Utilisation de l’habitat et pressions anthropiques sur une population de rorquals à bosse (Megaptera novaeangliae) de Guadeloupe par suivi terrestre

Le sanctuaire Agoa est une aire marine protégée dans la zone économique exclusive (ZEE) des Antilles françaises qui fut créée en 2010 pour la conservation des mammifères marins et de leurs habitats. Il est connu que le rorqual à bosse fréquente les eaux des Antilles de décembre à mai pour la reproduction et la mise bas. Par contre, peu d’information existe sur l’abondance, le comportement, la distribution et les pressions anthropiques sur cette espèce aux Antilles et encore moins dans le sanctuaire. Cette maîtrise s’intéresse principalement à connaître cette espèce dans un secteur précis de cette aire marine et les liens qu’elle entretient avec certains utilisateurs humains de son habitat. Le tout vise à informer les intervenants en place, autant institutionnels qu’utilisateurs, vers une mise en place de mesures de conservation adaptées. Un suivi terrestre hivernal de plus de 300 heures, en 2012 et 2013, a permis de déterminer l’utilisation de l’habitat et les pressions anthropiques sur une population de rorquals à bosse fréquentant le sud de la péninsule de la Pointe-des-Châteaux en Guadeloupe. Il s’agit du premier suivi terrestre de cette espèce aux Antilles françaises et un des premiers dans l'arc caribéen. La zone d’étude couvre environ 264 km2 et serait une des zones les plus fréquentées de l’archipel guadeloupéen par l’espèce. À l’aide d’un théodolite, la trajectoire de 107 groupes différents (137,8 heures, 699 remontées) a été décrite. Les résultats montrent que la zone d’étude est principalement fréquentée en mars et avril, avec une abondance maximale au début du mois d’avril. La forte présence de baleineaux, particulièrement au mois de mars, pousse à croire que cette zone est utilisée comme pouponnière. Le comportement n’est pas aléatoire dans la zone d’étude et les trajectoires convergent vers certaines zones ayant possiblement un lien avec la bathymétrie. De plus, la zone marine à proximité de la Pointe-des-Châteaux pourrait potentiellement être un lieu de convergence des groupes. Ceux-ci se déplacent à vitesse réduite en direction ENE en général, à l’exception des femelles accompagnées de baleineaux qui prennent une orientation tout autre, c’est-à-dire vers le ONO, et ce à plus grande vitesse. Bien que la pression d’observation soit considérée comme modérée, une forte proportion des remontées se trouve dans les corridors de navigation présents dans la zone d’étude. De plus, le corridor de navigation des navettes entre Saint-François et La Désirade comporte le plus grand risque relatif de collision mortelle. Une réduction de vitesse des embarcations fréquentant le corridor des navettes diminuerait significativement le risque de collision mortelle. Ces pistes de réflexion mèneront sans doute à d’autres études plus poussées afin de continuer à en apprendre sur l’écologie de cette espèce fascinante.

Effets des diètes de remplacement du maïs sur les performances de croissance, le pH ruminal et les paramètres biochimiques sanguins chez les veaux de grains

