ABSTRACT. The effects of the salt-to-metal catalyst ratio and amount of digestion mixture on total nitrogen content in different materials using the Kjeldahl method were evaluated. Four samples with low nitrogen contents and four samples with high nitrogen contents were analyzed. The study evaluated two ratios of salt (sodium sulfate) to metal catalyst (copper sulfate) in the digestion mixture (10:1 and 20:1) and three amounts of digestion mixture per sample (1.0, 1.5, and 2.0 g 200 mg -1). There was an interaction between low-nitrogen material and amount of digestion mixture on nitrogen contents. Samples of cattle feces and corn presented higher nitrogen content when 1.5 and 2.0 g of digestion mixture were used. The high-nitrogen materials presented higher nitrogen contents when 2.0 g of the digestion mixture was used. However, there was an interaction between high-nitrogen material and the ratio of the digestion mixture components. The cattle carcass sample showed higher nitrogen content when the 20:1 ratio was used. The digestion mixture amount in the Kjeldahl method must be 2.0 g with a salt-to-metal catalyst ratio of 20:1 when samples of approximately 200 mg are analyzed.

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This meta-analysis aimed to identify knowledge gaps in the scientific literature on future fetal-programming studies and to investigate the factors that determine the performance of beef cows and their offspring. A dataset composed of 35 publications was used. The prenatal diet, body weight (BW), average daily gain (ADG) during pregnancy, and calf sex were elicited as possible modulators of the beef cows and their offspring performance. Then, the correlations between these variables and the outcomes of interest were investigated. A mixed multiple linear regression procedure was used to evaluate the relationships between the responses and all the possible explanatory variables. A knowledge gap was observed in studies focused on zebu animals, with respect to the offspring sex and the consequences of prenatal nutrition in early pregnancy. The absence of studies considering the possible effects promoted by the interactions between the different stressors’ sources during pregnancy was also detected. A regression analysis showed that prenatal diets with higher levels of protein improved the ADG of pregnant beef cows and that heavier cows give birth to heavier calves. Variations in the BW at weaning were related to the BW at birth and calf sex. Therefore, this research reinforces the importance of monitoring the prenatal nutrition of beef cows.

Our objectives were to evaluate the variability among animals regarding to the degradation rate of the potentially degradable fraction of dry matter, crude protein, and neutral detergent fiber, as well as to establish the minimum number of animals and provide a standardized design of sampling times for in situ ruminal degradation assays of tropical feeds with cattle. Seven feeds were evaluated, four concentrates and three forages. The incubations were performed using five rumen-cannulated Nellore heifers (328 ± 9.8 kg of body weight). The complete sets of incubation sampling times encompassed 16 time points for forage samples (0–240 h) and 13 time points for concentrate samples (0–144 h). The profiles were adjusted using both fixed and mixed model approaches. When the variation among animals on the degradation rate was considered using the mixed model approach, the precision of the adjusted degradation profiles was increased. Moreover, the utilization of a low number of animals increases the probability to obtain biased estimates of degradation rate and increased random variances. A minimum of three animals is recommended for in situ trials with cattle. Minimum designs of sampling times regarding number and position of incubation times were proposed, discussed, and recommended to assess the dynamics of tropical feed degradation.

Research on the use of heart of palm by-product (HPB) as a feed for dairy cattle is needed since it is a lowcost alternative in addition avoiding environmental contamination. The objective of this study was to evaluate intake, digestibility, milk yield and composition from cows fed HPB. Sixteen Holstein cows were used. Treatments consisted of fresh sugarcane replacement (dry matter basis -DM) of HPB at levels 0%, 7.5%, 15% and 22.5%. Experimental design was randomized blocks with measures repeated in time, and data were compared by linear, quadratic and cubic contrasts. A decreasing linear effect of HPB was observed on DM, organic matter (OM), crude protein and non-fibrous carbohydrates intakes and on digestibility of DM and neutral detergent fibre. A quadratic effect was observed for metabolizable energy intake and OM digestibility. Milk yield and composition were not affected by levels of HPB added to the diet. A cubic effect was detected for fat-corrected milk (FCM) and energycorrected milk (ECM). HPB is detrimental to intake and digestibility, but the 7.5% replacement level of HPB is recommended depending on the milk production level, since rumen environment was improved, leading to greater FCM and ECM yields at lower production costs.

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We aimed to test the associative effects among forages, and between forage and concentrates on the in vitro digestibility of dry matter and neutral detergent fibre using an artificial ruminal fermentation system. The study consisted of two assays, in which associative effects were evaluated among three forages, sugarcane, maize silage, and Tifton 85 hay under two incubation conditions (single feed or all feeds together in a jar), and the associative effects between sugarcane and soybean meal and/or ground maize. For the first assay, sugarcane digestibility increased (p < 0.02), whereas the maize silage digestibility decreased (p < 0.01) when forages were incubated together in the same jar. Tifton hay digestibility was not altered (p ≥ 0.57) by the incubation condition. In the second assay, the sugarcane digestibility was depressed (p < 0.05) when the forage was incubated along with maize grain. For both assays, the pattern of repeatability for digestibility estimates presented an influence of the incubation condition. We concluded that the incubation of different feeds together in the same jar using artificial fermenters causes associative effects among them. These effects can influence the estimates of in vitro dry matter and fibre digestibility and alter their repeatability.

A survey to explore the challenges and opportunities for dairy farm data management and governance was completed by 73 farmers and 96 non-farmers. Although 91% of them find data sharing beneficial, 69% are unfamiliar with data collection protocols and standards, and 66% of farmers feel powerless over their data chain of custody. Although 58% of farmers share data, only 19% of them recall having signed a data share agreement. Fifty-two percent of respondents agree that data collected on farm belongs only to the farmer, with 25% of farmers believing intellectual property products are being developed with their data, and 90% of all said companies should pay farmers when making money from their data. Farmers and non-farmers are somewhat concerned about data ownership, security, and confidentiality, but non-farmers were more concerned about data collection standards and lack of integration. Sixty-two percent of farmers integrate data from different sources. Farmers’ most used technologies are milk composition (67%) and early disease detection (56%); most desired technologies are body condition score (56%) and automatic milking systems (46%); most abandoned technologies are temperature and activity sensors (14%) and automatic sorting gates (13%). A better understanding of these issues is paramount for the industry’s long-term sustainability.