Comparative growth rates of various rumen bacteria in clarified rumen fluid from cows and sheep fed different diets.

Pure cultures of strains of different species of rumen bacteria were grown in filter-sterilized rumen fluid supplemented with glucose, bicarbonate, and reducing agent (cysteine and sulfide). Growth rates were determined in a series of experiments. Strains of species most abundant in the rumen grew more rapidly than strains of less abundant bacteria. Ammonia, amino acids, and peptides increased growth rates to some extent, but the greatest stimulatory effect for less abundant bacteria was provided by other factors, present in yeast extract. Factors released from lysates of mixed rumen microbes stimulated growth, but their rate of release was slow. It was concluded that, besides energy and nitrogen sources, growth factors of an as-yet-undetermined nature probably play an important role in determining the predominance of different bacterial species in the rumen.     

Comparative growth rates of various rumen bacteria in clarified rumen fluid from cows and sheep fed different diets.

Pure cultures of strains of different species of rumen bacteria were grown in filter-sterilized rumen fluid supplemented with glucose, bicarbonate, and reducing agent (cysteine and sulfide). Growth rates were determined in a series of experiments. Strains of species most abundant in the rumen grew more rapidly than strains of less abundant bacteria. Ammonia, amino acids, and peptides increased growth rates to some extent, but the greatest stimulatory effect for less abundant bacteria was provided by other factors, present in yeast extract. Factors released from lysates of mixed rumen microbes stimulated growth, but their rate of release was slow. It was concluded that, besides energy and nitrogen sources, growth factors of an as-yet-undetermined nature probably play an important role in determining the predominance of different bacterial species in the rumen.     

Grass maturity effects on cattle fed silage-based diets. 1. Organic matter digestion,rumen fermentation and nitrogen utilization

Four silages were harvested at approximately one-week intervals from the same timothymeadow fescue sward. Advanced maturity of the herbage was evidenced by increased neutral detergent fibre [409, 497, 579 and 623 g in 1 kg dry matter (DM)] and decreased nitrogen (N; 29.9, using four ruminally and duodenally cannulated young cattle in a 4 × 4 Latin square experiment. On DM basis (g kg⁻¹), the diet comprised grass silage (700), rolled barley (240) and rapeseed meal (60) and it was given at a rate of 70 g DM (kg live weight)^−0.75 per day.Organic matter digestibility decreased in a curvilinear manner (P_{LINEAR (L)} < 0.001, P_{CUBIC (C)} < 0.01) the values being 0.821, 0.816, 0.758 and 0.747 for the diets based on the four silages in the order of harvest date. Rumen pH increased linearly (P_L < 0.05) and ammonia N concentration decreased curvilinearly (P_L < 0.01, P_C < 0.05) as the grass matured. The molar proportion of acetate in the rumen VFA increased (P_L < 0.001) and the proportion of butyrate decreased (P_L < 0.001) with increased grass maturity. The silage harvest date did not affect the proportion of propionate. The changes in rumen fermentation pattern were associated with a decrease (P_L < 0.05) in rumen protozoal number with increasing maturity of grass.N intake decreased significantly (P_L < 0.001, P_C < 0.01) with the maturity of grass from 167.5 to 118.0 g per day, but duodenal non-ammonia N decreased only from 111.3 to 97.3 g per day indicating greater N losses from the rumen with early-cut silages. The efficiency of microbial protein synthesis in the rumen was not affected by the maturity of grass ensiled. Apparent digestibility of N decreased (P_L < 0.001, P_C < 0.01) and the degradability of N in the rumen decreased (P_L < 0.05) as the grass matured.     

Effect of low-roughage diets on the microflora and lipid metabolism in the rumen

Changing the diet of five lactating cows and one nonlactating cow from high to low roughage induced milk fat depression in the lactating cows and altered the composition of the rumen microflora. While the numbers of lactic and propionic acid-producing bacteria increased, the numbers of Butyrivibrio spp. decreased. The numbers of lipolytic bacteria and the in vitro lipolytic activity of the rumen fluid were also decreased, as was the extent of hydrogenation of linoleic and linolenic acids combined in soybean oil incubated in vitro with rumen fluid. It is suggested that among the bacterial population in the rumen the vibrios, which were adversely affected by the low-roughage diets, may contribute significantly to both lipolysis and hydrogenation in the rumen.     

Effect of feeding complete diets containing graded levels of Prosopis cineraria leaves on feed intake,nutrient utilization and rumen fermentation in lambs and kids

