Ruminants

The aims of the current study were to characterize the natural compounds of Salsola tragus via GC-MS and determine its effects as a forage source on lamb growth, in vitro rumen fermentation kinetics, carcass quality, cellular damage, and metabolomic meat interaction. Twenty-one Rambouillet lambs were randomly assigned to one of three experimental diets (seven lambs per treatment): (1) a control diet (W/o-Salsola) containing 300 g/Kg dry matter (DM) of sorghum stover; (2) a diet with a medium inclusion of Salsola tragus (15-Salsola), which contained 150 g/Kg DM of Salsola tragus and 150 g/Kg DM of sorghum stover; and (3) a diet comprising 300 g/Kg of Salsola tragus (30-Salsola). The results showed there were no differences (p > 0.05) in lamb growth performance during the fattening phase. The in vitro gas analysis demonstrated that the 30-Salsola treatment increased lag time h⁻¹ (p < 0.05) and reduced gas production (p = 0.03). The metabolomic analysis findings suggest that the treatments that included Salsola tragus significantly positively affect the metabolomic composition of meat (p < 0.05). The use of 15-Salsola as a source of forage is promising for feeding lambs during the fattening phase. Full article

A key factor in calculating dairy cows’ nitrogen (N) excretion is knowing the amount of daily excreted urine. The present study aimed to investigate two methods to calculate the daily urine volume (UV) excreted using spot urine samples. Data were obtained from nine balance experiments involving 47 lactating and seven non-lactating German Holstein cows, with an average body weight (BW) of 620 ± 95 kg and an average age of 5.6 ± 1.4 years. Daily urinary creatinine (Cr) and UVs were known for all animals. The first method was developed by linearly regressing the daily excreted amount of Cr in urine against BW (p < 0.001; R² = 0.51; RSE: 2.8). The slope of the regression was used to calculate UV. The second method includes a non-linear regression of UV on Cr concentration in urine, allowing direct estimation of UV without knowledge of BW (p < 0.001; RSE: 8.13). Both estimation methods were compared to the standard method to determine UV from balance trials using Lin’s concordance correlation coefficient (CCC) and Bland–Altman plots. The first method had a CCC of 0.81, and the second method had a CCC of 0.85. Both methods can confidently be applied to calculate UV. Therefore, the second method is usable if BW is unavailable. Full article

Overmilking occurs when the teat cups remain attached to the udder during milking, even though there is little or no milk flow. This puts pressure on the teat tissue and reduces milk production due to longer milking times, meaning fewer cows are milked per hour. Therefore, the correct removal of the teat cup at the end of mechanical milking is crucial for the milking process. The aim of this study was to describe the factors influencing automatic teat cup removal (ATCR) at the end of mechanical milking and to demonstrate its importance for udder health, milk production and milk quality. There are considerable differences between milking system suppliers and countries regarding the minimum removal of the teat cup at the end of the milking process. However, to ensure good milk quality, prevent teat damage and reduce the risk of mastitis, it is important to shorten the working time of the milking machine on the udder in both automatic and conventional milking systems. For this reason, several studies have shown that increasing the milk flow switch point effectively reduces milking time, especially in automatic milking systems where dairy cows are milked more than twice a day. However, when the ATCR setting was increased above 0.5 kg·min⁻¹, milk production decreased, and the number of somatic cells in the milk produced increased. Therefore, the use of ATCR at a milk flow rate of 0.2 kg·min⁻¹ significantly increased milk production, improved milk quality and maintained udder health when a low vacuum level (34–36 kPa) was used in milking machines such as MultiLactor and StimuLactor (Siliconform, Germany). In conclusion, ATCR at a milk flow of 0.2–0.3 kg·min⁻¹ is a useful level to achieve various goals on dairy farms when a low vacuum of 34–36 is used in the milking machine. If the milking machine uses a higher vacuum, it is possible to program a higher ATCR at a milk flow of up to 0.5 kg·min⁻¹. Full article

