Sustainable animal agriculture and crisis mitigation in livestock-dependent systems in southern Africa

These proceedings contain papers, abstracts and posters of the Regional Conference on Sustainable Animal Agriculture and Crisis Mitigation in Livestock-dependent Systems in Southern Africa that took place at Malawi Institute of Management (MIM) in Lilongwe, Malawi, from 30th October to 1st November 2000. A keynote paper opens each theme and is followed by scientific contributions, short communications, and abstracts. Posters are published as short communications and/or abstracts. These proceedings are organised as follows: Session 1 Livestock Management and Improvement (16 papers) Session 2 Policy Analysis, Socio-economics and Sustainable Integrated Animal Health (4 papers) Session 3 Crisis Mitigation in Livestock-dependent Systems - Held as a mini workshop within the conference (2 papers) Session 4 Product Enhancement and Human Resources Development (4 papers) Session 5 Short Communications (4 papers) Session 6 Abstracts (10 abstracts

Phenotypic and genetic parameters for selected production and reproduction traits of Mpwapwa cattle in low-input production systems

The objective of this study was to assess the genetic improvement programme of the Mpwapwa dairy cattle breed over the past four decades, based on on-station selection and breeding. Estimates of genetic parameters and genetic trends for total lactation milk yield (LMY), 305-day lactation milk yield (305LMY), lactation length (LL), age at first calving (AFC), and calving interval (CI) were derived. The study used 1,003 lactation records from 385 cows and 78 sires collected from 1967 to 2012. Genetic parameters were estimated using an animal model procedure with ASReml software. The heritability for LMY and 305LMY were moderately high (0.33 ± 0.11–0.44 ± 0.04) and low for LL (0.13 ± 0.17.0). Repeatability for LMY and 305LMY was high (0.62 ± 0.04–0.70 ± 0.03) and moderate for LL (0.27 ± 0.06). The heritability for AFC (0.13 ± 0.11) and CI (0.10 ± 0.05) were low. The repeatability for CI was low (0.10 ± 0.05). Genetic correlation of 305LMY with LMY and CI were 0.87 ± 0.02 and -0.06 ± 0.009, respectively, while the corresponding phenotypic correlation estimates were 0.82 ± 0.01 and -0.01 ± 0.001. Variation among animal estimated breeding values (EBV) was significant, suggesting that selection to improve these traits is feasible. Thirty seven out of 78 sires had favourable EBV (0–900 kg) for milk yield, which suggests that selection for specific sires could result in increased LMY. Annual rates of sires EBV change for 305LMY, LL, CI, and AFC were -0.05, 0.15, and -0.14 days, respectively. All these traits showed that a decline in genetic progress for Mpwapwa dairy cattle in the on-station breeding programme.Keywords: Fertility, genetic correlation, genetic trend, milk yield, variance component

Linking bone development on the caudal aspect of the distal phalanx with lameness during life

Claw horn disruption lesions (CHDL; sole hemorrhage, sole ulcer, and white line disease) cause a large proportion of lameness in dairy cattle, yet their etiopathogenesis remains poorly understood. Untreated CHDL may be associated with damage to the internal anatomy of the foot, including to the caudal aspect of the distal phalanx upon which bone developments have been reported with age and with sole ulcers at slaughter. The primary aim of this study was to assess whether bone development was associated with poor locomotion and occurrence of CHDL during a cow’s life. A retrospective cohort study imaged 282 hind claws from 72 Holstein-Friesian dairy cows culled from a research herd using X-ray micro–computed tomography (μ-CT; resolution: 0.11 mm). Four measures of bone development were taken from the caudal aspect of each distal phalanx, in caudal, ventral, and dorsal directions, and combined within each claw. Cow-level variables were constructed to quantify the average bone development on all hind feet (BD-Ave) and bone development on the most severely affected claw (BD-Max). Weekly locomotion scores (1–5 scale) were available from first calving. The variables BD-Ave and BD-Max were used as outcomes in linear regression models; the explanatory variables included locomotion score during life, age, binary variables denoting lifetime occurrence of CHDL and of infectious causes of lameness, and other cow variables. Both BD-Max and BD-Ave increased with age, CHDL occurrence, and an increasing proportion of locomotion scores at which a cow was lame (score 4 or 5). The models estimated that BD-Max would be 9.8 mm (SE 3.9) greater in cows that had been lame at >50% of scores within the 12 mo before slaughter (compared with cows that had been assigned no lame scores during the same period), or 7.0 mm (SE 2.2) greater if the cow had been treated for a CHDL during life (compared with cows that had not). Additionally, histology demonstrated that new bone development was osteoma, also termed “exostosis.” Age explained much of the variation in bone development. The association between bone development and locomotion score during life is a novel finding, and bone development appears specific to CHDL. Bone development on the most severely affected foot was the best explained outcome and would seem most likely to influence locomotion score. To stop irreparable anatomical damage within the foot, early identification of CHDL and effective treatment could be critical

