Browsing by Subject "Feed intake"

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Comparison of plant cell wall degrading community in the rumen of N’Dama and N’Dama x Jersey crossbred cattle in relation to in vivo and in vitro cell wall degradation
(2004) Nouala-Fonkou, Simplice; Becker, Klaus
This thesis presents a unique combination of an in vivo feeding trial, the analysis of the microbial community structure in the rumen, and in vitro fermentation studies, in order to assess the impact of breeds and diets on animal performance in a West African production setting. Pure N?Dama and N?Dama x Jersey crossbred cattle were fed two basal diets, baby corn and groundnut hay, supplemented with graded levels of either conventional concentrate or moringa leaf meal, to compare animal responses in productivity. In this context, Moringa oleifera leaf meal constitutes a locally available, potential alternative to commercial concentrate for cattle production. The cell wall digesting community of N?Dama and its crosses was analysed using phylogenetically based hybridisation probes to account for the contribution of rumen microbes to differences in fermentation patterns and animal response. In vitro fermentation studies were carried out using the same diets and supplementation levels as fed in vivo, to test the accuracy of the in vitro gas production technique in predicting the optimum level of supplementation. The in vivo feeding experiment focussed on the comparison of breed performance with diets relevant for local production conditions. Six N?Dama and six N?Dama x Jersey (crossbred) animals were used in a cross over design. They were fed consecutively three combinations of roughage and supplement, baby corn stover and concentrate (BCS:Co), groundnut hay and concentrate (GNH:Co) and groundnut hay and moringa meal (GNH:Mo), each at 5 levels of supplementation (0, 10, 20, 30 and 40%). Results from this study showed that there was a clear difference in animal response to different feeding regimes between the two breeds. When averaged over all diets organic matter intake (OMI) was higher in crossbred compared to N?Dama (94 and 87.6 g/kg 0.75 d-1, respectively). When analyzed for the diets and averaged over the breeds OMI was higher when animals were fed the baby corn based diet compared to groundnut based diets (95 against 88 g/kg 0.75 d-1). Only when the diet consisted of BCS:Co, and at low levels of supplementation, N?Dama ingested more than crossbred, but the difference was not significant. With GNH:Co crossbred ingested significantly more at levels of supplementation less or equal to 20%. With GNH:Mo crossbred ingested more, whatever the level of supplementation. The optimum level of supplementation in vivo, estimated with the single slope broken line model, was 10% and 20% for both breeds when they were fed BCS:Co and GNH:Co respectively, but 30% for N?Dama and 10% for the crossbreds when animals were fed GNH:Mo. Organic matter digestibility (OMD) was higher in N?Dama (64.6% against 60.7% in crossbreds) when animals were fed BCS:Co and supplementation had no effect on OMD of BCS:Co whatever the breed. When animals were fed groundnut hay as basal diet, OMD was also significantly higher in N?Dama at low levels of supplementation, but the differences became insignificant beyond 10% and 20% of concentrate or moringa, respectively. With GNH:Co OMD showed a quadratic response (p<0.001) with increasing level of supplementation when it was fed to crossbreds and was not affected when it was fed to N?Dama. Increasing levels of moringa meal supplementation increased OMD in both breeds up to a peak at 20 and 30% for N?Dama and crossbred, respectively. Average daily weight gain (ADG) was not affected by the breed, however it was higher on BCS:Co compared to other diets. On BCS:Co ADG increased with the level of supplementation, reaching a peak at 30%, whereas supplementation had no effect on ADG when animals were fed groundnut hay based diets. As N?Dama could take in and digest more of the low quality BCS:Co diet, they were less efficient in feed conversion under this feeding regime (FCE: 14 vs. 9 for the crossbreds). On GNH based diets, however, N?Dama surpassed the crossbreds in feed conversion efficiency with ratios of 11 vs. 13 for GNH:Co and 9 vs. 