L’objectif de cette étude a été d’évaluer l’effet du remplacement total ou partiel du maïs d’une ration alimentaire standard (MS) sur les performances de croissance, le pH ruminal et les paramètres biochimiques sanguins chez les veaux de grain de race Holstein. Quatre groupes de 80 veaux ont été répartisen32 parcs (10 veaux/parc) et ont été assignés au hasard à quatre rations alimentaires. Les rations alimentaires ont été: la ration standard qui est constituée de maïs et un supplément protéique à 43,6% de protéine brute (MS);une ration réduite de maïs, avec tourteau de canola et de drèche de distillerie de maïs avec soluble (MCD); une ration réduite de maïs, avec supplément protéique à 43,6% de protéine brute et de drèche de distillerie de maïs avec soluble (MSD); et finalement une ration d’orge roulé, de tourteau de canola et de drèche de distillerie de maïs avec soluble (OCD). Les rations alimentaires ont été formulées selon une phase de démarrage P1 (j0 à j54), une de croissance P2 (j55 à j85) et une de finition P3 (j86 à j96). Un groupe additionnel de 5 veaux contrôle (CT), a reçu une ration alimentaire non acidogène à base de fourrage et de concentré. Notons qu’avant le début des traitements alimentaires au j0, sauf CT, les veaux ont reçu une ration d’adaptation contenant du maïs et de l’orge (50-50) et un supplément protéique pendant 20j. Les gains moyens quotidiens (GMQ) ont été similaires aux périodes P1 (0j-j27, j28-j54) et P2 (j55-j85), mais à la période P3 (j86-j96), le GMQ de la ration OCD a été plus grand que ceux dans les autres rations (p<0.001). Le rendement carcasse des veaux abattus au poids vifs d’environ 267 kg, de la ration OCD a été plus petit que ceux des rations MS et MSD (p<0.002). La matière sèche ingérée (MSI) a diminué pour le groupe MSD au j96, comparée à celles des groupes MS et BCD (p<0.001). Cependant, les rations alimentaires n’ont pas eu d’effet sur le poids vif des veaux. Les durées moyennes en dessous du pH ruminal de 5.6 (DpH5.6 en h.j.-1) du j68 au j85 (P2) ont été similaires pour les groupes CT et OCD (p=0.09) et plus petites (p<0.001) que celles des groupes du MS, MCD et MSD. Pendant la phase P3, les DpH5.6 des groupes de MS, MCD et MSD, ont été similaires (p>0.83), mais plus grandes que celle du groupe de OCD (p<0.0001). Les DpH5.6 n’ont pas eu d’effet sur les GMQ. Aux j68 et j96, les rations alimentaires n’ont pas eu d’effet sur la L-lactate (p > 0.05), le pH sanguin (p > 0.001; non significatif après l’ajustement de Bonferroni :NSAB) et le trou anionique (p > 0.009; NSAB). La PCO2 des animaux du groupe MS a été plus grande que celle du groupe CT (p = 0.0003). Au j68, HCO3 - du groupe CT a été plus grande que celle du groupe MCD (p = 0.0008). Les traitements alimentaires n’ont pas d’effets sur la lipopolysaccharide binding protein (LBP) aux j0 et j68. Au j96, la LBP du groupe CT a été plus petite que celle du groupe MS et MCD (p=0.001). Les diètes n’ont pas d’effets significatifs sur les épithéliums et les lamina propria du rumen (p0>0.37), ainsi que sur les abcès du foie (p=0.80). Le remplacement total du maïs par l’orge roulé, la drêche de distillerie de maïs avec soluble et le tourteau de canola amélioré le GMQ en phase de finition, a amélioré le pH du rumen, le rapprochant du pH ruminal physiologique, n’a pas modifié les paramètres biochimiques sanguins qui ont été mesurés et a diminué le rendement carcasse moyen de 1,1%.

Studies on the Biology, Ecology and Fishery of the sea cucumber Holathuria (hetriatyla) scabra (Jaeger) from southeast coast of India

The distribution of the holothurian H. KH.) scabra indicated its availability all along coastal areas on Palk Bay from Rameswavam to Mallipattinam and along the Gulf of Hannah coast from Pamban to Ervadi and Tuticmhin,'at 4~2O m depth.The major fishing for holmthurians was done by skin diving at all the centres. The tallu valai was operated at Tuticorin and Vedalai and trawlevs were operated at Rameswaram.The fmod of H. KN.) scabra consists of ovganic matter which contains mud, sand, shell debris, bivalves and algae. Obsehvatinns indicated the species seems to be a n0n—se1ective feeder. The assimilation efficiency from sediment to faeces indicated that the faecal pellets of H. KH.) scabra are semidigested.A multiple relationship was fitted between total length, total weight, gutted weight, gonad weight and maturity stages were found significant.The fishing season for holothurians commences from October to March along Gulf of Manner coast and from March to October along Palk Bay coast.The percentage of catches recorded by skin diving, trawlere and tallu valai were 80.04%, 10.27% and 9.69% respectively. Skin diving contributes to maximum catch.The holothurians landed all along the Gulf of Manner and Palk Bay coasts constitute 25.6% and 74.4% respectively. This showed that Palk Bay coast is more productive.