Testing phenotypes for degree of resilience using fluctuations in milk yield of dairy cows in sub-Saharan Africa

Despite the relevance of dairy production in the fight against food insecurity and unemployment in sub-Saharan Africa (SSA), negative effects of climate change and general changes in the production environment pose huge challenges to its profitability. Thus, there is a need to improve resilience capacity of dairy animals to adapt to this changing environment. In the current study, we tested two indicators of resilience, logtransformed variance (LnVar) and Skewness (Skew) of deviation, based on fluctuations in animals’ milk yield. Further, we assessed the effects of genotype, agroecological zone, and genotype by agroecological zone (G×E) interaction for these phenotypes. Cows with less than 50% of exotic genetics had higher degree of resilience (P<0.05). Cows performing in semi-arid zones had higher resilience capacity compared to those in semi-humid environment (P<0.05). G×E did not significantly influence both indicators. The results provide valuable information that would inform dairy cattle improvement initiatives in SSA

Alternative learning technologies for developing capacity in animal breeding and genetics in middle and low income countries

In today’s world where scientific progress and development of new knowledge is increasing rapidly, middle and low income countries must be able to train and retain versatile researchers in the field of animal breeding and genetics able to analyze, adapt and use technologies, and possess strong social skills. A modernized blended learning approach with flexible organizational structures that allow the integration of face to face with virtual learning environments using various e-learning technologies needs to be adopted. However, electronic learning tools addressing situations and needs for animal genetic resource management in middle and low income countries are few, and several challenges hinder wide adoption of e-learning. This paper presents some experiences with e-learning tools in middle and low income countries, outlines opportunities for enhanced adoption of e-learning and identifies some gaps and questions that still need to be addressed to facilitate e-learning

The contribution of previous lameness events and body condition score to the occurrence of lameness in dairy herds: a study of 2 herds

It has been demonstrated that low body condition and previous occurrence of lameness increase the risk of future lameness in dairy cows. To date the population attributable fraction (PAF), which provides an estimate of the contribution that a risk factor makes toward the total number of disease events in a population, has not been explored for lameness using longitudinal data with repeated measures. Estimation of PAF helps to identify control measures that could lead to the largest improvements on-farm. The aim of this study was to use longitudinal data to evaluate the proportion of lameness that could be avoided in 2 separate herds (2 populations) through (1) reduced recurrence of previous lameness events, (2) and moving body condition score (BCS) into more optimal ranges. Data were obtained from 2 UK dairy herds: herd A, a 200-cow herd with 8 yr of data from a total of 724 cows where lameness events were based on weekly locomotion scores (LS; 1 to 5 scale), and herd B, a 600-cow herd with data recorded over 44 mo from a total of 1,040 cows where treatment of clinical cases was used to identify lameness events. The PAF for categories of BCS were estimated using a closed equation appropriate for multiple exposure categories. Simulation models were used to explore theoretical scenarios to reflect changes in BCS and recurrence of previous lameness events in each herd. For herd A, 21.5% of the total risk periods (cow-weeks) contained a lameness event (LS 3, 4, or 5), 96% of which were repeat events and 19% were recorded with BCS 16 wk before a risk period. The median PAF estimated for changes in BCS were in the region of 4 to 11%, depending on severity of lameness. Repeated bouts of lameness made a very large contribution to the total number of lameness events. This could either be because certain cows are initially susceptible and remain susceptible, due to the increased risk associated with previous lameness events, or due to interactions with environmental factors. This area requires further research