S. Fernández-Rivera

Effect of timing and duration of grazing of growing cattle in the West African Sahel on diet selection, faecal output, eating time, forage intake and live-weight changes and nutrition and performance of cattle

Sixty-four Azawak male weaned calves were allotted to eight treatments (T) in two trials to study the effect of timing (day or day-and-night) and duration of grazing on diet selection, faecal output, eating time, forage intake and weight changes. Grazing time during the day was 6 h for T 1, 2 and 3; 9 h for T 4, 5 and 6; and 12 h for T 7 and 8. Night grazing time was 0 h for T 1, 4 and 7; 3 h for T 2, 5 and 8; and 6 h for T 3 and 6. The trials were conducted from July 1995 to May 1996 covering the wet (WS), early dry (EDS) and late dry (LDS) seasons. Eight oesophageally fistulated steers were used in a cross-over design to sample the diet selected by day-grazers (D1) and by day-and-night-grazers during the day (D2) and at night (N2). Forage intake was determined from individual data on faecal output from all the calves and means of in vitro organic matter digestibility of extrusa of the fistulated steers. Water intake and eating time were measured in LDS. In WS there were no differences (P > 0?05) in the quality of the diet (extrusa) selected for D1, D2 and N2. In LDS, crude protein content for D1 was lower than for D2 (73 v. 79 (s.e. 2) g/kg dry matter, P < 0?05). In all seasons, faecal output and forage intake increased with total duration of grazing. Total time spent eating increased linearly with increasing total time allowed for grazing. These results suggest that allowing additional grazing time during the night leads to increased forage intake and consequently provides an opportunity for better animal production, especially in the dry season

Approaches to improve the utilization of food-feed crops—synthesis

Abstract This paper synthesizes the key findings presented in the previous 15 papers, and presents a summary of a discussion on best approaches, strategies and partnerships to improve the utilization of food–feed crops. The synthesis provides guidance for future research and development in crop–livestock systems in developing countries. It also stresses the need for greater integration, focus, coordination of efforts to improve the utilization of food–feed crops, if the benefits from advances in research and output delivery are to reach the hundreds of millions of resource-poor livestock keepers in developing countries.

Soil Fertility Maintenance and Food Crop Production in Semi-Arid West Africa: Is Reliance on Manure a Sustainable Strategy?

Animal manure is of vital importance in maintaining soil fertility in semiarid west Africa due to the low level of use of inorganic fertilizer. Using data from Niger however, it is shown that insufficient animals are available to provide the manure needed to sustain crop yields on a long-term basis. The limitations posed by animal numbers and feed availability imply that with the increasing intensity of land use in Niger and other countries In the region, manure alone will not provide the key to attaining sustainable yield levels. External Inputs in the form of inorganic fertilizers are needed. However, the gap between present fertilizer use and the required level is wide. To ensure the availability and increased use of fertilizers at the farm level, appropriate public policies are needed to ease the constraints that have inhibited the widespread use of fertilizers in semiarid west Africa.

The effect of supplementing maize stover with cowpea ( Vigna unguiculata ) haulms on the intake and growth performance of Ethiopian sheep

This study compared the effect of supplementing maize stover (MS) with cowpea (Vigna unguiculata) haulms or commercial concentrate (CC) on feed intake, nutrient digestibility, live weight gain and carcass yield of male Ethiopian Highland sheep. Two cowpea genotypes, 12688 (forage) and IT96D-774 (dual-purpose), were used. A randomised block design was applied with groups of eight sheep, blocked by weight, allocated to one of six treatments; MS ad libitum either unsupplemented or supplemented daily with 150 or 300 g dry matter (DM) of either cowpea or CC. MS contained more neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin than either cowpeas or CC. Crude protein (CP) content of the forage-type cowpeas was higher than either dual-purpose or CC, while MS had the lowest CP content. Relative to the negative control group, cowpea at either level significantly (P < 0.01) increased both MS intake and total NDF and lignin. Supplementation significantly (P < 0.01) increased nitrogen (N) intakes relative to the negative control, with N intake for CC and dual-purpose cowpea (high level) being similar to the intakes for cowpeas at 150 g. N intake with the forage-type cowpea offered at higher levels was significantly (P < 0.01) greater than the other groups. No significant differences (P > 0.01) in MS intake were identified between cowpeas at either level or CC and, although intake level of CC increased, it did not differ significantly from the negative control group. Supplementation significantly (P < 0.01) improved average daily gain, with the negative control group losing weight over the experimental period, and increased final live weight, carcass cold weight and dressing percentage. Supplementation significantly improved the apparent digestibility of DM, organic matter and NDF, with no significant difference found between cowpeas at either level. N retention was negative for sheep offered only MS, but positive with all supplements, with cowpeas improving N retention to a greater extent than CC. Interestingly, N retention/N intake was higher with cowpeas offered at the lower level suggesting an improvement in utilisation efficiency. The results indicate that the supplementation of MS with cowpea enhanced ruminant production through improvements in digestibility and intake. Further, as production improvements associated with the two levels of supplementation did not differ significantly, it is suggested that where limited quantities of cowpea are available, it may be of greater nutritional benefit to offer smaller quantities over an increased number of animal days.

