The effect of concentrate inclusion level on the dose constant (kl), for each of the four different basal roughage rations fed. The effect of lusem inclusion level on the rate constant (k 1), for each of the four different concentrate levels fed.
Quality attributes of feeds
- Apparent versus true digestibility of nutrients
- Feed intake
- Factors affecting intake
- Animal factors
- Food factors
It has been shown that the size of the animal plays an important role in the regulation of feed intake. The speed at which feed particles are broken down in the rumen can be directly attributed to certain aspects of the feed itself.
Clearance of ingested feed material from the rumen
The microbial digestion of ingested feed material
Particulate passage rate: Those particles that escape the rumen leave in aqueous suspension (Sutherland, 1988). The rate of hydration and specific gravity also affect the rate of passage of particles from the rumen (Van Soest, 1994).
Stratification or entrapment of particles in the fibrous mat of rumen ingesta
The proportion of particles that leave or re-enter the rumen after re-ingestion of the ruminal bolus depends on their density. Oscillatory contraction and relaxation of the cranial ventral sac and reticulum eventually propel the particles into the reticulum.
Abstract
More importantly, however, supplementary feeding strategies can only be effective if the deficits of the feed are related to the requirements of the animal (Cronje, 1990). The slowly degradable fraction is available for degradation by rumen microbes, although the extent of degradation depends on the time spent in the rumen. 1989) noted that, when formulating ruminant feeds, it is important to know what proportion of the protein fed to the animal is ungraded dietary protein that can be digested in the lower digestive tract of the animal and what proportion of the dietary protein rumen is. degradable The undegraded dietary protein will act as a supplement to the amino acids of microbial origin and thereby contribute to meeting the amino acid requirements of the tissues (Henning et al., 1989).
Rooke (1985) proposed a method that could be used to determine the digestibility of the RUP fraction. To do this, two assumptions must be made, namely (a) postruminal protein digestion occurs in the same manner as protein digestion in the chicken digestive tract and (b) potentially RDP and RUP undergo the same magnitude. digestion in the small intestine of the chicken. 1989) proposed a method for determining RUP digestibility using roosters. The bags were tied to a circular stainless steel disc (100 g, 6 cm diameter, 4 mm thickness) with 10 evenly spaced small holes drilled around the outside of the disc.
For each incubation period, one bag per sample was placed in the rumen of each of the three cows. After completion of the incubation period, the bags were removed and rinsed under tap water until the water was clear. The effective degradability of the protein sources depends on the speed at which the feed passes through the rumen.
Results
Assuming that the soluble portion of the supplement degrades during passage, it is possible to estimate the effective degradability of the supplement using a suitable estimate of passage rate. Due to the differential passage rate for both particles and liquid through the rumen of sheep, beef and dairy cattle, the effective DM and nitrogen degradability varied significantly, although the same trends were shown. The effective degradability of a supplement is an indication of the amount of protein available for microbial digestion in the rumen.
Thus, accurate estimation of the RDP fraction, as well as the RUP fraction, is essential when formulating diets for ruminants. This protein would not be available for digestion by the chicken, reducing the estimated digestibility of the protein for the ruminant animal. For example, if certain proteins are highly degradable in the rumen, while others are highly degradable in the rumen, this difference, due to structural differences between the proteins themselves, may be reflected in the digestibility of the protein in the rumen. gastrointestinal tract of the chicken.
The five diets formulated by Henning et al. 1989) varied in UDP and each contained one of the protein-rich feeds: sunflower oil cake, cottonseed oil cake, corn gluten meal and fish meal. Evaluation of supplements as part of a complete ration can be problematic because variation in ration composition will affect the degradability of the supplement as the rumen microbial ecosystem adapts to different conditions. The digestible RUP was calculated as the difference between the digestibility of real protein (in roosters) and the effective degradability of protein in the rumen.
Abstract
They further found that most of the large particles that break down in the rumen are produced as a result of ruminal chewing. This large difference in animal size was purposely intended to determine whether animal body weight affected the rate of particle outflow from the rumen. At the same time, the DM, CF, NDF and fat content of the diets decreased when the proportion of lucema in the diet increased.