An Investigation into OccasionalWhite Spot Syndrome Virus Outbreak in Traditional Paddy CumPrawn Fields in India

A yearlong (September 2009–August 2010) study was undertaken to find out possible reasons for occasional occurrence of White Spot Syndrome Virus (WSSV) outbreak in the traditional prawn farms adjoining Cochin backwaters. Physicochemical and bacteriological parameters of water and sediment from feeder canal and four shrimp farms were monitored on a fortnightly basis. The physicochemical parameters showed variation during the two production cycles and between the farms studied. Dissolved oxygen (DO) content of water fromfeeder canal showed low oxygen levels (as low as 0.8mg/L) throughout the study period. There was no disease outbreak in the perennial ponds. Poor water exchange coupled with nutrient loading from adjacent houses resulted in phytoplankton bloom in shallow seasonal ponds which led to hypoxic conditions in early morning and supersaturation of DO in the afternoon besides considerably high alkaline pH. Ammonia levels were found to be very high in these ponds.WSSV outbreak was encountered twice during the study leading to mass mortalities in the seasonal ponds. The hypoxia and high ammonia content in water and abrupt fluctuations in temperature, salinity and pH might lead to considerable stress in the shrimps triggeringWSSV infection in these traditional ponds

Effect of management strategies on the performance of ruminant livestock production systems and the safety of plant and animal products in the city of Sikasso, Mali

The regional population growth in West Africa, and especially its urban centers, will bring about new and critical challenges for urban development policy, especially in terms of ensuring food security and providing employment for the growing population. (Peri-) urban livestock and vegetable production systems, which can contribute significantly to these endeavours, are limited by various constraints, amongst them limited access to expensive production factors and their (in)efficient use. To achieve sustainable production systems with low consumer health risks, that can meet the urban increased demand, this doctoral thesis determined nutrient use efficiencies in representative (peri-) urban livestock production systems in three West African cities, and investigated potential health risks for consumers ensuing from there. The field study, which was conducted during July 2007 to December 2009, undertook a comparative analysis of (peri-) urban livestock production strategies across 210 livestock keeping households (HH) in the three West African cities of Kano/Nigeria (84 HH), Bobo Dioulasso/Burkina Faso (63 HH) and Sikasso/Mali (63 HH). These livestock enterprises were belonging to the following three farm types: commercial gardening plus field crops and livestock (cGCL; 88 HH), commercial livestock plus subsistence field cropping (cLsC; 109 HH) and commercial gardening plus semi-commercial livestock (cGscL; 13 HH) which had been classified in a preceding study; they represented the diversity of (peri-) urban livestock production systems in West Africa. In the study on the efficiency of ruminant livestock production, lactating cowsand sheep herd units were differentiated based on whether feed supplements were offered to the animals at the homestead (Go: grazing only; Gsf: mainly grazing plus some supplement feeding). Inflows and outflows of nutrients were quantified in these herds during 18 months, and the effects of seasonal variations in nutrient availability on animals’ productivity and reproductive performance was determined in Sikasso. To assess the safety of animal products and vegetables, contamination sources of irrigated lettuce and milk with microbiological contaminants, and of tomato and cabbage with pesticide residues in (peri-) urban agriculture systems of Bobo Dioulasso and Sikasso were characterized at three occasions in 2009. Samples of irrigation water, organic fertilizer and ix lettuce were collected in 6 gardens, and samples of cabbage and tomato in 12 gardens; raw and curdled milk were sampled in 6 dairy herds. Information on health risks for consumers of such foodstuffs was obtained from 11 health centers in Sikasso. In (peri-) urban livestock production systems, sheep and goats dominated (P<0.001) in Kano compared to Bobo Dioulasso and Sikasso, while cattle and poultry were more frequent (P<0.001) in Bobo Dioulasso and Sikasso than in Kano. Across cities, ruminant feeding relied on grazing and homestead supplementation with fresh grasses, crop residues, cereal brans and cotton seed cake; cereal grains and brans were the major ingredients of poultry feeds. There was little association of gardens and livestock; likewise field cropping and livestock were rarely integrated. No relation existed between the education of the HH head and the adoption of improved management practices (P>0.05), but the proportion of HH heads with a long-term experience in (peri-) urban agriculture was higher in Kano and in Bobo Dioulasso than in Sikasso (P<0.001). Cattle and sheep fetched highest market prices in Kano; unit prices for goats and chicken were highest in Sikasso. Animal inflow, outflow and dairy herd growth rates were significantly higher (P<0.05) in the Gsf than in the Go cattle herds. Maize bran and cottonseed expeller were the main feeds offered to Gsf cows as dry-season supplement, while Gsf sheep received maize bran, fresh grasses and cowpea pods. The short periodic transhumance of Go dairy cows help them maintaining their live weight, whereas Gsf cows lost weight during the dry season despite supplement feeding at a rate of 1506 g dry matter per cow and day, resulting in low productivity and reproductive performance. The daily live weight gains of calves and lambs, respectively, were low and not significantly different between the Go and the Gsf system. However, the average live weight gains of lambs were significantly higher in the dry season (P<0.05) than in the rainy season because of the high pressure of gastrointestinal parasites and of Trypanosoma sp. In consequence, 47% of the sheep leaving the Go and Gsf herds died due to diseases during the study period. Thermo-tolerant coliforms and Escherichia coli contamination levels of irrigation water significantly exceeded WHO recommendations for the unrestricted irrigation of vegetables consumed raw. Microbial contamination levels of lettuce at the farm gate and the market place in Bobo Dioulasso and at the farm gate in Sikasso were higher than at the market place in Sikasso (P<0.05). Pesticide residues were detected in only one cabbage and one tomato sample and were below the maximum residue limit for consumption. Counts of thermo-tolerant coliforms and Escherichia coli were higher in curdled than in raw milk (P<0.05). From 2006 to x 2009, cases of diarrhea/vomiting and typhoid fever had increased by 11% and 48%, respectively, in Sikasso. For ensuring economically successful and ecologically viable (peri-) urban livestock husbandry and food safety of (peri-) urban foodstuffs of animal and plant origin, the dissemination and adoption of improved feeding practices, livestock healthcare and dung management are key. In addition, measures fostering the safety of animal products and vegetables including the appropriate use of wastewater in (peri-) urban agriculture, restriction to approve vegetable pesticides and the respect of their latency periods, and passing and enforcement of safety laws is required. Finally, the incorporation of environmentally sound (peri-) urban agriculture in urban planning by policy makers, public and private extension agencies and the urban farmers themselves is of utmost importance. To enable an efficient (peri-) urban livestock production in the future, research should concentrate on cost-effective feeding systems that allow meeting the animals’ requirement for production and reproduction. Thereby focus should be laid on the use of crop-residues and leguminous forages. The improvement of the milk production potential through crossbreeding of local cattle breeds with exotic breeds known for their high milk yield might be an accompanying option, but it needs careful supervision to prevent the loss of the local trypanotolerant purebreds.

