Microbiological quality of goat's milk obtained under different production systems

In order to determine the safety of milk produced by smallholder dairy goat farms, a farm-based research study was conducted on commercial dairy goat farms to compare the microbiological quality of milk produced using 3 different types of dairy goat production systems (intensive, semi-intensive and extensive). A survey of dairy goat farms in and around Pretoria carried out by means of a questionnaire revealed that most of the smallholder dairy goat farms surveyed used an extensive type of production system. The method of milking varied with the type of production system, i.e. machine milking; bucket system machine milking and hand-milking, respectively. Udder half milk samples (n=270) were analysed, of which 31.1% were infected with bacteria. The lowest intra-mammary infection was found amongst goats in the herd under the extensive system (13.3%), compared with 43.3% and 36.7% infection rates under the intensive and semi-intensive production systems, respectively. Staphylococcus intermedius (coagulase positive), Staphylococcus epidermidis and Staphylococcus simulans (both coagulase negative), were the most common cause of intramammary infection with a prevalence of 85.7% of the infected udder halves. The remaining 14.3% of the infection was due to Staphylococcus aureus. Bacteriology of bulk milk samples on the other hand, showed that raw milk obtained by the bucket system milking machine had the lowest total bacterial count (16,450 colony forming units (CFU)/ml) compared to that by pipeline milking machine (36,300 CFU/ml) or hand-milking (48,000 CFU/ml). No significant relationship was found between the somatic cell counts (SCC) and presence of bacterial infection in goat milk In comparison with the herds under the other 2 production systems, it was shown that dairy goat farming under the extensive production system, where hand-milking was used, can be adequate for the production of safe raw goat milk.     

Characterisation of smallholder dairy production systems using animal welfare and milk quality

The aim of the current study was to characterise and evaluate production system of smallholder dairy farmers using an index based on combined score of animal welfare and milk quality. Farms were grouped into three categories, tier 1, tier 2 and tier 3. To test the robustness of the characterisation, milk yield (MY), calving interval (CI) and body condition scores (BCS) were used. In the study area, the majority (66.3%) of smallholder dairy farmers practiced cut-and-carry as compared to 15.3% who grazed their cows. The rest combined cut-and-carry and grazing. Cows of farmers in tier 1 had the lowest mean MY (5.4?kg/day, SE?=?0.4), lowest mean BCS (2.1?kg/day, SE?=?0.09) and longest mean CI (603?days, SE?=?27) than farmers in tier 3, mean MY (10.8?kg/day, SE?=?0.6), mean BCS (2.6, SE?=?0.06) and mean CI (404?days, SE?=?17). The study demonstrated that a simple and yet novel method based on farm level indicators can be developed and could assist to timely identify specific problems on the farm.     

Awassi sheep reproduction and milk production: review

Awassi is the local breed of sheep in Jordan and is the most important breed in the semi-arid regions of the near east countries. Awassi ram and ewe lambs reach puberty at around 8 and 9 months of age, respectively. The breeding season of Awassi ewes starts as early as April and lasts through September. After puberty, Awassi rams are sexually active throughout the year. The normal estrous cycle in Awassi ewes is 15–20 days (average 17 days). Estrus ranges from 16–59 h (average 29 h) during the breeding season. The reproductive performance of unimproved Awassi sheep has been low while improved Awassi has the highest fertility and milk production and are the heaviest among all Awassi populations. The gestation length varies from 149 to 155 days (average 152 days). Hormones that are commonly used for induction and synchronization of estrus in Awassi ewes include progestins, gonadotropins and PGF2α. An Awassi ewe produces 40–60 and 70–80 kg of milk per 150-day lactation period under traditional and improved production systems, respectively, in addition to the suckled milk left for lambs until weaning. The improved Awassi has the highest milk production among all Awassi populations and may reach 506 L over 214-day lactation period. The objective of this review is to summarize the reproductive pattern and milk production of Awassi sheep in the Middle East region.     

Effect of feed restriction on dairy cow milk production: a review

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.     

