Acacia angustissima intoxication of Menz lambs requires two components

This study sought to determine if sheep suffer neurological symptoms when fed Acacia angustissima leaves, and whether an equivalent amount of 70% acetone extract would have the same effect. In addition, the study tried to determine if treatment of leaves with 70% acetone would destroy the activity of A. angustissima toxins, and whether extraction with 70% aqueous acetone extract would separate two components of a toxic system. Twenty-five Menz lambs were randomly assigned to one of five treatments (1) A angustissima leaves as half the diet, 2) dried extract (70% aqueous acetone) of the same quantity of leaves, 3) a corresponding amount of residues, 4) a recombination of the dried extract and dried residue, or (5) a control diet containing no A angustissima leaves or extract fractions. All animals fed the leaves and the recombined fractions died or were euthanized when they were observed to be dying of severe neurological derangement. None of the other animals showed any neurological signs of impairement. The results of this study indicate that healthy, well-fed sheep can be poisoned by A angustissima, that the toxins are not destroyed by acetone or oven drying, and that severe neurological intoxication requires two components, which can be separated by acetone extraction

Effect of age and live weight at first calving on milk yield of crossbred (Friesian x Zebu) heifers on first lactation

This paper Reports on both the individual and combined effects of age at first caving (AFC) and live weight at first calving (LWFC) for crossbred heifers (Friesian x Zebu) on first lactation Milk yield. Optimal health and nutrition management was followed. Fifty one heifers were allocated to younger. (Y) and older (O) age groups. Within each AFC groups heifers were blocked according to live weight as lighter (L) and heavier (H) live weight groups. Mean AFC and LWFC of the treatment groups were 37.4 months, 45.2 months, and 320.2 kg and 419.4 kg, respectively. Heifers calving at O age produced 6% (90.4 ,t) more milk than Y age group while L live weight treatment heifers produced 29.3% less .milk than H live weight treatment animals. Heifers calving Y_H treatment group produced 17.7% (259 t.) more milk than those calving at Y_L group. Heifers calving in O_L treatment heifers had 39.4% less milk output than O_ H treatment heifers over 305days, indicating greater effect of LWFC than AFC. Milk production increased by 4.3 t. and 41.6 t. for every increase in 1 kg of LWFC and a month in AFC, respectively. The combined effects of AFC and LWFC were significant (P< 0.001) and showed that the effects of one month reduction in age at first calving can be offset by 5.3 kg increase in live weight at first calving

Lifetime under-nutrition and lactation performance of Zebu and Zebu x Holstein cows in the tropics

Insufficient feed supply is a major limiting factor for milk production in the tropics. The aim of this study was to assess the effects of feeding level on live-weight and performance of Zebu (Boran) and crossbred (Boran × Holstein, 50–75% Holstein) lactating cows. Twenty-four heifers of each breed 20 to 36 months of age were allocated to three feeding levels (1.0, 1.2 and 1.4 times of maintenance energy requirements) until the end of the second lactation. The results of the two lactations are reported here. The diet consisted of grass hay and wheat bran in a ratio 2:1. A mineral block and water were given ad libitum. In both lactations, increasing feeding level resulted in higher daily milk yields by cross- bred but not by Zebu cows. Milk composition was not affected by level of nutrition. How- ever, the milk of Zebu cows contained more fat, protein and solids than that of crossbred cows. Average live-weights during lactation increased with feeding level in both breeds but the response was higher in crossbred cows. However, the effect of feeding level on weight changes during the lactation was not significant. Lactation length significantly differed between genotypes. Zebu cows ceased producing milk at less than 250 days after calving whereas crossbred cows had more than 300 days of lactation. The calving interval did not differ between genotypes. Compared to the first lactation, live-weight and milk yield were maintained and lactation length slightly decreased in the second lactation. These results suggest that the response to increased feeding level of crossbred cows is higher than that of Zebu cows. Therefore, crossbreds would be an appropriate option in those areas where more and better quality feed can be produced and with access to milk markets

Long-term response to feeding level in lactational performance of Boran (Bos indicus) and Boran X Holstein cows

In an experiment lasting from 1.5 years before, first calving until third parturition, 24 purebred indigenous Bos indicus (Boran) cows and 24 Boran crosses will; Holstein (proportionately 0.50 and 0 75 Holstein blood level) were given a diet composed of Bermuda grass hay and wheat bran (0 65: 0 35) offered at low, medium and high level. This level was adapted in amount to actual body weight every 2nd week corresponding to assumed 1 0, 1 2 and 1 4 times maintenance energy requirements. Cows were subjected to working exercise before and after first parturition. Body weight differences (lower with low and medium feeding level) developed mostly before calving for the first time and showed the typical decline at the start of lactation and increase in the dry period. Additionally, Boran cows given the high level increased their body weight from the first to the second lactation cycle. Body condition scores were higher in the Boran cows and, in both genotypes, with high feeding level. Independent of feeding level and genotype, calving intervals in cycles 1 and 2 were 530 and 421 days, respectively. Lactation length was considerably shorter in the Boran cows than in the crossbred cows. Milk yield, calculated over the first 13 weeks of lactation and over the whole lactation in both cycles, was 2.06 and 3.06 times higher in the crossbreds than in the Boran. Milk of Boran cows had 1 30, 1.15 and 1 20 times higher contents of fat, total solids and protein. In the first 13 weeks of lactation, milk yield of crossbreds with high feeding level (8 7 kg/day) was higher (P < 0 05) than that of the crossbreds with medium (6 5 kg/day) and low feeding level (5 4 kg/day), respectively. Boran cows never showed a significant response in milk yield to feeding level. Accordingly, the amount of organic matter intake required per kg milk increased with feeding level in the Boran cows while it remained unaffected in the crossbreds. Organic matter digestibility, as measured in lactation cycle 1, was higher (P < 0 Ol) in Boran. Response to high feeding level and estimated maintenance requirements of crossbred cows corresponded with current assumptions, but crossbreds subjected to medium feeding level expressed unexpectedly little difference from those receiving the low level. It seems that current recommendations are not generally applicable to indigenous tropical breeds as these responded differently from crossbreds to feeding level

Is it possible to mitigate greenhouse gas emissions in pastoral ecosystems of the tropics?

Climate change science has been discussed and synthesized by the world's best minds at unprecedented scales. Now that the Kyoto Protocol may become a reality, it is time to be realistic about the likelihood of success of mitigation activities. Pastoral lands in the tropics hold tremendous sequestration potential but also strong challenges to potential mitigation efforts. Here we present new analyses of the global distribution of pastoral systems in the tropics and the changes they will likely undergo in the next 50 years. We then briefly summarize current mitigation options for these lands. We then conclude by attempting a pragmatic look at the realities of mitigation. Mitigation activities have the greatest chance of success if they build on traditional pastoral institutions and knowledge (excellent communication, strong understanding of ecosystem goods and services) and provide pastoral people with food security benefits at the same time