Chemical composition and fatty acid profile of BRS Capiaçu ensiled at different regrowth ages

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of chopped forage and silage of BRS Capiaçu elephant grass at four regrowth ages: 50, 70, 90 and 110 days. A randomized block design with five replications was used. The ensiling was carried out manually in experimental silos without wilting using no additives or bacterial inoculants. The results were analyzed using mixed models (P < 0.05). The model included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There were linear increases in the dry matter (DM, g kg-1) and lignin (g kg-1 DM) contents and linear reductions in the in vitro DM digestibility (g kg-1) of chopped grass and silage as a function of regrowth age (P < 0.001). Quadratic effects (P ≤ 0.01) were observed for the chopped grass contents (g kg-1 DM) of crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) as a function of regrowth age. There were linear decreases (P < 0.0001) in the CP content (g kg-1 DM) and pH and linear increases (P < 0.001) in the EE and NDF contents (g kg-1 DM) in the silage as a function of regrowth age. There were linear decreases (P < 0.01) in the chopped grass contents and linear increases (P < 0.05) in the silage contents of total FAs, linoleic and α-linolenic acids (g kg-1 DM) asa function of regrowth age. BRS Capiaçu elephant grass must be harvested at up to 70 days of regrowth to obtain forage with good nutritional value and the highest levels of linoleic and α-linolenic acids (g kg-1 DM). To produce silages with adequate pH values and the highest levels of linoleic and α-linolenic acids (g kg-1 DM), BRS Capiaçu must be harvested between 90 and 110 days of regrowth.

PSXIV-38 Short-term adaptation of milk yield and feed efficiency to individualized dietary changes

Automated in-parlor feeding and other precision individual animal feeding strategies are a primary interest of efforts to enhance precision animal nutrition. Our objective was to determine short-term effects of changes in diet composition on milk yield and feed efficiency in dairy cattle. A replicated latin square with 4 groups of 6 cows was used to evaluate responses to feeding increasing amounts of ground corn (GC), soybean meal (SBM), chopped grass hay (GH), or total mixed ration (TMR) for 9 d periods. Throughout each period, treatments were top dressed at incrementally increasing rates to provide 0 to 20 percent of calculated net energy intake. Cows were group housed and fed once daily in Calan gates for 36 days. Mean milk yield, efficiency, and the linear slopes of these responses to top dress intake were analyzed during each 9 day period. Mean responses and response slopes were analyzed using a mixed-effect model with fixed effects for top dress and random effects for animal, period, and square. Milk yield was significantly affected by top dress type (P = 0.010) and GH differed significantly from SBM (P = 0.015). However, feed efficiency did not differ with top dress type. The milk yield slope was not affected by top dress type (P = 0.268), but the efficiency slope was affected (P = 0.011). The efficiency response to dietary changes was greater for added SBM than for added GH (P = 0.012), but SBM responses did not differ from GC (P = 0.484) or TMR (P = 0.772). These results suggest opportunity to use individualized, automated feeding strategies to adjust dietary composition in the short-term to target economically optimal formulations without sacrificing production.

156 Structural patterns in dairy cow efficiency responses to supplementation

The increased availability of precision technologies in dairy production systems coupled with improved computational power has increased interest in individualized feeding. The objective of this study was to determine if small groups of dairy cows with a similar response to dietary adjustment could be identified based on individual animal efficiency changes in response to short-term diet shifts mimicking automated precision feeding. A replicated latin square with 4 groups of 6 cows was used to evaluate responses to feeding increasing amounts of ground corn, soybean meal, chopped grass hay, or total mixed ration for 9 d periods. Throughout each period, treatments were top dressed at incrementally increasing rates to provide 0 to 20 percent of calculated net energy intake. Cows were group housed and fed once daily in Calan gates for 36 days. The feed to milk ratio (FtM) was calculated as feed intake per unit milk yield, so that a lower FtM was more considered efficient. To test the idea that cows could be grouped by their FtM response to different feeds, data were split by top dress type and each day’s FtM was used as a variable for each cow. Principal Component Analysis (PCA) was performed to determine cows that had the most similar FtM behaviors over the 9-day feeding period. After PCA, k-means clustering was performed on the first two dimensions from PCA to discern groups of cows in the data. This approach can inform precision feeding strategies by calculating within-group average MYE and assigning cows to whichever feeding strategy generated the lowest MYE. The fact that cattle segregate into different efficiency groups depending on the supplement type provided suggests that individualized feeding schemes must be designed with individual animal interactions with supplement type in mind.