Effect of nocturnal grazing and supplementation on diet selection, eating time, forage intake and weight changes of cattle

Sixty-four Azawak male calves were used to study the effect of nocturnal grazing (NG) and supplementation (S) in the dry season on forage and water intake, faecal output, eating time and weight changes of cattle in the Sahel. Treatments were factorial combinations of four levels of NG (0, 2, 4 and 6 h/day) and two levels of S (0 and 608 g dry matter (DM) per animal per day). All animals were allowed to graze 10 h during the day and were weighed every 2 weeks during the 70-day experimental period. Eight oesophageally fistulated steers were used in a cross-over design to sample the diet (forage) selected during the day and at night by supplemented and non-supplemented animals. Extrusa crude protein and in vitro organic matter digestibility were not influenced by supplementation ( P > 0·05). Time spent eating during the day or at night were not affected by supplementation but total eating time increased by 39·4 (s.e. 2·1) min/h of NG. Forage intake increased with increase in NG, while total food intake (forage + supplement) increased with supplementation (82·4 v. 92·1 (s.e. 2·4) g DM per kg M 0·75 per day). The supplemented animals also drank more water than the non-supplemented (26·2 v. 24·8 l per animal per day). Average live-weight change (LWC) increased by 24·4 (s.e. 8·7) and 9·3 (s.e. 6·2) g/h of NG in non-supplemented and supplemented animals, respectively. Supplementation improved LWC (‐107 v. 99 g/day, s.e. 14, P < 0·05). Night grazing improves dry season performance and its effect decreases when cattle are supplemented.

The Effect of Supplementation with Fresh Browse of Ziziphus mauritiana or Combretum aculeatum on Feed Intake, Nitrogen Utilization and Growth of Grazing Range Sheep

The influence of 0, 60 or 120 min access to a grove of either Ziziphus mauritiana (Ziziphus) or Combretum aculeatum (Combretum) on forage intake and on the digestibility, growth and excretion of nutrients was determined using 40 Oudah rams grazing for 7 h/day on poor-quality dry season pasture in the Sahel. The effects of browse species and browsing duration (0, 30, 60 or 120 min) on the ruminal ammonia content were also evaluated using 8 mature fistulated rams. Ziziphus increased both total digestible organic matter and total dry matter intakes per (kg live weight)0.75 without decreasing herbage intake, whereas 60 or 120 min access to Combretum reduced herbage intake by 6.3% and 4.2%, respectively. The digestibility of the diet decreased (p<0.05) with the duration of access to the groves. Despite the provision of more nitrogen (N) than in the control diet, ruminal NH3-N decreased 24 h after browsing commenced. The reduced live weight gain of sheep browsing Combretum may indicate more deleterious compounds in Combretum than in Ziziphus. Ziziphus appears to have more potential than Combretum to increase sheep production in low-input crop/livestock systems.

Influence of dry season supplementation for cattle on soil fertility and millet (Pennisetum glaucum L.) yield in a mixed crop/livestock production system of the Sahel

An experiment was conducted in 1996 and 1997 in semi-arid Niger, to determine the influence of supplementation (no supplement, supplemented with millet bran + simple superphosphate + blood meal) of cattle and mulching (0 or 3 t ha−1 of Aristida sieberiana straw) on soil fertility and millet yield. Manure was applied through corralling at a rate of 3 t faecal dry matter (FDM) ha−1 alone or associated to mulching. The residual effects of the treatments were measured on a second millet crop in 1997. Compared to control, the association of mulching and corralling of supplemented as well as non supplemented cattle increased soil pH (KCl) (P < 0.01), Bray1-P (P < 0.05) and NH4-N (P < 0.05); grain by 136% (P < 0.01) stover yeild by moer than 150% (P < 0.05); and N and P uptake (P < 0.01) during the two cropping seasons. The association of mulching and corralling increased soil NH4-N (P < 0.01) and soil pH (P < 0.01), compared to the sole corralling. The improvement of soil chemical properties resulted in grain yield increases of 54% (P < 0.01) and stover increases of 42% (P < 0.01). The effect of mulching and corralling association on grain and stover yeilds was higher when cattle were supplemented (67 and 50%) than when they were not supplemented (30 and 26%). The effects of the supplementation on grain and stover yields, and N and P uptake by millet, were restricted, when animals were corralled on bare soil (no mulching). The residual effects of supplementation were minimal.

