Ethiopia maintains an extensive livestock population; however, reproductive performance of cattle and their breeding management are unsatisfactory. Currently, the sole diagnostic tool in the country is rectal palpation, which is inaccurate for early pregnancy in cattle. The study assessed reproductive performance and major reproductive problems using questionnaire survey, and evaluated simple, cost-effective alternative monitoring approaches using on-farm diagnostic tools to determine milk and serum progesterone (P4) and evaluate reproductive status. There were 177 dairy farms (range 1-115 cattle per farm) included in the questionnaire survey. Of these, 47 participated in the quantitative determination of P4 and estradiol profiles that used an enzyme-linked immunosorbent assay (ELISA) and in the on-farm diagnostic trial that used qualitative ELISA (Target P4 and Dipstick (P4 Rapid), and the reproductive status of 319 crossbred [Holstein Friesian (HF) X Zebu] dairy cattle was assessed. Questionnaires indicated that heifers in the study area reach puberty at older age and calve late, and cows have long postpartum estrus and calving interval. Anestrus, repeat-breeding, dystocia, retained fetal membranes (RFM), endometritis and abortion as the major reproductive problems in dairy cattle in the study area. Serum, milk, saliva and urine P4 and serum estradiol profiles of cattle at different reproductive status was determined using quantitative laboratory ELISA. High P4 levels was detected in pregnant and diestrus cattle than cattle that were anestrus and in-heat. Estradiol level was higher in cattle that were in-heat than cattle in other reproductive conditions. On-farm P4 ELISA indicated in-heat (estrus) 10 (3.1%), anestrus 77 (24.2%), repeater (follicular cyst) 9 (2.8%), normally cycling 69 (21.6%) and pregnant 154 (48.3%). The field P4 ELISA findings were validated using quantitative laboratory P4 ELISA, and similar results were obtained. The sensitivity and specificity of on-farm and laboratory P4 ELISA tests for diagnosing pregnancy were 88.6 & 99.4% and 98.1 & 100%, respectively. Once reproductive problems were identified using on-farm P4 ELISA and per rectal palpation, along with reproductive history, 122 cattle (75 cows and 47 heifers) were assigned to a 10-day Controlled Internal Drug Release (CIDR) in combination with prostaglandin F2-alpha (PGF2α) and equine chorionic gonadotrophin (eCG) based estrus synchronisation protocol to study the estrus response and conception rate. The overall estrus response and conception rates were 97.5% and 78.3%, respectively, with no significant differences in parity, pre-treatment reproductive status (anestrus or cycling (repeat-breeding/silent-estrus)) and farming system (smallholder vs organised commercial farms). The study has shown high estrus response and conception rate. Hence, this protocol is highly recommended to enhance fertility of dairy cattle in the study area and other regions. Finally, the study has determined the macronutrient composition of milk and assessed the effect of reproductive status, farm (nutritional) management, stages of lactation, parity and breed on milk composition in 246 dairy cows. This consisted of 184 crossbred cows from smallholder (n= 76: 36 non-pregnant and 40 pregnant) and organised commercial dairy farms (n= 108: 62 non-pregnant and 46 pregnant) in and around Mekelle, Ethiopia and by way of comparison, 62 HF cows (25 non-pregnant and 37 pregnant), either managed indoors or outdoors in a commercial farm in Edinburgh, United Kingdom. The mean milk fat, protein, lactose, total solid (TS) and solid-no-fat (SNF) recorded were 2.36%, 3.46%, 4.37%, 10.39% and 7.82%, in crossbred dairy cows, compared with 5.05%, 3.71%, 4.72%, 13.68% and 8.43%, in HF cows, respectively. Significantly lower (p < 0.05) level of macronutrient was recorded in milk from crossbred cows than HF cows. Milk fat in both breeds was affected by reproductive status, farm (nutritional) management and stages of lactation, but not by parity. In both cattle breeds, the milk fat content was significantly higher (p < 0.05) in pregnant than non-pregnant cows. Milk protein content was significantly (p < 0.05) affected by reproductive status (in crossbreds) and stages of lactation (in both breeds), but not by farm management or parity. Reproductive status (in crossbreds), stages of lactation (in both breeds) and parity (in crossbreds) affected lactose level; however, farm management had no effect on lactose level in both breeds. Milk fat was the most affected macronutrient content in both breeds. Low milk fat level in crossbred cows could be as a result of samples obtained from early milking coupled with nutritional management. In conclusion, the present study has determined the major reproductive problems in crossbred dairy cattle, assessed their actual reproductive status using rapid, cost effective, simple and applicable on-farm P4 tests, and established P4 and estradiol profiles at different reproductive status. The major breeding problem was poor estrus detection evidenced when animals reported anestrus were confirmed normally cycling using on-farm as well as laboratory P4 assays. These studies offer opportunities for establishing simple field reporting of reproductive status in these crossbred dairy cattle, which can have a major impact on breeding management and productivity.