27 on GNH:Mo. Rumen microbes play the key role for the digestibility of a given feed and thus also for feed intake and finally animal performance. Obviously, the community composition and activity is highly dependent on the diet. With the present set-up, however, with identical external conditions and three different, well defined diets fed to both, N?Dama and crossbred cattle, a comparison of the microbial community structure between breeds could be attempted. The in vivo and in vitro data taken in the other parts of the study allow a sensible interpretation of potential changes in microbial composition. Rumen fluid was collected from three fistulated N?Dama and three crossbred animals adapted to the experimental diets at medium supplementation level. The cell wall degrading community was analyzed using the phylogenetically based 16S rRNA hybridisation probes. The results showed that on BCS:Co diet the Fibrobacter and R. flavefaciens RNA concentrations were higher in rumen fluid of N?Dama compared to crossbred. These concentrations were also significantly affected by the diet, such that they were higher on baby corn stover compared to groundnut hay based diets. The results of the microbial community analysis suggested that the differences between breeds observed in digestibility could be partially explained by the composition of the cell wall degrading community. Parallel to the in vivo experiment, in vitro fermentation studies were undertaken to evaluate the predictability of the in vivo response to supplementation by the in vitro data. Rumen fluid from 3 N?Dama and 3 crossbred donor animals was used for 24 hour in vitro fermentations. The donor animals were fed consecutively the same three diets used in vivo (BCS:Co, GNH:Co and GNH:Mo) at 20% level of supplementation. Each of these inocula was incubated with in vitro substrates consisting of all the combinations tested in vivo (i.e. 3 diets, 5 levels of supplementation) plus supplement alone. This design should allow to analyze for both, the impact of donor breed as well as that of the donor diet and to conclude which factors may be varied while maintaining predictability. The breed of the donor animals did not significantly affect 24 hour gas production, but short chain fatty acid concentration was higher with rumen fluid from crossbreds when donors were fed BCS:Co and GNH:Mo. Moringa meal as supplement to donor animals changed the fermentation pattern of all the substrates, such that gas production and SCFA increased substantially in groundnut hay based substrates, whereas gas production of BCS:Co substrates decreased and SCFA did not substantially change. In vitro digestibility was higher with rumen fluid from N?Dama whatever the diet of donor animals and the substrate incubated. GNH:Mo as donor diet also increased IVTD of all the substrates. Even though there was no clear response in vivo, this indicates a general stimulation of microbial activity in the rumen and renders moringa leaf meal a promising supplement. Averaged over all data there was a positive correlation (r2=0.53 p<0.001) between IVTD and in vivo OMD. This correlation was much stronger when calculated for a specific diet (e.g. r2=0.90 p<0.001 for BCS:Co, averaged over the breeds). Analyzing the data for the individual breeds affected correlations only to a minor degree. Thus, when testing a supplementation strategy in vitro, it should be important that donor animals are fed the same components (roughage and supplement) that will be combined at different levels in vitro, whilst the breed of donor animals may be of second importance. This work provides conclusive evidence that in vitro incubations may be used to design supplementation strategies, thus reducing the need for in vivo experiments. Moringa leaf meal is a promising local resource to substitute for conventional concentrate. Differences in productivity between breeds could be correlated to (and may be partially manifested through) a divergent community structure of rumen microbes. That, in turn, indicates that animals of different breeds might have a ?genetic background? that favours the establishment of a certain community, even if the animals are kept under identical conditions. This relationship should be investigated by more advanced molecular techniques.