Effect of type and level of roughage offered to sheep and urine addition on compost quality and millet growth and production in the Sahel

A greenhouse trial was carried out at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), at Sadoré (13°15′ N, 2°18′ E), Niger. Experiments were conducted in conjunction with a feeding trial. The feeding trial yielded eight types of compost made from faeces and leftovers with or without urine addition from sheep fed either bush straw or millet stover offered at 60 or 80 g dry matter (DM) kg−1 live weight (LW). In the second trial the agronomic value of composts to a millet crop was evaluated. The level of roughage on offer did not affect compost quality. Urine addition increased N content in composts (P<0.05), but had no effect on P. Millet stover based composts contained 24% more N and 42.5% more P than composts made with bush straw (P<0.05). Urine addition enhanced millet growth between 15 and 60 days after planting (DAP), increased millet aboveground mass by a factor 2.8, and increased the efficiency of N and P use by 100% and 50%, respectively. Millet response (growth, phytomass, N and P uptake, apparent efficiency of N and P use) to urine addition was higher with millet stover based composts than with bush straw based composts (P<0.05). It was concluded that addition of urine during composting of roughage leftovers and faeces from stall-fed animals could significantly improve nutrient recycling and consequently the productivity of mixed farming systems of semi-arid West Africa.

Collecting, Processing and Storage of Plant Materials for Nutritional Analysis

A solid sampling strategy for plant material is the first step in screening forages for nutritional analysis and extra-nutritional attributes to determine if potential forage species, with good adaptation and biomass production are suitable for use as livestock feeds. Since the morphological phenotype is rarely a good indicator of nutritional traits, nutritional analysis is essential when selecting plants as feeds. It is not possible to select forages based solely on biomass production without taking into account the nutritional and anti-nutritional attributes. Some species with leafy and high productivity may contain plant secondary metabolites that may be toxic and make them unsuitable for use as feeds. A good example of this is Leucaena, which is fast growing and yields up to 15 tons/ha of forage dry matter per year, but because of the mimosine in the leaves could initially only be fed in quantities up to 30% of the diet without causing toxicity symptoms. This was not apparent from looking at the plant and emphasizes the need to do a thorough nutritional evaluation before introducing new species as livestock feeds. However, identification of mimosine degrading rumen microbes now allows livestock to consume larger quantities [5] and makes this both a productive and nutritionally useful forage plant in many tropical livestock systems.

Nutrient Management in Livestock Systems in West Africa Sahel with Emphasis on Feed and Grazing Management

Feed and grazing management affect both the quantity and quality of animal manure and consequently nutrient cycling in the mixed crop-livestock systems in West Africa Sahel. Dietary measures can significantly influence the composition of manure and hence it’s agricultural value. High nutrient feed will generally result in higher nutrient content of the manure whereas a decline in feed quality will generally lead to increase in the indigestible fractions in the feeds. Apart from feed and feeding practices, grazing management also affects the amount and nutrient contents of manure that can be recycled to the cropland. When animals are used to deposit manure in the crop field, conflicts often arise between the need for animals to graze long enough for adequate feed intake and the need to collect manure. This paper examines the effects of feed and grazing management on livestock-mediated nutrient transfers in mixed crop-livestock systems in West Africa Sahel. Results from grazing trials in Niger showed that nitrogen voided in faeces follow the trend of nitrogen contents in the feed for grazing cattle. Animals that had additional grazing time in the night consistently had higher forage intake and consequently, higher average daily gain than those that grazed only during the day in all seasons. However, additional grazing at night reduced the amount of manure that could be collected for crop fields unless the grazing location is crop field. It is therefore necessary to optimize the animals’ time for foraging to maintain or increase livestock output in terms of meat and/or milk, and for manuring to sustain soil fertility and hence crop production.