The 8th revised edition of the Nutrient Requirements of Beef Cattle was released in 2016, with the recommendations provided in the publication being used extensively in both research and production settings. In the context of research needs identified in that publication, our objective was to review research on beef cattle nutrient requirements published since 2016 and identify knowledge gaps that should be addressed. Relative to energy requirements, the effects of environmental temperature and grazing activity, along with stress and disease, on maintenance requirements are inadequately characterized or defined. In addition, relationships between retained energy and protein should be more fully elucidated, and additional guidance on body weight at a target compositional endpoint is needed. Areas of continuing concern include accurately and precisely predicting microbial protein supply, predicting N recycling, and the metabolizable protein requirements for maintenance. Mineral and vitamin requirements are often challenging because of a lack of consistency in models used to determine requirements and potential effects of unique production settings on requirements. Based on recent research with feedlot cattle, zinc and chromium requirements should be examined more closely. Because predictions of dry matter intake are critical to supplying nutrients, additional development of prediction equations is needed, especially for beef cows and grazing beef cattle in general. Given considerable research in prediction of greenhouse gases, reevaluation of 2016 recommendations is warranted, along with a need for the updating of equations to predict excretions of N and P. Composition of feeds, particularly byproducts from ethanol production or other industrial streams, represents a knowledge gap, with obtaining reliable energy values of these feeds being a notable challenge. Nutritional models provide the means to integrate nutrient requirement recommendations into practice, and moving towards mechanistic models that take advantage of artificial intelligence and precision livestock farming technologies will be critical to developing future modeling systems. Full article

This study aimed to evaluate the microbiological quality of colostrum on three dairy farms with different colostrum management hygiene practices and to compare it with the current colostrum quality guidelines. On farm A, colostrum was fed raw, while on farms B and C it was heat treated. On farms A and B, the feeding equipment was cleaned manually, while on farm C, an automated cleaning system was used. Samples were collected from the calf-feeding equipment and submitted for microbial culture: total plate count (TPC); total coliform count (TCC); and E. coli, enterobacteria (ENTB), staphylococci (STAP), and lactic acid bacteria counts. In addition, pH, water activity (a_W), and Brix were analyzed. Colostrum quality was defined as follows: good quality (GQ)—TPC < 100,000, TCC < 10,000, STAP < 50,000 cfu/mL, and Brix ≥ 22%; excellent quality (EQ)—TPC < 20,000, TCC < 100, STAP < 5000 cfu/mL, and Brix ≥ 25%. Mean concentrations were as follows: TPC was 3.99 × 10⁵ cfu/mL (min: 40.00, max: 1.32 × 10⁷ cfu/mL); TCC was 1.17 × 10⁴ cfu/mL (min: <detection limit, max: 6.37 × 10⁵ cfu/mL); and STAP was 1.77 × 10⁴ cfu/mL (min: <detection limit, max: 3.50 × 10⁵ cfu/mL). Approximately 54% (GQ) and 32% (EQ) of samples met the defined criteria. Farm C consistently showed lower microbial counts across all culture types. Colostrum from farm B had lower TCC, LAB, and E. coli counts than farm A but not TPC, STAP, and ENTB. These results showed that a considerable proportion of calves were fed colostrum with suboptimal quality, especially when less rigorous hygiene practices were implemented. Full article

Understanding the genetic and phenotypic basis of economically important traits is essential for designing effective breeding programs in livestock. This study aimed to evaluate the phenotypic performance and estimate genetic parameters for one reproductive trait—litter size at birth (LSB)—and three pre-weaning growth traits—birth weight (BW), weaning weight (WW), and average daily gain (ADG)—in a population of 1888 Zaraibi kids born between 2018 and 2023. Genetic parameters were estimated using animal models implemented in the MTDFREML software. The overall least squares means (±standard error) for LSB, BW, WW, and ADG were 2.22 ± 0.02, 2.03 ± 0.01 kg, 10.22 ± 0.05 kg, and 90.00 ± 0.50 g/day, respectively. Statistical analyses indicated that month of birth, year of birth, and type of birth had significant (p < 0.05) effects on all traits, while the sex of the kids had no significant effect (p > 0.05) on LSB. Direct heritability estimates (h²_d) derived from Model 1 (including additive genetic, permanent environmental, and residual effects) were 0.13 ± 0.01 for LSB, 0.30 ± 0.04 for BW, 0.38 ± 0.01 for WW, and 0.30 ± 0.10 for ADG. Under Model 2 (which incorporated maternal genetic effects and their covariance with direct genetic effects), maternal heritability (h²_m) estimates for LSB, BW, WW, and ADG were 0.05 ± 0.01, 0.15 ± 0.01, 0.12 ± 0.01, and 0.14 ± 0.01, respectively. Overall, the results emphasize the importance of maternal genetic effects in influencing pre-weaning growth traits. Therefore, maternal genetic components should be explicitly considered in genetic evaluation and selection strategies aimed at improving early growth performance in Zaraibi goats. Full article