不同添加比例的两种纤维素酶对奶牛产奶量及乳品质的影响

试验选用100头胎次、产奶量、泌乳期相近的奶牛,随机分成5组(每组20头),在试验1组、试验2组、试验3组和试验4组饲料中分别添加纤维素酶A50g/t、纤维素酶A100g/t、纤维素酶B80g/t、纤维素酶B160g/t。测定5组奶牛产奶量及乳品质,研究其对奶牛产奶量的影响。结果表明,与试验前相比,不同纤维素酶组产奶量均呈上升趋势;与对照组相比,纤维素酶组在试验全期产奶量高于对照组(P>0.05);在本试验条件下,纤维素酶可有效提高奶牛产奶量,提高经济效益,对乳品质的影响效果不明显。     

Ostertagia ostertagi antibodies in milk samples: Relationships with herd management and milk production parameters in two Mediterranean production systems of Spain

The present study analyzed Ostertagia ostertagi antibodies by indirect ELISA in milk samples in two cattle systems in Mediterranean Spain to indirectly monitor gastrointestinal nematode (GI) parasitism effects on production. Individual samples from 10 animals and the corresponding milk herd samples were collected from 133 herds in Girona (intensive management) and 123 herds in Minorca (extensive management). Both locations showed high and significant positive relationships between average optical density ratios (ODR) of individual animals and ODR in their milk tank. Although antibodies levels were low, there were significantly higher in Minorca. Negative correlations between ODR values and milk production were found in both systems. Importantly, in Minorca, average herd milk production was higher in the herds that treated their animals against GI nematodes compared to those that did not treat. The ELISA technique was valuable to indirectly assess differences in the level of GI nematode infection even in cattle production systems with low levels of infection.     

不同微生态制剂对奶牛产奶性能和乳品质的影响

[目的]研究旨在探讨不同微生态制剂对奶牛产奶性能和乳品质的影响,[方法]将40头荷斯坦奶牛随机分成4个处理组,对照组饲喂基础日粮,微生态制剂1组、微生态制剂2组、微生态制剂3组分别在基础日粮中添加0.1%的三种微生态制剂产品。[结果]结果显示：与对照组相比,微生态制剂1组、微生态制剂2组、微生态制剂3组的平均日产奶量、乳蛋白率均显著增加（P＜0.05）,体细胞数均显著降低（P＜0.05）。与对照组相比,微生态制剂1组的平均日采食量、乳脂率均显著增加（P＜0.05）,料奶比显著降低（P＜0.05）。与微生态制剂2组相比,微生态制剂1组的平均日产奶量、乳蛋白率均显著增加（P＜0.05）。[结论]说明三种微生态制剂产品均能在一定程度上提高奶牛的产奶性能和乳品质,以微生态制剂产品1的作用效果最好。     

共轭亚油酸对奶牛产奶量及乳品质的影响

试验选用体况相近的健康泌乳奶牛48头,采用单因子随机化设计,分4组。对照组饲喂基础日粮,试验组在基础日粮基础上添加共轭亚油酸分别为15g/d·头、30g/d·头、45g/d·头。结果表明:(1)在日粮中添加共轭亚油酸可使奶牛产奶量提高,添加量为30g/d·头和45g/d·头时分别比对照组提高了18.9%和17.1%(P<0.05)。(2)在日粮中添加共轭亚油酸可使牛奶乳脂率下降,添加量为30g/d·头和45g/d·头时分别比对照组下降了12.3%和10.5%(P<0.05)。     

Consequences of genetic selection for increased milk production in European seasonal pasture based systems of milk production

The data presented in this review show that past selection for increased milk production in Ireland over a 14-year period (1990 to 2003) resulted in increases in milk production per cow but has been accompanied by undesirable side effects in reproduction and survival. Economic analysis in a EU milk quota scenario over this period showed that only 41% of the potential improvement in farm profit was achieved because of impaired reproductive performance. Strain comparison studies show that genetic selection for increased phenotypic milk production, which is generally accompanied with increased proportion of North American Holstein Friesian genes, was associated with increased milk production per cow, lower body condition score, greater milk production response to concentrate supplementation at pasture and reduced fertility and survival. The lower reproductive performance observed with cows selected solely for high milk production was associated with lower energy balance in early lactation, greater partitioning of additional nutrients towards milk production, inability to achieve desired grass intake from pasture and decreased plasma glucose and insulin like growth factor-1 concentrations. The existence of genotype by environment interactions suggests that germplasm selected in the future should be from within the management system in which it is to be used, and based on a selection index that combines production and other traits of economic importance.     

Effect of paratuberculosis on culling, milk production, and milk quality in dairy herds

OBJECTIVE: To determine the effect of paratuberculosis on culling, milk production, and milk quality in infected dairy herds. DESIGN: Cross-sectional study. ANIMALS: 689 lactating dairy cows in 9 herds. PROCEDURE: Milk, blood, and fecal samples were obtained from all cows. Fecal samples were evaluated via mycobacterial culture. Serum samples were tested with a commercially available ELISA for antibodies against Mycobacterium avium subsp paratuberculosis, and preserved milk samples were tested with an ELISA for antibodies against M paratuberculosis. Mixed effect and proportional hazards models were used to determine the effect of paratuberculosis on 305-day milk, fat, and protein production; somatic cell count linear score; and the risk of culling. RESULTS: Cows with positive results of bacteriologic culture of feces and milk ELISA produced less milk, fat, and protein, compared with herdmates with negative results. No difference in 305-day milk or fat production was detected in cows with positive results of serum ELISA, compared with seronegative cows. The 3 survival analyses revealed that cows with positive results of each test were at higher risk of being culled than cows with negative results. Paratuberculosis status, as determined by use of all 3 diagnostic tests, was not associated with milk somatic cell count linear score. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for the 9 herds in this study, paratuberculosis significantly decreased milk production and cow longevity.     