Hydration status of horses performing endurance exercise: II. Evidence for a role of dietary fibre type, not oil supplementation

The equine large intestine has been suggested to serve as a water reservoir during prolonged exercise and may be influenced by dietary fibre source or length. At the same time, oil supplementation may result in performance and possibly hydration advantages. This study was designed to examine the effect of different fibre-based feeds, of similar particle size, on hydration status, with and without oil supplementation. Six two-year-old Arabian horses were randomly assigned to diets containing either chopped grass hay (G) or a 50:50 chopped grass hay: fibre-based chopped mix (GC) and either oil supplementation (approximately 5.7% crude fat in total diet) or no oil supplementation. Horses consumed each diet at least 21 d before completing a 60 km exercise test. Total body water, determined using deuterium oxide (D2O), was 66.1% of body mass and did not differ due to treatment. Horses consuming GC had greater (P<0.05) body mass at the start of exercise than those consuming G. Water consumption during the exercise test was greater in G than GC (P<0.01; 13.3±1.3 l, 10.9±1.3 l), as were packed cell volume (P<0.01; G 36.8±1.2%, GC 35.1±1.2%) and plasma aldosterone across all times (P<0.001; GC 0.79±0.11 pmol/l, G 1.48±0.11 pmol/l). The results suggest dietary fibre source may play a greater role in hydration status over 60 km distances than does oil supplementation. Core temperatures reported in this study were all similar to those reported in a previous study using a 50:50 long hay to chopped highly digestible fibre mix and lower than reported in previous studies using long stemmed hay or pasture suggesting the particle size or length of the fibre may have an influence and thus merit further investigation.

Findings on the cultivation of potatoes in organic farming

This paper explores the effectiveness of organic and plastic mulching for potato production in the Czech Republic. The mulching with chopped grass (GM) and black textile mulch (BTM) were compared to non-mulching control variant (C) with mechanical cultivation. Especially in plots with BTM were first formed ridges and covered by the black polypropylene non-woven textile and then they were planting. During vegetation the infestation of Colorado potato beetle (CPB), weeds biomass, course of soil temperature and soil water potential were assessed. The results showed that surface of GM had a positive effect on soil temperature reduction, soil water potential depression. This study also indicated a positive effect of GM on the larvae of CPB diminution, on the other hand higher incidence of larvae and higher defoliation was observed in BTM. GM had a significant effect on the yield of potatoes. The yield of ware potatoes was higher by 27 % higher on plots with GM and by 16 % lower on plots wit BTM in comparison with C. NeemAzal T/S decreased statistically significantly % of defoliation and increased yield of ware potatoes by 35 % in comparison with control.

Utilization of fortified cubes to deliver trace minerals and monensin in forage-based diets