Influence of pre-plant densities of Meloidogyne incognita on growth and root infestation of spinach (Spinacia oleracea L.) (Amaranthaceae) – an important dimension towards enhancing crop production

Vegetables represent a main source of micro-nutrients which can improve the health status of malnourished poor in the world. Spinach (Spinacia oleracea L.) is a popular leafy vegetable in many countries which is rich with several important micro-nutrients. Thus, consuming Spinach helps to overcome micro-nutrient deficiencies. Pests and pathogens act as major yield constraints in food production. Root-knot nematodes, Meloidogyne species, constitute a large group of highly destructive plant pests. Spinach is found to be highly susceptible for these nematode attacks. Though agricultural production has largely benefited from modern technologies and innovations, some important dimensions which can minimize the yield losses have been neglected by most of the growers. Pre-plant or initial nematode density in soil is a crucial biotic factor which is directly responsible for crop losses. Hence, information on preplant nematode densities and the corresponding damage is of vital importance to develop successful control procedures to enhance crop production. In the present study, effect of seven initial densities of M. incognita, i.e., 156, 312, 625, 1250, 2,500, 5,000 and 10,000 infective juveniles (IJs)/plant (equivalent to 1000cm3 soil) on the growth and root infestation on potted spinach plants was determined in a screen house. In order to ensure a high accuracy, root infestation was ascertained by the number of galls formed, the percentage galled-length of feeder roots and galled-feeder roots, and egg production, per plant. Fifty days post-inoculation, shoot length and weight, and root length were suppressed at the lowest IJs density. However, the pathogenic effect was pronounced at the highest density at which 43%, 46% and 45% reduction in shoot length and weight, and root length, respectively, was recorded. The highest reduction in root weight (26%) was detected at the second highest density. The Number of galls and percentage galled-length of feeder roots/per plant showed significant progressive increase across the increasing IJs density with the highest mean value of 432.3 and 54%, respectively. The two shoot growth parameters and root length showed significant inverse relationship with the increasing gall formation. Moreover, the shoot and root length were shown to be mutually dependent on each other. Suppression of shoot growth of spinach greatly affects the grower’s economy. Hence, control measures are essentially needed to ensure a better production of spinach via reducing the pre-plant density below the level of 0.156 IJs/cm3.