The conservation of local breeds plays a strategic role in maintaining genetic variability, ensuring adaptive responses to environmental challenges, and preserving the cultural and socioeconomic structures of traditional communities. In this context, this study explores the potential disappearance of traditional knowledge about local breeds from an ethnozootechnical perspective. The objectives were (I) to establish the breeding history of goat and sheep breeds/ecotypes in the semi-arid region of Paraíba; (II) to estimate the diversity index; and (III) to evaluate the selection criteria used by local communities in four territories: Coletivo, Borborema, Folia, and Casaco. The study aims to support genetic conservation and improvement programs. Data collection was participatory, involving breeders from all territories. To recover the breeds’ history, questionnaires were applied to the oldest breeders, called the “guardians.” Two workshops were held to assess the diversity of breeds in the past landscape (PP) and current landscape (PA), using the Recall technique. Responses were recorded in spreadsheets for analysis. Descriptive statistics and multiple correspondence analysis (MCA) were used to assess animal distribution. The Shannon index indicated a drop in goat breed diversity, from 1.3 (PP) to 0.87 (PA). For sheep breeds, it decreased slightly from 0.7 to 0.66. Breeders reported valuing traits such as adaptability, disease resistance, fertility, and conformation. Their strong emotional connection with the animals highlights the breeds’ cultural relevance. A strong connection was found between the loss of genetic material in the studied territories and the extinction of local communities’ knowledge about local breeds. Full article

Cytokine and Anti-Müllerian Hormone (AMH) profiling were performed in prepubertal Murrah buffalo heifers’ post-progesterone supplementation and Co-synchronization (Co-synch) protocol. Cytokine (IFNγ, IL6, IL1, IL13, TNFα, and TGFβ), AMH, progesterone, and estrogen hormone estimations were conducted. The ovarian follicular pattern and fertility outcome were recorded. Eighteen prepubertal heifers, 15–17 months of age, 250–300 kg body weight (BWt) were randomly divided into three groups, Group 1: n = 6, supplemented with altrenogest 0.044 mg/kg BWt/day/heifer orally for 14 days along with Co-synch program; Group 2: n = 6, implanted Controlled Internal Drug Release (CIDR) for 14 days and co-synch program, Group 3: n = 6, received Co-synch program. Ultrasonography was performed to determine ovarian follicle status on respective days of sampling. Pregnancy diagnosis was performed around 45 and 60 days post artificial insemination (AI). The Estradiol 17-β level remained constant in Group 1, Group 2, and Group 3 during the progesterone treatment and Co-synch treatment. Estradiol levels during Co-synch were significantly less (p = 0.024) on day 9 of Co-synch (14.41 ± 1.97 pg/mL) than on day 0 (20.11 ± 0.36 pg/mL) and on day 7 (19.77 ± 0.34 pg/mL) in prepubertal buffalo heifers in Group 1. However, no significance was observed in other groups. Progesterone levels in buffalo heifers subjected to synchronization protocols varied significantly (p < 0.05) on day 7 of progesterone (P4) treatment between Group 1, Group 2, and Group 3. Supplementation of altrenogest showed a significant (p = 0.043) increase in progesterone levels by day 14 of altrenogest treatment. Progesterone varied significantly in all groups on day 9 of Co-synch protocol [Group 1 (p = 0.020), Group 2 (p = 0.041), and Group 3 (p = 0.007)]. Cytokine IFNγ showed high correlation with progesterone, indicating the role of IFNγ in puberty in buffalo heifers (r = 0.626, p < 0.01). Anti-Müllerian Hormone had a significant positive correlation when supplemented with altrenogest with IFNγ (r = 0.673, p < 0.01) and TGFβ (r = 0.463, p < 0.01), whereas it was a negatively correlated with TNFα (r = −0.34, p < 0.05). Based on Karl Pearson correlation coefficients, IL13 and TGFβ could be considered as markers for puberty in buffalo heifers. Full article

