Fakultät Agrarwissenschaften

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Die Fakultät entwickelt in Lehre und Forschung nachhaltige Produktionstechniken der Agrar- und Ernährungswirtschaft. Sie erarbeitet Beiträge für den ländlichen Raum und zum Verbraucher-, Tier- und Umweltschutz.

Homepage: https://agrar.uni-hohenheim.de/

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Metabolic adaptation to energetic demands of early lactation in Holstein Friesian and Simmental cows
(2025) Ruda, Lena; Straub, C.; Scholz, A.M.; Huber, Korinna
Holstein Friesian (HF) is the highest-performing dairy breed worldwide. However, this breed is prone to suffer from health disorders and infertility due to metabolic instability. The aim of the study was to use the metabolic differences between to breed, German HF and German Simmental (SI), for discussion of the biological impact of well-known and novel pathways and their respective indicators. Therefore, a targeted metabolomics approach combined with an examination of classical clinical chemistry using plasma samples was used to describe the metabolic status 42 days before expected calving and at day 21 of lactation. In total, 27 multiparous cows (HF n = 17, SI n = 10) were enrolled in the study. All cows were kept on the same farm under identical management, feeding and housing conditions. BW of HF cows dropped while SI cows maintained their BW but produced less milk than HF cows during the first weeks of lactation. Differences were detected for the following indicators and related pathways, and were used to assess their biological impact. Branched-chain amino acids such as leucine and isoleucine at day +21 remained as high as at day −42 in HF cows; however, in SI cows, a clear drop in these amino acids was observed indicating less body protein mobilisation in this breed. Alpha amino-adipic acid and kynurenine as markers for oxidative stress balance were increased at day +21 in HF cows, only reflecting a metabolically more tensed condition in HF cows. As a conclusion, these findings confirm the impact of these metabolites on a higher risk to suffer from metabolic disorders.
Nitrogen excretion and utilisation of dairy cows grazing temperate semi- natural grasslands
(2024) Perdana-Decker, Sari; Velasco, Elizabeth; Werner, Jessica; Dickhoefer, Uta
Diets reliant on grazed, temperate herbage are prone to greater nitrogen (N) losses via urine than balanced stall-fed diets which poses a greater risk for N emissions. Measures for improving the N utilisation in grazing-based dairy cattle systems are predominantly investigated on homogenous clover-ryegrass pastures with high herbage yields and nutritional quality. In contrast, grazing-based systems reliant on less external inputs (e.g., synthetic fertilisers or concentrates) using semi-natural grassland as main feed source, such as in large parts of Central Europe, received less attention. The N utilisation and excretion of grazing cows in low-input dairy farms were, thus, investigated on nine commercial organic dairy farms in South Germany across one to four periods per farm. The dataset captured a diverse set of dairy production systems comprising 323 individual animal observations. A mean (± one SD) milk production, DM intake (DMI), and pasture DMI of 23.9 kg (± 5.35), 21.0 kg (± 3.21), and 11.3 kg/d (± 4.83), respectively, was determined. Feed intake was estimated using titanium dioxide and faecal CP concentration as markers of faecal excretion and diet digestibility, respectively. Milk N use efficiency (MNE; i.e., milk N secretion as share of N intake) averaged 24.7 g/100 g N intake (± 5.91), which is greater than observations in temperate, high-input grazing systems but lower than in cows receiving balanced diets in the barn. The MNE and another seven indicators of N utilisation and excretion displayed a wide range of values. The grazing management factors explaining this variation were, thus, identified via backward elimination. The supplementation strategy had the greatest potential for manipulating N utilisation and excretion of dairy cows. Increasing shares of fresh forages (i.e., meadow grass or clover-grass leys) as well as of hay in supplement DMI increased N utilisation (e.g., MNE) and decreased urinary N excretion (e.g., urinary N to creatinine ratio), while increasing shares of concentrates in supplement DMI are related to lower N losses via urine. At the same time, increases in total supplement DMI reduced N utilisation and increased urinary N excretion. Hence, full-time grazing combined with supplementation of fresh forage and hay in the barn is a viable option for low-input, grazing-based dairy operations with moderate levels of N losses.

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