Growth Performance and Plasma Metabolites of Grazing Beef Cattle Backgrounded on Buffel or Buffel-Desmanthus Mixed Pastures

Dietary crude protein and dry matter digestibility are among the major factors limiting feed intake and weight gain of cattle grazing native and improved pastures in the subtropics of Northern Australia during the dry season. Incorporating a suitable legume into grasses improves pasture quality and cattle weight gain, but only a limited number of legume pastures can establish and persist in cracking clay soils. This study aimed to evaluate the effect of Desmanthus inclusion in buffel grass (Cenchrus ciliaris) pastures on the plasma metabolite profile and growth performance of grazing beef cattle during the dry season. We hypothesised that backgrounding steers on buffel grass-Desmanthus mixed pastures would elicit significant changes in plasma glucose, bilirubin, creatinine, non-esterified fatty acids and β-hydroxybutyrate, resulting in higher liveweight gains than in steers on buffel grass only pastures. Four hundred tropical composite steers were assigned to buffel grass only (n = 200) or buffel grass oversown with Desmanthus (11.5% initial sward dry matter) pastures (n = 200) and grazed for 147 days during the dry season. Desmanthus accounted for 6.2% sward dry matter at the end of grazing period. Plasma metabolites results showed that changes in β-hydroxybutyrate, creatinine, bilirubin, glucose and non-esterified fatty acids were within the expected normal range for all the steers, indicating that with or without Desmanthus inclusion in the diet of grazing steers, animal health status was not compromised. It was also evident that Desmanthus inclusion in buffel grass pastures had no impact on the plasma metabolite profile, liveweight and daily weight gain of grazing steers. Therefore, our tested hypothesis of higher changes in plasma metabolite profile and higher liveweight gains due to backgrounding on low-level buffel grass-Desmanthus mixed pastures does not hold.

Ruminal and Intestinal Morphometric Parameters of Lambs Fed Diets Containing Mimosa Tenuiflora (Willd.) Hay Replacing Buffel Grass Hay

The objective in this study was to evaluate morphometric parameters of the ruminal papillae and intestinal villi of lambs fed diets containing Mimosa tenuiflora (Willd.) hay replacing Buffel grass (Cenchrus ciliaris L.) hay. Twenty-eight Santa Inês lambs with initial body weight of 20.3 ± 1.49 kg were used, being distributed in a completely randomized design with four treatments (0, 333, 670 and 1000 g/kg DM). The width of the ruminal papillae was not affected (P > 0.05), while their area linearly decreased (P = 0.01) as the level of M. tenuiflora hay increased. In the duodenum, the height (P < 0.0001) and the surface (P = 0.01) of the villi linearly decreased with the increase in the level of M. tenuiflora, while the width (P = 0.0001) and the area (P = 0.03) quadratically decreased with minimum values of 132.95 and 50,625.53 µm at the levels of 436 and 575 g/kg, respectively. There was a quadratic increase in the height of the jejunum villi (P < 0.0001) with a maximum value of 623.22 µm at the level of 333 g/kg, while the width quadratically decreased with a minimum value of 143.33 µm at the level of 526 g/kg and the area linearly decreased (P = 0.02). The height of the ileum villi (P = 0.0003) as well as the depth of the crypts in all segments (P < 0.001) linearly decreased. Therefore, it is suggested the substitution of C. ciliaris hay by M. tenuiflora hay up to 333 g/kg DM.

Goats fed with non-protein nitrogen: ruminal bacterial community and ruminal fermentation, intake, digestibility and nitrogen balance

The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P < 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P < 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.

Effect of different periods of irrigation on growth and yield of Cenchrus ciliaris at semi-arid zone of North Darfur State, Sudan

Buffel grass Cenchrus ciliaris L. (Poaceae) is recognized as one of Australia's most serious environmental weeds. This introduced grass has been associated with loss of native species and alteration of fire regimes. However, it is also highly valued as a pasture species for arid and semi-arid zones and its weed status is highly controversial. This study was conducted at the private farm, Southern part of Alfashir Airport, North Darfur State, Sudan. The objective was to evaluate the effect of different periods of irrigation (DPI) on growth and forage yield of Cenchrus ciliaris during years of 2018 and 2019. The experiment was laid-out in a randomized complete block design (RCBD) with four replicates, the plot size was 8x5 m. Data collected included plant density, plant ground cover, plant height and dry matter yield. DPI showed significant effect on plant density, plant ground cover, Plant height and dry matter yield. The study showed that irrigation every 7 days (Ir1) was suitable for buffel grass at semi-arid zone in Sudan. Quantitative studies are needed to determine its ecological effects.

Substitution of Non-Protein Nitrogen for True Protein Increases Microbial Growth and Degradation of Fibrous Carbohydrates from Buffel Grass

The aim of this study was to evaluate the effects of different sources of nitrogenous compounds on the in vitro utilisation of neutral detergent fibre from buffel grass in advanced phenological stage, the experiment consisted of testing five levels of substitution of urea for casein: 0, 25, 50, 75 and 100%. The effects of the substitution levels were evaluated by in vitro incubation at different times: 0, 3, 6, 9, 12, 24, 36, 48, 72 and 96 h. The degradation rate of potentially degradable NDF increased up to the replacement level of 50%, but declined by 6.53 and 13.57% in the treatments with 75 and 100% substitution of urea for casein, respectively, as compared with the treatment without substitution. Discrete lag time was reduced by 1.31 h in the treatment with 50% substitution and by 2.7 h at 100% substitution, as compared with 0% substitution. The substitution of up to 50% non-protein nitrogen for true protein increased microbial growth efficiency by 16.1% as compared with the treatment without substitution. Acetate and propionate concentrations were not affected by the substitution of urea for casein. The use of 50% non-protein nitrogen and 50% true protein as nitrogen sources for rumen microorganisms favour microbial growth and optimise the degradation of neutral detergent fibre from low-protein buffel grass. © 2021 Friends Science Publishers

Molecular approaches for identification of the apomictic/sexual reproductive mechanism and genetic variability in buffel grass (Cenchrus spp.) accessions

Cenchrus spp. encompasses forage grasses that are especially important for drylands. Thus, information on their reproductive mechanism and genetic diversity is needed. The Active Germplasm Bank (AGB) of the Embrapa Semi?rido (Tropical semiarid research center) has 115 accessions of Cenchrus spp. that were not molecularly characterized. Therefore, the objective of this work was to evaluate the genetic diversity of Cenchrus spp. accessions in the AGB, and identify their reproductive mechanisms using DNA markers. Specific SCAR markers Q8H, UGT197, and PCAB10, in addition to the SCAR marker 4HS