The objective of this study was to evaluate whether the addition of fibrolytic enzymes to the diet of cattle in confinement improves feed digestibility weight gain; as well as evaluating the profile of fatty acids in the ruminal environment and in meat fatty acids profile. In total, 24 male dairy cattle (Holstein) aged 8 months and weighing an average of 212 kg, were divided into 2 groups: control (without additive) and treatment (0.25 g of enzymes/kg of dry matter of total diet). The experiment lasted 120 days. The first 20 days are allocated for the adaptation period. During the study, samples of blood, ruminal fluid, and feces were collected, as well as weighing the cattle and measuring their daily feed consumption. There was no effect of treatment on body weight, feed intake, feed efficiency, and nutrient digestibility (p > 0.05). Cholesterol levels were higher in the serum of cattle that consumed the enzyme; serum amylase activity was higher in cattle that received the additive only on day 120 of the experiment (p < 0.05). There was a greater amount of volatile fatty acids in the ruminal fluid, combined with a greater amount of acetic acid. The amount of fat in the meat of cattle that consumed fibrolytic enzymes was higher compared to the control group (p < 0.05). Meat from cattle in the treatment group had lower amounts of saturated fatty acids and higher amounts of unsaturated fatty acids (p < 0.05). The fibrolytic enzymes addition altered rumen fermentation in such a way that lipid metabolism was changed, which had a serious impact on cholesterol and tissue levels, that is, in the meat that had a greater amount of total lipids, an unsaturated fat. Full article

This study evaluated the effects of organic trace mineral supplementation on growth performance, antioxidant indices, mineral status, and diarrhea incidence in dairy calves raised in arid climates. Twenty-five male Holstein calves were randomly assigned to five dietary treatments for 21 days, as follows: (1) control group (no organic mineral supplementation), (2) copper-methionine (Cu-Met) supplemented diet, (3) zinc-methionine (Zn-Met) supplemented diet, (4) manganese-methionine (Mn-Met) supplemented diet, and (5) Zn-Met + Cu-Met + and Mn-Met in a premix supplemented diet. Mineral supplementation had no effect on final body weight or average daily gain. However, the concentrations of Zn, Cu, and Mn significantly increased (p < 0.01) in blood and feces of treated animals. The highest blood concentrations of Zn and Mn were observed in calves receiving Zn-Met, while Mn-Met supplementation significantly influenced blood Cu levels. The highest Zn excretion was recorded in calves receiving the organic mineral premix, whereas the highest Mn and Cu excretion was observed in the Cu-Met group. Additionally, mineral supplementation enhanced total antioxidant capacity and superoxide dismutase activity in plasma samples (p < 0.01). These findings suggest that organic mineral supplementation could be an effective strategy to improve mineral bioavailability and support the health of dairy calves during early life in arid climates. Full article

Virtual fencing (VF) technology represents an innovative approach to livestock management, utilizing GPS-enabled collars to establish invisible boundaries through auditory and mild electrical stimuli. While VF offers potential benefits such as enhanced pasture management flexibility and reduced labor costs, its widespread adoption faces challenges including high initial investment costs, connectivity issues, GPS accuracy limitations, potential device durability concerns, and individual animal variability in learning and response. Furthermore, despite studies showing rapid learning and generally minimal long-term welfare impacts, questions remain regarding optimizing training protocols, addressing occasional short-term behavioral disruptions and collar abrasions, assessing long-term welfare effects across diverse systems (especially intensive and dairy), and improving scalability. To comprehensively assess the potential and limitations of this technology and guide its future development and implementation, a review integrating existing knowledge on the efficacy, welfare implications, and practical applications of VF in cattle production systems is essential. This review examines the efficacy, welfare implications, and practical applications of VF in cattle production systems. Studies demonstrate that cattle rapidly learn to associate auditory cues with electrical pulses, achieving high containment rates (≥90%) within days, with minimal long-term welfare impacts as indicated by stable cortisol levels. However, short-term behavioral disruptions and occasional collar-related abrasions have been reported, particularly in dairy cattle. While VF enhances pasture management flexibility and reduces labor costs, challenges such as connectivity issues, individual animal variability, and high initial investment costs limit its widespread adoption. The findings suggest that VF is a promising tool for precision livestock farming, though further research is needed to optimize training protocols, assess long-term welfare effects, and improve scalability across diverse farming systems. Full article