Impacto ambiental de un nuevo modelo de sistema de transporte público para Caracas

En el ámbito urbano una de las principales fuentes contaminantes del ambiente son los vehículos automotores. Una estrategia para reducir el número de los vehículos en circulación y frenar el deterioro ambiental es el mejoramiento del sistema de transporte público y estimular su uso. Para hacer atractivo el empleo del transporte público en Caracas es indispensable hacer cambios importantes en este. Se propone la implantación de un sistema de Bus Rapid Transit (BRT) que responda a los deseos de movilización de la población expresados en la Encuesta de Movilidad de 2005. En dicha ropuesta, las líneas de la red de transporte masivo existente constituirían rutas troncales del sistema más importantes; el BRT contemplaría la operación de estas rutas a lo largo del eje este-oeste de la iudad y de los principales corredores viales de los valles secundarios localizados al suroeste y sureste de Caracas; y las rutas alimentadoras operarían desde distintos sectores hacia las rutas troncales. La estimación del impacto ambi  tal derivado de la implantación del sistema propuesto, calculado solo con base en la sustitución de unidades minibús por autobuses en los principales corredores, señala ahorros sustanciales en consumo de espacio y de combustible; una disminución moderada del ruido; y reducciones de las emisiones de monóxido de carbono (CO), óxidos de nitrógeno (NOx) e hidrocarburos (HC).

Bird feeders and their effects on bird-window collisions at residential houses

Feeding wild birds creates an important link between homeowners and conservation. The effects of bird feeders and year-round feeding on birds have not been well studied, however, particularly in relationship to bird-window collisions. We determined effects of bird feeder presence and placement on bird-window collisions at residential homes. Paired month-long trials in which a feeder was either present or absent for one month and then removed or added for the second month were completed at 55 windows at 43 houses. In each trial, homeowners were asked to search their study window daily for evidence of a bird-window collision. During the study there were 51 collisions when there was no bird feeder and 94 when the feeder was present. The season when each trial was set up was the best individual predictor of bird-window collisions. The largest number of collisions was observed during fall migration and the lowest during the winter months. There were no collisions at 26 of the study windows. High variance was observed in the number of collisions at different houses, indicating that effects of bird feeders are context dependent. Changing the occurrence, timing, and placement of feeders can alter collision rates but is only one of many factors that influence whether a residential house is likely to have a bird window-collision or not.

Comparing the results of recall surveys and standardized searches in understanding bird-window collisions at houses

Every year a large number of birds die when they collide with windows. The actual number is difficult to ascertain. Previous attempts to estimate bird-window collision rates in Canada relied heavily on a prior citizen-science study that used memory-based surveys. Such an approach to data collection has many potential biases. We built upon this study and its recommendations for future research by creating a citizen-science program that actively searched for collision evidence at houses and apartments for an extended period with the objective to see how standardized approaches to data collection compared with memory recall. Absolute collision estimates as well as relative differences were compared between residence types in the two studies, and we found considerable differences in absolute values for collisions but similar rankings of collision rates between residence types. Collision recall rates in our study (56.5%) were very similar those in the prior 2012 study, where 50.5% of participants remembered a bird colliding with a window at some time in the past. Fatality estimates, however, were 1.4 times higher in the 2012 study than in our study based on standardized searches. Rural houses with a bird feeder consistently had the highest number of collisions. This suggests that memory recall surveys may be a useful tool for understanding the relative importance of different risk factors causing bird-window collisions.

