of 5 ± 0.5 yr were allocated to 1 of 2 FR: ad libitum (AL; n = 20) or maintenance level (ML; n = 24). Maintenance level was considered to be 1.15% of body weight (dry matter basis) and met 100% of the energy requirements; AL provided 190% of the total net energy requirements. Cows were individually fed a corn silage and concentrate-based diet composed of 93% roughage and 7% concentrate (dry matter basis) as a total mixed ration twice daily. Pregnant cows were slaughtered at 4 DG: 139 (n = 11), 199 (n = 11), 241 (n = 11), and 268 (n = 11) d, which was followed by necropsy. Mass of heart, liver, and gastrointestinal tract was heavier in AL- than in ML-fed cows. Mammary gland mass was heavier in AL- than in ML-fed cows, and the heaviest mass was observed at 268 d of gestation. Feeding regimen did not influence fetal body weight in this study. The majority of the visceral organ masses were similar in fetuses from cows fed AL or ML. These data indicate that maternal feed restriction does not affect the development of most fetal organs or fetal development; however, some maternal organs are affected by the FR provided. Moreover, the negative effect on mammary gland mass caused by ML feeding will probably not affect the subsequent lactation because the crude protein concentration in the mammary gland increased with ML feeding. However, we suggest that the AL diet in pregnant dry cows should be provided with caution because the amount of fat in the mammary gland increased at 268 d of gestation. [ABSTRACT FROM AUTHOR]