Leonardite (LEO), a microbial derived product rich in humic and fulvic acids, has been tested, due to its beneficial properties for health and well-being, as a feed additive, mainly in non-ruminant species. Although there are some reports of LEO supplementation in ruminants fed with high-to medium-forage based diets, there is no information available of the potential effects of LEO in ruminants fed, under sub-tropical climate conditions, with high-energy diets during long-term fattening. For this reason, the objective of the present experiment was to evaluate the effects of LEO levels inclusion in diets for feedlot lambs finished over a long-term period. For this reason, 48 Pelibuey × Katahdin lambs (initial weight = 20.09 ± 3.55 kg) were fed with a high-energy diet (88:12 concentrate to forage ratio) supplemented with LEO (with a minimum of 75% total humic acids) for 130 days as follows: (1) diet without LEO, (2) diet supplemented with 0.20% LEO, (3) diet supplemented with 0.40% LEO, and (4) diet supplemented with 0.60% LEO. For each treatment, Leonardite was incorporated with the mineral premix. Lambs were blocked by weight and housed in 24 pens (2 lambs/pen). Treatment effects were contrasted by orthogonal polynomials. The average climatic conditions that occurred during the experimental period were 31.6 ± 2.4 °C ambient temperature and 42.2 ± 8.1% relative humidity (RH). Those values of ambient temperature and RH represent a temperature humidity index (THI) of 79.07; thus, lambs were finished under high heat load conditions. The inclusion of LEO in diet did not affect dry matter intake (p ≥ 0.25) and average daily gain (p ≥ 0.21); therefore, feed to gain ratio was not affected (p ≥ 0.18). The observed to expected dietary net energy averaged 0.96 and was not affected by LEO inclusion (p ≥ 0.26). The lower efficiency (−4%) of dietary energy utilization is an expected response given the climatic conditions of high ambient heat load presented during fattening. Lambs that were slaughtered at an average weight of 49.15 ± 6.00 kg did not show differences on the variables measured for carcass traits (p ≥ 0.16), shoulder tissue composition (p ≥ 0.59), nor in visceral mass (p ≥ 0.46) by inclusion of LEO. Under the climatic conditions in which this experiment was carried out, LEO supplementation up to 0.60% in diet (equivalent to 0.45% of humic substances) did not did not help to alleviate the extra-energy expenditure used to dissipate the excessive heat and did not change the gained tissue composition of the lambs that were fed with high-energy diets during long-term period under sub-tropical climate conditions. Full article

In 2020, the European Union endorsed its “Farm-to-Fork” strategy, emphasizing the need for transparency in the food production chain and communication of the sustainability level and nutritional value of food products to the consumer through labeling. For animal-based products, this also includes information about the husbandry systems under which the animals are raised. At the same time, people are becoming increasingly concerned both as citizens and as consumers about animal welfare issues in production species, as animal welfare is considered an integral part of sustainability and food security. This has led to the development of various enhanced animal welfare labeling schemes, initiated by public or private entities, or even as a partnership of both. Specifically for cattle, sheep, and goats, various standards have been developed and implemented in Europe, all establishing higher welfare standards compared to conventional farming, and in some cases exceeding the minimum requirements for organic farming as set by Regulation (EU) 2018/848. Most of these standards, especially those developed by NGOs advocating for animal welfare or through public initiative, were developed for semi-intensive to extensive systems. They primarily incorporate animal-based measures, including positive welfare indicators, offering a holistic approach to animal welfare evaluation. Although there is significant heterogeneity in European animal welfare standards, nearly all of them promote access to pasture, comfort, environmental enrichment, and, in some cases, even mother–young bonding. Full article

Fetal programming suggests that maternal nutrition during gestation influences offspring growth, development, and productivity. This study evaluated the effects of prenatal protein-energy supplementation on the lifetime performance of Nellore cattle. Twenty-eight nulliparous heifers were inseminated and assigned to one of two groups: Non-Programmed; receiving only mineral supplementation; or Fetal Programmed (FP); receiving additional protein-energy supplementation throughout gestation. Cows in the FP group maintained significantly better body condition score during gestation (p < 0.01), and their calves exhibited greater body weight (BW) during the first 56 days (p < 0.05) and a tendency to grow to a greater BW up to 250 days (p < 0.10) in addition to improved morphological traits, such as increased rump width and length at 45 days of age (p ≤ 0.02). However, these advantages were not sustained in later growth stages, as no significant differences were observed in final body weight, ultrasound carcass traits, or overall feedlot performance. These findings suggest that while prenatal nutrition can influence early developmental traits, its long-term impact on offspring performance may be limited under consistent postnatal management. Nonetheless, the limited sample size, combined with the absence of molecular data and individual feed intake and efficiency measurements, constrains a more comprehensive interpretation of the programming effects on offspring performance. Further research is needed to explore the molecular mechanisms of fetal programming, particularly its epigenetic effects and interactions with postnatal nutrition, to optimize strategies for improving the efficiency and sustainability of beef cattle. Full article