The effect of diet on CP intake was highly significant (P<0.001) with a linear increase of 2.450 g/day per unit increase in dietary lucem content. Crude fiber and NDF intake increased by 1.2 g/day and 2.4 kg/day respectively per unit increase in the lucem content of the diet. This method would provide a better picture of the movement of particles representative of the complete ration from the rumen.
Another compositional factor related to feed intake may also play a role in particle passage rate. As the NDF portion of the diet is reduced, rumination decreases, allowing for an increased fibrous raft in the rumen. While feeding activities were monitored, intake increased significantly as alfalfa content in the diet increased.
Abstract
The effect of increasing basal ballast feed quality and level of concentrate addition on basal ballast feed intake and rumen particle transit rate (kl) of South African Merino sheep was investigated. Four qualities of ballast forage were achieved by supplementing the base forage (poor quality hay) with different amounts of lucema hay, so that lucema contributed 80%. Sixty-four sheep were blocked by weight and sex and randomly assigned to one of 16 treatments in a completely randomized block.
The relationship between level of concentrate supplementation on kl is inverse quadratic and significant (P<0.05). Alfalfa inclusion level had no effect on kl, but the effect of concentrate supplementation level on total dry matter intake (DMI) and total crude protein (CP) intake was highly significant (P<0.001) with DMI and CP intake quadratically increased as the level of feedstock supplementation increased. NDF intake decreased quadratically (P<0.05) as alfalfa inclusion level increased, while CP intake increased quadratically (P <0.001) as alfalfa inclusion level increased.
These results indicate that below a certain level the effect of concentrate supplementation on fiber digestibility is not severe and that forage and NDF intakes are not affected.
Introduction
This effect is probably a consequence of the greater potential intake of high-quality forage, with the animal reducing intake of the latter to maintain a similar intake of nutrients (Jarrige et al., 1996). This study was designed to investigate the effect of supplementing a basal forage (of varying quality) with an easily digestible carbohydrate and nitrogen source. The effect on feed intake and the passage rate of digestion from the rumen was investigated.
Materials and methods
After a 14-day adaptation period, each animal was fed 10 g of ground feed (particle size > 1 < 1.2 mm) before consuming the daily feed intake. Collection of stool samples began 48 hours after caustic administration, with further rectal collections from the rectum after and 120 hours after dosing. Collected faeces were dried, ground and stored until chromium analysis as described in Chapter Three.
Intake studies: The amount (by weight) of roughage offered to each sheep over the period of faecal collection was recorded and any residual feed remaining at the end of the collection period was reweighed to determine mean daily intake by difference. Laboratory analysis: DM, OM, nitrogen, fat (ether extract), CF and NDF were analyzed as described in Chapter Three. Faecal samples for the determination of particulate passage rate were analyzed for chromium according to the method described by Costigan and Ellis (1987) as described in Chapter Three.
Data derivation and statistical analysis
Results
The least squares means (LSmeans) of passage rate, for each treatment, were plotted using a spreadsheet package, Microsoft Excel (Microsoft Corporation, . 1997). DM and CP intake derived from both forage and concentrate supplements for each of the 16 treatments.
Discussion
The degree of digestion of the degradable fractions depends on the balance between the rate of degradation of the ingested material and the rate at which it leaves the rumen (Tamminga, 1993). Thus, as discussed in Chapter One, any factor that increases the rate at which particles are removed from the rumen will have a positive effect on the animal's overall feed intake. The nutrient composition of the concentrate and the rumen degradability of the protein source used in the concentrate ration give rise to some discussion.
Of considerable importance in determining the effect of a supplement on the rumen microbial population is the degradation pattern of the supplement itself and it is essential that this aspect is not overlooked. Once the degradation characteristics of the supplement are known, an assessment of its effect on the rumen microbial population can be made. A change in the quality and/or composition of the basal raw materials will have an effect on the size and composition of the rumen microbial population, with a subsequent effect on the degradability and rate of passage of any supplement provided.
In Chapter Two, the effect of the animal species on the effective degradability of the supplement as a result of the retention time is noted. There is a significant effect of the estimated passage rate on the effective dry matter and protein degradability of supplements, as illustrated by the estimated ED for the different species. Changes in some physical features of digestion in the reticulo-rumen of cows fed once daily.
A note on the use of chicken to predict protein digestibility in the small intestine of sheep. A study of the synthetic fiber bag technique for determining forage digestibility in the rumen.