Tolerance of ruminant animals to high dose in-feed administration of a selenium-enriched yeast

The objective of the study was to determine if there were adverse effects on animal health and performance when a range of ruminant animals species were fed at least 10 times the maximum permitted European Union (EU) selenium (Se) dietary inclusion rate (0.568 mg Se/kg DM) in the form of selenium enriched yeast (SY) derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060. In a series of studies, dairy cows, beef cattle, calves and lambs were offered either a control diet which contained no Se supplement or a treatment diet which contained the same basal feed ingredients plus a SY supplement which increased total dietary Se from 0.15 to 6.25, 0.20 to 6.74, 0.15 to 5.86 and 0.14 to 6.63 mg Se/kg DM, respectively. The inclusion of the SY supplement (P < 0.001) increased whole blood Se concentrations, reaching maximum mean values of 716, 1,505, 1,377, and 724 ng Se/mL for dairy cattle, beef cattle, calves and lambs, respectively. Selenomethionine accounted for 10% of total whole blood Se in control animals whereas the proportion in SY animals ranged between 40 and 75%. Glutathione peroxidase (EC 1.11.1.9) activity was higher (P < 0.05) in SY animals when compared with controls. A range of other biochemical and hematological parameters were assessed, but few differences of biological significance were established between treatments groups. There were no differences between treatment groups within each species with regard to animal physical performance or overall animal health. It was concluded that there were no adverse effects on animal health, performance and voluntary feed intake to the administration of at least ten times the EU maximum, or approximately twenty times the US FDA permitted concentration of dietary Se in the form of SY derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060.

Major advances in fundamental dairy cattle nutrition

Fundamental nutrition seeks to describe the complex biochemical reactions involved in assimilation and processing of nutrients by various tissues and organs, and to quantify nutrient movement (flux) through those processes. Over the last 25 yr, considerable progress has been made in increasing our understanding of metabolism in dairy cattle. Major advances have been made at all levels of biological organization, including the whole animal, organ systems, tissues, cells, and molecules. At the whole-animal level, progress has been made in delineating metabolism during late pregnancy and the transition to lactation, as well as in whole-body use of energy-yielding substrates and amino acids for growth in young calves. An explosion of research using multicatheterization techniques has led to better quantitative descriptions of nutrient use by tissues of the portal-drained viscera (digestive tract, pancreas, and associated adipose tissues) and liver. Isolated tissue preparations have provided important information on the interrelationships among glucose, fatty acid, and amino acid metabolism in liver, adipose tissue, and mammary gland, as well as the regulation of these pathways during different physiological states. Finally, the last 25 yr has witnessed the birth of "molecular biology" approaches to understanding fundamental nutrition. Although measurements of mRNA abundance for proteins of interest already have provided new insights into regulation of metabolism, the next 25 yr will likely see remarkable advances as these techniques continue to be applied to problems of dairy cattle biology. Integration of the "omics" technologies (functional genomics, proteomics, and metabolomics) with measurements of tissue metabolism obtained by other methods is a particularly exciting prospect for the future. The result should be improved animal health and well being, more efficient dairy production, and better models to predict nutritional requirements and provide rations to meet those requirements.

Do EU direct payments to beef producers belong in the 'blue box'?

In the Uruguay Round Agreement on Agriculture, so-called 'blue box' support measures were exempted from reduction commitments, provided they were delivered under 'production-limiting' programs. Although classified as 'blue box', the EU system of direct payments (DP) to beef farmers imposes 'claim-limiting' restrictions rather than 'production-limiting' restrictions, allowing farmers to keep additional animals over and above the number upon which they are eligible to claim DP. The present paper provides empirical evidence that EU direct payments capitalise into the market prices of male calves and young steers in Ireland. It is also likely that DP capitalises into the prices of beef cows and heifers. Given this capitalisation process, some farmers can obtain 'capitalised' DP on animals produced over and above the 'claim-limiting' restrictions, by selling these animals through auction markets. Thus, 'capitalised' DP probably encourages production over and above the limiting measures.