A study was conducted to assess the effect of feeding graded levels of tannin-containing Prosopis cineraria leaves in a complete feed mixture (CFM) on the performance of lambs and kids. Eighteen lambs and 18 kids of Malpura and Marwari breed, respectively of similar age (90 days) and body weight (11.0 kg), were randomly distributed in to three groups of six each. Each group was offered complete feed mixtures ad libitum in feeding troughs under group feeding system for 90 days. The concentrate component of CFM was from the commercial feed in mash form containing corn, soybean meal, wheat bran and de-oiled rice bran. Prosopis leaves were ground to pass through a 4 mm sieve before being thoroughly mixed with required quantity of concentrate mash. CFMs contained graded levels of P. cineraria leaves. In, CFM-1, ratio of P. cineraria to concentrate mixture was 25: 75 (T₁), whereas in CFM-2 and CFM-3, it was 50:50 (T₂) and 75:25 (T₃), respectively. The lambs in L₁, L₂ and L₃ and kids in K₁, K₂ and K₃, groups received CFM-1, CFM-2 and CFM-3, respectively. CP (g kg⁻¹) was 182 in CFM-1, 162 in CFM-2 and 140 in CFM-3. P. cineraria leaves contained (g kg⁻¹) CP 159, neutral detergent fibre (NDF) 567, acid detergent fibre (ADF) 360 and acid detergent lignin (ADL) 189 on dry matter (DM) basis. The extractable condensed tannin (CT; leucocyanidin equivalent), hydrolysable tannin (HT) and protein precipitation capacity (PPC) of the leaves (g kg⁻¹) were 90.7, 3.4 and 111.5, respectively. DMI in L₁ and L₂ lambs were higher than their corresponding groups in kids, whereas it was reverse in L₃ (more in kids than lambs). Significant difference in digestible crude protein (DCP) intake was recorded among the groups in both lambs and kids. In lambs, highest DCPI (g day⁻¹) was recorded in L₁ (93.3), as compared to L₂ (82.2) and L₃ (37.2), whereas in kids it was K₂ (73.4), followed by K₁ (69.2) and K₃ (43.8). Significant difference in the digestibility of DM, CP and NDF were recorded among three groups in both species. Maximum nutrient digestibility was recorded in T₁ followed by T2 and T₃ in both lambs and kids. However, digestibility of all the nutrients was more in kids than that of lambs. Maximum ammonia-N, total N and trichloro acetic acid (TCA) precipitable N was recorded in T₁ followed by T₂ and T₃ in both the species. However, there was no typical trend between the two species in rumen parameters. Blood haemoglobin (Hb) and blood urea nitrogen (BUN) values were highest in T₁ followed by T₂ and T₃ in both lambs and kids. After 90 days of intensive feeding, maximum weight gain was recorded in T₂ as compared to that of T₁ and T₃ in both lambs and kids. Although L₁ lambs performed better under high concentrate diet compared to K₁ kids, weight gain in K₂ and K₃ kids were significantly higher compared to their counter part lambs. Similar was the trend in ADG also. It was concluded that performance of lambs and kids differed with the level of CT in their diet and kids performed better on high tannin diet as compared to that of lambs.     

The effect of rumen ciliates on chitinolytic activity,chitin content and the number of fungal zoospores in the rumen fluid of sheep

The objective of this study was to investigate the effect of selected protozoa on the degradation and concentration of chitin and the numbers of fungal zoospores in the rumen fluid of sheep. Three adult ewes were fed a hay-concentrate diet, defaunated, then monofaunated with Entodinium caudatum or Diploplastron affine alone and refaunated with natural rumen fauna. The average density of the protozoa population varied from 6.1 · 10⁴ (D. affine) to 42.2 · 10⁴ cells/ml rumen fluid (natural rumen fauna). The inoculation of protozoa in the rumen of defaunated sheep increased the total activity of chitinolytic enzymes from 2.9 to 3.6 μmol N-acetylglucosamine/g dry matter (DM) of rumen fluid per min, the chitin concentration from 6.3 to 7.2 mg/g DM of rumen fluid and the number of fungal zoospores from 8.1 to 10.9 · 10⁵ cells/ml rumen fluid. All examined indices showed diurnal variations. Ciliate population density was highest immediately prior to feeding and lowest at 4 h thereafter. The opposite effects were observed for the numbers of fungal zoospores, the chitin concentration and chitinolytic activity. Furthermore, it was found that chitin from zoospores may account for up to 95% of total microbial chitin in the rumen fluid of sheep. In summary, the examined ciliate species showed the ability of chitin degradation as well as a positive influence on the development of the ruminal fungal population.     

Effect of various chloride salts on the utilization of phosphorus, calcium, and magnesium

Only part of the effect of dietary protein on urinary calcium excretion can be ascribed to sulfur amino acids. We hypothesized that chloride, another factor often associated with isolated proteins, and another amino acid, lysine, affect utilization of calcium. The effects of supplemental dietary chloride, inorganic or organic, on calcium, phosphorus, and magnesium utilization were studied in two rat studies. Weanling Sprague-Dawley rats were fed semi-purified diets that contained moderate (1.8 mg Cl/g diet) or supplemental (15.5 mg Cl/g diet) chloride as sodium chloride, potassium chloride, or lysine monohydrochloride with or without calcium carbonate for 56 or 119 days. Rats fed supplemental sodium chloride or potassium chloride had higher urinary phosphorus excretion, more efficient phosphorus absorption, but unchanged tissue phosphorus levels after 7 and 16 weeks of dietary treatment as compared to rats fed moderate chloride. Rats fed supplemental sodium chloride or potassium chloride excreted more calcium in urine at 7 weeks and absorbed calcium less efficiently at 16 weeks. Tissue calcium concentrations were unaffected, but total tibia magnesium and plasma magnesium concentrations were lower in rats fed supplemental sodium chloride or potassium chloride than those fed moderate chloride. Lysine chloride with or without additional calcium elevated urinary calcium excretion even more than sodium chloride and potassium chloride ingestion. Rats fed lysine chloride with supplemental calcium had smaller apparent absorption and urinary losses of phosphorus and magnesium after 16 weeks and lower tibia and plasma magnesium concentrations than rats fed lysine chloride.     

Effect of the rumen ciliates Entodinium caudatum, Epidinium ecaudatum and Eudiplodinium maggii, and combinations thereof, on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 x 2 x 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH4-to-CO2 ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.     

Effect of the rumen ciliates Entodinium caudatum,Epidinium ecaudatum and Eudiplodinium maggii,and combinations thereof,on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 × 2 × 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH₄-to-CO₂ ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.