The objectives of this study were to evaluate the effect of Leptospirosis on reproductive and productive performance for dairy breeds cows and to identify the inheritance of this disease by estimating the coefficient of heritability. There were used 1,788 test day milk records, measured in 115 Holstein, 16 Jersey and 18 crossbred cows, daughters of 51 bulls, collected between June/2007 and February/2008 in six herds raised in the Western Region of Santa Catarina State. The file contained the following information: identification of animal (cow) and his father, date of the cow birth, date of the last delivery, test day milk production; reproductive history, Leptospirosis serology, nutrition and health management and outcome of treatment. The effect of Leptospirosis on milk production was evaluated by comparing the performance of serum positive animals, before and after the treatment, through the Test PDIFF, while the effect on the reproductive characteristics were evaluated through the test of the "Qui" Square, relating the serology for Leptospirosis and the reproductive history of animals. The Leptospirosis inheritance probability was evaluated by the coefficient of heritability for serology and for this, there were used 125 records measured in 97 Holstein, 10 Jersey and 18 crossbred cows, daughters of 27 bulls. The results of this study show that Leptospirosis causes reproductive problems, since 70.67% of the animals with positive serology for the disease showed reproductive problems such as repetition of estrus, abortion and prolonged anestrous. Leptospirosis also causes reduction in milk production, since the serum positive animals yielded an average 20.09 liters/day before being treated and, 22.01 liters/day after the treatment, difference equivalent to 1.92 liters/day. The coefficient of heritability of 36% shows that it is possible to produce a population more resistant to the disease by selection. / Os objetivos do presente estudo foram avaliar o efeito da Leptospirose sobre o desempenho reprodutivo e produtivo de vacas de raças leiteiras e identificar o tipo de herança desta enfermidade através da estimativa do coeficiente de herdabilidade. Foram utilizados 1.788 registros de produção de leite no dia do controle, mensurados em 115 vacas da raça Holandesa, 16 Jersey e 18 Mestiças, filhas de 51 touros, coletados entre os meses de junho de 2007 a fevereiro de 2008 em seis rebanhos na Região Oeste do Estado de Santa Catarina. O arquivo continha as seguintes informações: identificação do animal (vaca) e do seu pai; data de nascimento da vaca, do último parto e dos controles leiteiros; histórico reprodutivo, manejo nutricional e sanitário, sorologia para a Leptospirose e resultado de tratamento. O efeito da Leptospirose sobre a produção de leite foi avaliado comparando o desempenho dos animais soropositivos, antes e após o tratamento terapêutico, através do Teste PDIFF, enquanto que o efeito sobre as características reprodutivas foi avaliado através do Teste do Qui Quadrado, relacionando a sorologia para Leptospirose e o histórico reprodutivo dos animais. A probabilidade de herança da Leptospirose foi avaliada pelo coeficiente de herdabilidade da titulação sorológica e para isto foram utilizados 125 registros mensurados em 97 vacas da raça Holandesa, 10 Jersey e 18 Mestiças, filhas de 27 touros. Os resultados do presente trabalho mostram que a Leptospirose causa problemas de ordem reprodutiva, visto que 70,67% dos animais com sorologia positiva para a doença apresentaram problemas reprodutivos, tais como, repetição de cio, aborto e anestro prolongado. A Leptospirose também provocou redução na produção de leite, uma vez que os animais soropositivos produziram, em média, 20,09 litros/controle antes de serem tratadas e, após o tratamento terapêutico, produziram 22,01 litros de leite/controle em média, uma diferença equivalente a 1,92 litros de leite por vaca/dia. O coeficiente de herdabilidade de 36% mostra que é possível produzir uma população mais resistente a esta doença através da seleção.