The effects of a short-term increase in supplementation on the reproduction performance in lactating crossbred dairy cows

The hypothesis that dairy cows partially suckling their calves would ovulate following removal of calves when restored to positive energy balance by a short-term increase in supplementation was investigated in 65 crossbred cows. Five treatments (T1, T2, T3, T4, and T5) that differed in the amount of total concentrate fed from calving to week 24 were involved. Calves were allowed to suck residual milk to 12 weeks of age. Energy balance was estimated by measuring intake, milk yield and organic matter digestibility. The occurrence of ovulation was determined by the analysis of milk progesterone (P4) concentration. Four groups that were receiving additional supplementation were restored to positive energy balance, while the control group (T I) remained in negative energy balance. The percentage of cows ovulating was 36%, 58%, 92%, 90% and 60% for T1, T2, T3, T4 and T5, respectively (P = 0.026). Comparison of the timing of ovulation for combined results from T1+T2 and T3+T4+T5 estimated mean time to fail to ovulate as 110 +/- 9.0 and 87 +/- 7.6 days, respectively (p = 0.023). The percentage of the cows showing oestrus was 9%, 8%, 33%, 40% and 40% for T1, T2, T3, T4 and T5, respectively (P = 0.197). Short-term increases in supplementation are unlikely to be an attractive means of reducing calving intervals.

Some factors affecting variation in milk yield in crossbred dairy cows on smallholder farms in north-east Tanzania

A 2-year longitudinal survey was carried out to investigate factors affecting milk yield in crossbred cows on smallholder farms in and around an urban centre. Sixty farms were visited at approximately 2-week intervals and details of milk yield, body condition score (BCS) and heart girth measurements were collected. Fifteen farms were within the town (U), 23 farms were approximately 5 km from town (SU), and 22 farms approximately 10 km from town (PU). Sources of variation in milk yield were investigated using a general linear model by a stepwise forward selection and backward elimination approach to judge important independent variables. Factors considered for the first step of formulation of the model included location (PU, SU and U), calving season, BCS at calving, at 3 months postpartum and at 6 months postpartum, calving year, herd size category, source of labour (hired and family labour), calf rearing method (bucket and partial suckling) and parity number of the cow. Daily milk yield (including milk sucked by calves) was determined by calving year (p < 0.0001), calf rearing method (p = 0.044) and BCS at calving (p < 0.0001). Only BCS at calving contributed to variation in volume of milk sucked by the calf, lactation length and lactation milk yield. BCS at 3 months after calving was improved on farms where labour was hired (p = 0.041) and BCS change from calving to 6 months was more than twice as likely to be negative on U than SU and PU farms. It was concluded that milk production was predominantly associated with BCS at calving, lactation milk yield increasing quadratically from score 1 to 3. BCS at calving may provide a simple, single indicator of the nutritional status of a cow population.

Long-term response of the nematode community to elevated atmospheric CO2 in a temperate dry grassland soil

Long-term effects of the elevated atmospheric CO2 on biosphere have been in focus of research since the last few decades. In this experiment undisturbed soil monoliths of loess grassland were exposed to an elevated CO2 environment (two-times the ambient CO2 level) for a period of six years with the aid of the open top chamber method. Control without a chamber and CO2 elevation was applied as well. Elevated CO2 level had very little impact oil soil food web. It did not influence either root and microbial biomass or microbial and nematode community structure. The only significant response was that density of the bacterial feeder genus Heterocephalobus increased in the chamber with elevated CO2 concentration. Application of the open top chambers initiated more changes on nematodes than the elevated CO2 level. Open top chamber (OTC) method decreased nematode density (total and plant feeder as well) to less than half of the original level. Negative effect was found on the genus level in the case of fungal feeder Aphelenchoides, plant feeder Helicotylenchus and Paratylenchus. It is very likely that the significantly lower belowground root biomass and partly its decreased quality reflected by the increased C/N ratio are the main responsible factors for the lower density of the plant feeder nematodes in the plots of chambers. According to diversity profiles, MI and MI(2-15) parameters, nematode communities in the open top chambers (both on ambient and elevated CO2 level) seem to be more structured than those under normal circumstances six years after start of the experiment.