Luigi Stringi

Intake and milk production of goats grazing Sulla forage under different stocking rates

Abstract A total of 24 Girgentana goats was divided into 3 homogeneous groups grazing a sulla monoculture under stocking rate of 30, 50 or 70 goats/ha (LSR, MSR and HSR). Available biomass, herbage selected by goats and milk yield were measured and sampled. The DM intake of goats and its botanic composition and digestibility were assessed by the n-alkane method. Grazing at HSR was suspended 18 d before MSR and LSR (35 vs. 53 d), due to the low biomass availability. Over the first 35 d of grazing, the HSR reduced height and availability of herbage. The herbage intake and milk yield of goats increased from HSR to LSR, without relevant changes in milk quality. During all grazing period (53 d), the higher grazing pressure led to a lower total milk yield per goat, whereas the HSR produced the highest daily and total milk amount per ha.

Productivity of an Atriplex halimus shrubbery and effects of grazing on lambs

Abstract The objectives of this study were to 1) evaluate the productivity and forage quality of Atriplex halimus, 2) investigate modifications to shrub structure induced by grazing, and 3) assess live weight changes in lambs grazing on A. halimus with and without a feed supplement (wheat straw ± barley grain). The results showed that A. halimus had low productivity (approximately 1000 kg DM ha–1) but high tolerance to grazing by lambs, although minor modifications in plant structure due to grazing were observed. Lambs grazing A. halimus as a sole diet lost weight (about 60 g lamb−1 d–1; P < 0.01), probably as a consequence of the high salt content of the forage reducing both intake and digestibility. No significant benefits were obtained from the provision of wheat straw as an ad libitum supplement, possibly because the lambs were able to utilize understorey plants having a chemical composition similar to straw. Lambs supplemented with both wheat straw and barley grains (200 g lamb−1 d–1) had a significantly higher live weight (P < 0.01) than those grazing on A. halimus alone. The results suggest that a diet of A. halimus is not sufficient to maintain lamb live weight, and that supplementation with an energy source is necessary for lambs to gain weight.

Energy use efficiency of livestock farms in a mountain area of Sicily

Abstract The research aimed to evaluate the performance (in terms of energy) of livestock farms located in a Mediterranean mountain area and characterized by different stocking rates. Farm data were collected from in-person interviews of farmers of 58 farms representative of the livestock farms of the Madonie and Nebrodi mountains area (Sicily, Italy), including several parameters related to farm characteristics, animal, crop and pasture management. The farm parameters were used to calculate input and output energy values from which agroecosystem performance indicators were derived. Increasing stocking rate corresponded to a more than proportional increase in total inputs per unit area because of a greater farm dependence on external energy sources derived from agriculture (mainly for concentrate feed) and to a lower energy use efficiency. The indicator of dependence on non-renewable energy sources was, on average, very low irrespective of stocking rate. As stocking rate increased the farm autonomy indicator fell and the immediate removal indicator increased. Overall, the best agroecosystem performance in terms of energy was found on farms with lower stocking rates, higher proportions of permanent pastures to total farm area, and longer periods of exclusive grazing.

Technical Note: Comparison of Techniques for Evaluating the Relative Preference by Sheep Among Saltbush Clones

Abstract This research compared 4 field methods of evaluating the relative preference by sheep of 28 clones of saltbush (Atriplex halimus L.). The methods were as follows. 1) Leaf dots (LD): 8 leaves per shrub were marked on the lower surface with a small dot using a water-resistant, nontoxic ink. 2) Twig marks (TM): 2 current-year twigs per shrub were marked with 3 lines using the same ink approximately in the middle of the basal, median, and apical thirds. 3) Branch length (BL): 2 branches per shrub were marked with ink at the base of the current years growth. The twigs were measured from the marked point to the top, before and after sheep browsing. 4) Ocular estimation (OE): the percentage of the total number of current-year twigs browsed was visually estimated for each shrub. The percentage of use was calculated by counting the residual dots (LD) or marks (TM) after browsing and by calculating the difference between the 2 measures in the BL method. The trial was conducted in August and repeated in November and in both grazing periods 4 observations were made. Highly significant differences among clones were observed. The different methods generally gave similar results for the ranking of the clones, but each method showed a different discriminatory capacity. On the basis of the F ratio, the OE method seemed more efficient, although results were subjective and mainly dependent on the experience and skill of the observer. Among the methods based on the counting or measurement of markers, the discriminatory capacity decreased from LD to BL and TM, but the opposite order was observed for the ease of setting and counting the markers.