Modelling nitrogen use and excretion in dairy cattle herds grazing temperate, semi-natural grasslands
(2025) Perdana-Decker, Sari; Dickhöfer, Uta
Grazing-based dairy cattle systems exhibit several benefits, such as preserving biodiverse grassland habitats, improving animal welfare, or turning grassland protein into human-edible protein. However, grazing-based diets are prone to greater nitrogen (N) losses via urine than balanced stall-fed diets, leading to a greater risk for N emissions. Strategies for improving the N use in grazing-based systems are predominantly investigated on homogenous clover-ryegrass pastures with high 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 received less attention. The present thesis addressed the knowledge gap on the N use of such low-input grazing-based systems by adapting an existing dynamic, process-based herd model (i.e., the LIVestock SIMulator, LIVSIM) for simulating animal performance and N use and excretion of dairy herds. For this, a broad dataset was gathered on nine commercial organic dairy cattle farms in Baden-Württemberg during two grazing periods (2019, 2020). This dataset fulfilled two purposes: firstly, to get a basic understanding on N use and excretion of dairy cows under low-input grazing conditions (study 1); secondly, to serve as reference dataset for adapting and evaluating LIVSIM for such production systems (studies 2 and 3). The reference dataset represented the wide range of grazing and production factors found on commercial farms in South Germany using semi-natural grasslands for grazing. The dataset applied for study 1 covered n = 323 individual animal observations with mean (± one standard deviation) milk production, dry matter intake (DMI), and pasture DMI (PDMI) of 23.9 (± 5.35), 21.0 (± 3.21), and 11.3 (± 4.83) kg/d, respectively. Milk N use efficiency (MNE) averaged 24.7 g/100 g N intake (± 5.91), which is greater than observations in temperate, high-input grazing-based systems but lower than in cows receiving balanced stall-fed diets. Nevertheless, MNE and other indicators of N use and excretion varied greatly among farms and seasons, highlighting the need to identify the drivers for this variation. Supplement feeding had the greatest potential for manipulating the N use and excretion. Increasing shares of fresh forages as well as of hay of total supplement DMI increased N use (e.g., MNE) and decreased urinary N excretion (e.g., urinary N to creatinine ratio), while increasing shares of concentrates of supplement DMI were related to lower N losses via urine. Study 1 highlighted that using semi-natural grasslands for grazing can potentially reduce environmentally harmful N losses compared to high-input grazing systems. For future research endeavours, a modelling approach may simplify the investigation of more feeding scenarios, their interactions, different local conditions, and considering the spatial and temporal variation of pasture herbage quality and yield. Hence, studies 2 and 3 focused on adaptating LIVSIM for low-input grazing-based dairy farms. The DMI and N intake are among the most decisive factors for determining animal performance and N excretion. Therefore, a module for predicting the PDMI of cows grazing semi-natural grassland was identified in study 2, using a subset of the reference dataset (n = 233 individual animal observations). Among the thirteen tested models, behaviour-based and semi-mechanistic models specifically developed for grazing animals had the lowest prediction adequacy. Their underlying empirical equations likely did not fit the grazing and production conditions of farms employing semi-natural grasslands. Modelling performance of a semi-mechanistic model developed for stall-based feeding situations (Mertens II) with slight modifications was best (relative prediction error = 13.4%) when evaluated based on the mean observed PDMI (i.e., averaged across animals per farm and period (n = 28)). Consequently, the modified Mertens II model was integrated in LIVSIM in study 3. Additionally, the modules for energy requirements, lactation, N excretion, and herd management were adopted, and breed-specific model coefficients added to represent Simmental, Brown Swiss, and Holstein-Friesian cattle breeds. Dairy cow characteristics, herd composition, annual milk yield, and DMI were predicted accurately (i.e., with a relative difference ≤ 10 % between observed and predicted outputs for the majority of outputs). The absolute total N excretion (g/d) was underpredicted by 23 % (= relative difference between observed and predicted values) mainly due to the underprediction of urinary N excretion by 43 %. The relative differences in N excretion between farming systems, in contrast, were predicted reliably. The observed faecal, urinary, and total N excretion (in % of N intake) differed by 30, -23, and -7 %, respectively, between the two reference herds, which is similar to the respective relative differences for the predicted faecal, urinary, and total N excretion of 32, -36, and -4 %. Further model improvements should focus on increasing the prediction accuracy of N excretion and its partitioning due to the varying degree of susceptibility of faecal or urinary N to volatilisation and leaching. The scenario and sensitivity analyses further confirmed that the adapted LIVSIM plausibly simulated differences in animal performance and nutrient excretions based on differences in supplement feeds and pasture herbage. Core input and model coefficients are the dietary ME, CP, and rumen-undegradable CP concentrations, as well as the available herbage biomass on pastures, for which precise measurements are thus needed. The findings of studies 2 and 3 demonstrate that existing models can be adopted for low-input grazing-based dairy production systems. There is further potential for adapting LIVSIM for production systems beyond the ones investigated in the present study, and/or for adding more outputs (e.g., enteric methane) and scales (e.g., grassland) to better capture the multifaceted aspects determining farm sustainability.