The potential benefits of mineral or monensin delivery through forage cubes vs. free-choice were investigated in Simmental × Charolais pregnant cows and their calves. Thirty-six mid-gestation cows (615 ± 21 kg) placed in 18 pens were initially depleted of liver Cu reserves by feeding a TMR containing 100 mg Mo kg-1 DM and 4 g S kg-1 DM for 42 d, allowed to stabilize on a low Mo, Cu and S diet for 42 d and were then used in a mineral uptake study. Experimental diets containing chopped grass-hay were fed ad libitum with one of the following three alfalfa-barley grain cubes at 2 kg head-1 d-1: (1) no addition of mineral and ionophore (Free Choice); (2) addition of mineral and no ionophore (+M Cube); and (3) addition of mineral and ionophore in the form of monensin (+M+I Cube). Mineral intake and mineral status (through liver biopsy and blood sampling) were monitored over a 16-wk feeding period, which included the first 6 wk post-calving. Dry matter intake by Free Choice cows prior to calving was higher than that by +M Cube and +M+I Cube fed cows (P < 0.05). Pre- and post-calving mineral intake (g pen-1 d -1) by Free Choice cows was 31.6% higher than +M Cube and +M+I Cube fed cows (P < 0.01). The coefficient of variation for day-to-day and pen-to-pen variation for cows consuming free choice mineral was 81 and 36%, respectively. There was no variation in supplemental mineral intake for +M Cube and +M+I Cube fed cows due to complete consumption of all forage cubes offered. Dietary treatment did not influence mean serum Cu and Zn concentration or plasma ceruloplasmin oxidase (Cp) activity of cows (P > 0.05). However, liver Cu concentration (mg kg-1) of +M+I Cube fed cows tended to be higher than for the other treatment groups (P = 0.06). Calf ADG at 6 wk of age was not affected by dietary treatment of dams (P > 0.05). Copper and Zn status of calves at 6 wk of age was not different among dam dietary treatments. However, plasma Cp activity declined more rapidly in +M+I Cube calves compared with +M Cube calves (P < 0.05), which may be attributed to the presence of monensin in the +M+I Cube diet of late gestation cows. Fortified cubes may be used as an effective means of eliminating the variability in mineral intake associated with free choice consumption with no detrimental effect on mineral status of cows and their suckling calves. Key words: Forage cubes, trace minerals, monensin, pregnant cows, calves

Goose Production Responses to Grass-Based Diets

A feeding trial with 4 week-old goslings was conducted in 2003 using different proportions of chopped grass and grain pellets in the diet. Proportions of chopped grass and grain pellets in diets for Treatments 1, 2, 3 and 4 were 25:75; 50:50; 75:25 and 0:100, respectively. Weekly and final live weights of geese and the feather quality were measured. Treatments with higher grain contents produced higher live weights, and better feather quality.

The Role of Grasslands in the Diet of Geese

A feeding trial was conducted with 4 weeks old growing geese. Feeding treatments were different proportion of chopped grass and grain pellets. Daily DM intake, weekly live weight gains and final live weight was measured. It is concluded that 25% of chopped grass in the diet has similar result as only grain pellet diet. This is good for the economy of goose production.

Fate of Escherichia coli O157:H7 during Silage Fermentation

The survival characteristics of Escherichia coli O157:H7 in silage derived from contaminated grass were investigated. The survival of other enteric bacteria was also investigated to determine if E. coli O157:H7 demonstrates enhanced acid tolerance in comparison. Samples of chopped grass were treated as follows: (i) no additive (control); (ii) inoculation with E. coli O157:H7 to a final concentration of log10 4.0 CFU g−1; (iii) addition of an 85% solution of formic acid at 3.0 ml kg−1 grass; and (iv) addition of both E. coli O157:H7 and formic acid, at the above concentrations. Treated 6-kg grass samples were packed into laboratory silos, sealed, and stored at 15°C for up to 180 days. Individual replicate silos were removed from storage periodically and subjected to microbiological and chemical analyses. Chemical analyses of the silage samples indicated that lactic acid-dominant fermentations, with a rapid drop in pH, occurred. Numbers of enteric bacteria decreased from log10 7.0 to 8.0 CFU g−1 to undetectable levels within 19 days' storage. E. coli O157:H7 did not survive the silage fermentation process, with numbers declining from approximately log10 4.0 CFU g−1 to undetectable levels within 19 days of ensiling. The pattern of decline in numbers of E. coli O157:H7 was the same as that for the enteric bacteria, indicating that under the conditions tested, the acid tolerance of E. coli O157:H7 was not significantly different from the acid tolerance of other enteric bacteria. This study found that E. coli O157:H7 did not survive a good silage fermentation process, indicating that properly ensiled grass that is correctly stored is unlikely to be a vector for the transmission of the pathogen among cattle.