Enteric methane emissions from ruminants substantially contribute to global greenhouse gas emissions, necessitating effective mitigation strategies that also support animal productivity. This study assessed the efficacy of a multi-component feed additive that combines medium-chain fatty acids (MCFAs), live yeast, plant-based agents, and Vitamin B, in reducing methane emissions, improving feed efficiency, and enhancing growth and immune function in sheep. Twenty crossbred castrated male sheep (52 ± 3.7 kg) were divided into control and treatment groups (n = 10 each), with the treatment group receiving grass pellets supplemented with the multi-component feed additive (20 g/day) for 71 days, including a 30-day acclimatisation period. Feed intake, methane emissions, growth performance, and blood parameters were monitored using BioControl pens, GreenFeed units, and haematological analyses. The treatment group exhibited a 24% increase in daily feed intake (p < 0.001) and a 22.2% reduction in methane yield per kg of dry matter ingested (p < 0.001), which could be attributed to MCFAs’ anti-methanogenic properties and yeast’s rumen modulation. However, no significant improvements were observed in daily live weight gain, feed conversion efficiency, or immune parameters, suggesting limited energy utilisation for growth. These findings highlight this novel multi-component feed additive as a promising strategy for methane mitigation in forage-based systems. Further dosage optimisation and dietary integration could enhance its application across ruminant species, contributing to sustainable livestock production. Full article

Data for growth (birth, weaning and yearling weights) and carcass (longissimus muscle area, intramuscular fat percentage and depth of rib fat) traits and 50K SNP marker data to calculate the genomic relationship matrix were collected from 738 Brangus heifers. Univariate and multivariate genomic best linear unbiased prediction models based on the genomic relationship matrix and univariate and multivariate artificial neural networks models with 1 to 10 neurons, as well as the learning algorithms of Bayesian Regularization, Levenberg–Marquardt and Scaled Conjugate Gradient and transfer function combinations of tangent sigmoid–linear and linear–linear in the hidden-output layers, including the inputs from genomic relationship matrix, were created and applied for the analysis of growth and carcass data. Pearson’s correlation coefficients were used to evaluate the predictive performances of univariate and multivariate genomic best linear unbiased prediction and artificial neural networks models. The overall predictive abilities of genomic best linear unbiased prediction and artificial neural network models were low in the univariate and multivariate analysis. However, the predictive performances of models in the univariate analysis were significantly higher than those from models in the multivariate analysis. In the univariate analysis, models with Bayesian Regularization and the tangent sigmoid–linear or linear–linear transfer function combination yielded higher predictive performances than models with learning algorithms and genomic best linear unbiased prediction models. In addition, predictive performances of models with tangent sigmoid–linear transfer functions were better than those with linear–linear transfer functions in the univariate analysis. Full article

The aim of this study is to review the supplementation of polyphenol on milk composition and milk fatty acid content in dairy animal. A systematic review of literature was carried out by using Google Scholar, Scopus, and Science Direct databases. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines methodology was carried out and as a result, 21 articles were included. Results showed that polyphenol supplementation significantly affect milk saturated fatty acid content (p < 0.00001) and milk medium-chain fatty acid content (p < 0.0001). Meanwhile, polyphenol supplementation effects significantly in the subgroup of agro-industrial by-products (p < 0.05) for milk protein content, grain (p < 0.05) for milk lactose content, all the subgroup for milk saturated fatty acid content and both grain and agro-industrial by-products for milk medium-chain fatty acid content. In conclusion, milk saturated fatty acid is affected by polyphenol supplementation regardless of polyphenol sources. However, it is recommended to include more studies in future to obtained a higher heterogeneity. Full article

The estimation of body chemical composition is necessary to determine the nutrient requirements of growing/finishing cattle, but recent analyses indicate that published equations provide erroneous results when applied to diverse breed types and sexes. The objective of this analysis was to develop equations to estimate empty body and carcass chemical composition for different breed types and sexes. A dataset was developed from the published literature that contained 359 treatment means from 46 studies published between 1971 and 2021. Stepwise regression was used to develop prediction equations using Akaike’s Information Criteria to estimate empty body and carcass fat, protein, and ash concentrations (%). Empty body fat, protein, and ash could be predicted from combinations of empty body water, empty body fat, and empty body protein (RMSE = 1.53, 1.85, and 0.67; R² = 0.99, 0.98, and 0.95). Breed type and sex affected the intercept and (or) slope coefficients to predict empty body fat, protein, and ash. Carcass fat, protein, and ash could be predicted from combinations of carcass water, carcass fat, and carcass protein (RMSE = 1.77, 1.62, and 0.82; R² = 0.97, 0.98, and 0.93). Breed type and sex affected the intercept and (or) slope coefficients to predict protein and ash, but not fat. Equations adjusted for breed type and sex may be more robust than previously published equations based on a single breed or sex. Full article