Untersuchungen zur Variation und Rhythmik der individuellen Futteraufnahme bei Pekingenten in Gruppenhaltung
(2003) Bley, Tobias Alexander Georg; Bessei, Werner
Methods to record feed intake in group reared individuals were only available for larger domestic species, such as pigs and cattle. Similar equipment for ducks using an antenna-receiver system had to be developed for the present study. The antenna was fitted nearby the feeder and the transponder was attached to the wing mark. The feeders were connected to an electronic scale and the following characteristics were recorded by a PC continuously: number of the bird, day, time of day, time of visits to the feeder, feed consumption. The system was suitable for duckling from 14 days old onwards. Two experiments were carried out. In experiment 1 a total of 50 male Pekin-type hybrid from 14 to 49 days of age were used. In experiment 2 records were taken from 480 male and female ducks of an experimental line from day 21 to 45. The birds were raised in groups on deep litter (straw). Commercial pelleted feed and water were provided ad libitum. The distance between feeders and drinkers was 1 m in experiment 1 and 5 m in experiment 2. The following traits were extracted from the records: Number of meals per day (defined as visits to the feeder with feed intake) Duration of meals (sec.) Size of meals (grams.) Intensity of feeding (feed intake in grams. per min): feed intake per meal in relation to duration of meal Duration of pauses (sec. or min.) Duration of feed intake per day (min.) Feed intake per day (grams.) Live weight (grams.) Dates of a total of 530 ducks and containing 260000 visits to the feeder were recorded and analysed On the basis of the duration of the frequency of meals per day two distinct groups, birds with large number of short meals (HM), and birds with a small number of big meals (LM), were identified. Comparisons were made between the two meal-type groups for all traits and the circadian rhythms of feed intake. HM ducks were characterised by short duration and small size of meals, and short pauses between meals. There was only a small difference between the meal-types for the total duration of feeding and feeding intensity. HM birds were lighter than LM birds. With increasing age, number of meals per day and duration of feeding per day decreased while daily feed consumption increased. Duration and size of meals, and intensity of feeding increased with age. Changes in feeding activities were most important between 3 and 4 weeks of age. An effect of sex was only noted for the number of meals at seven weeks of age. Differences in the occurrence of pauses were found in response to the experiment, meal-type and age. With regard to the presentation and analysis of pauses the usual procedures using log survivorship functions were discussed. In the present study, however, the differences in the distribution of pauses have been demonstrated using the relative frequency for the pauses of long duration and the cumulative frequency for the pauses of shorter duration. With regard to the high variation of the duration of pauses among individuals and with age the calculation of a single meal criterion, which separates pauses within and between meals, for all individuals and over all ages was not considered useful. On the basis of the distribution of pauses of the different meal-types it seems that the meal criterion is less than one minute in the HM types, and over 35 minutes in the LM types. The circadian rhythm of feed intake was similar in both meal-type groups and shows a biphasic shape with maxima at the beginning and the end of the light period. There was also feed intake during the dark period, the consumption, however, was lower than in the light period. The power spectra of the feed intake showed main components in the 24; 12; 6 and 4.8 hours rhythms and, in addition, various different rhythms in the area of 2-4 hours. The rhythm pattern was more pronounced in the HM types as compared to the LM types. The power of the 24 hours rhythms decreased with age, while a 6 hours rhythm developed at the end of the test period. In general it can be said, that there are distinct types of temporal structures in feeding behaviour in ducks. Age-depending changes appear mainly in the early fattening phase up to 5 weeks of age. There is no general meal criterion in ducks which may be applied to all individuals and at all ages. Feed intake underlies rhythmic processes which are modified with age.