Experimental intramammary inoculation with Mycoplasma bovis in vaccinated and unvaccinated cows: effect on milk production and milk quality.

The effect of vaccination on milk production was evaluated in vaccinated and control cows experimentally challenged in two of four quarters with live Mycoplasma bovis. During the first three weeks after experimental challenge, six of eight unchallenged quarters on vaccinated cows and seven of eight unchallenged quarters on control cows became infected. Most of these quarters secreted normal milk, with negative California Mastitis Test scores and maintained normal milk production throughout most of the study (although some quarters on control cows remained infected). All challenged quarters became infected, had strong California Mastitis Test reactions, and had a drastic (greater than 85%) loss in milk production. Thereafter, four of eight challenged quarters on control cows remained infected, had mostly positive California Mastitis Test scores, produced mostly normal-appearing milk, and recovered some productive capabilities. By the end of the study no M. bovis could be recovered from challenged quarters on vaccinated cows and the milk appeared mostly normal. The California Mastitis Test scores on these quarters, however, remained elevated and milk production remained very low.     

Ostertagia ostertagi antibodies in milk samples: Relationships with herd management and milk production parameters in two Mediterranean production systems of Spain

The present study analyzed Ostertagia ostertagi antibodies by indirect ELISA in milk samples in two cattle systems in Mediterranean Spain to indirectly monitor gastrointestinal nematode (GI) parasitism effects on production. Individual samples from 10 animals and the corresponding milk herd samples were collected from 133 herds in Girona (intensive management) and 123 herds in Minorca (extensive management). Both locations showed high and significant positive relationships between average optical density ratios (ODR) of individual animals and ODR in their milk tank. Although antibodies levels were low, there were significantly higher in Minorca. Negative correlations between ODR values and milk production were found in both systems. Importantly, in Minorca, average herd milk production was higher in the herds that treated their animals against GI nematodes compared to those that did not treat. The ELISA technique was valuable to indirectly assess differences in the level of GI nematode infection even in cattle production systems with low levels of infection.     

Natural plant toxicants in milk: a review

Elimination of plant toxicants via milk by lactating animals is considered a minor route of excretion; however, it may be important when the health of the neonate or food safety in humans is considered. Among plant toxicants excreted in milk is tremetol or tremetone, the toxin in white snakeroot (Eupatorium rugosum) and rayless goldenrod (Haplopappus heterophyllus). These plants have been responsible for intoxication of cows and their suckling calves and for many human poisonings. Other plant toxins excreted through the milk that pose a toxicity hazard include pyrrolizidine alkaloids in Senecio, Crotalaria, Heliotropium, Echium, Amsinckia, Symphytum (comfrey), Cynoglossum (hounds tongue) and Festuca (tall fescue); piperidine alkaloids in Conium, tobacco and others; quinolizidine alkaloids in Lupinus; sesquiterpene lactones of bitterweed and rubber weed; and glucosinolates in Amoracia (horseradish), Brassica (cabbage, broccoli, etc.), Limnanthes (meadowfoam), Nasturtium (watercress), Raphanus (radish) and Thlaspi (stinkweed). Many plants such as Astragalus, Oonopsis, Stanleya, Xylorrhiza, Aster, Atriplex, Sideranthus and Machaeranthera accumulate selenium and may cause intoxication when grazed. Selenium is found in the milk at concentrations relative to the amounts ingested by the lactating animal. Excretion of selenium via the milk is important in the deficiency state, but when in excess it may cause toxicity to offspring.     

Tropical animal health and production

Summary Male mice inoculated withTrypanosoma (Trypanozoon) brucei of virulent type ETat 5, were subjected to pronounced social interaction and resultant stress by being grouped with stranger mice for 3 hours each day during the development of the infection. Three experiments were conducted and in each of these the stressed mice survived for a significantly longer period than did similarly infected control mice kept in singled isolation. One mouse survived the infection for 12 days during which time no antigenic variation was detectable by agglutination test in the infecting organism. The results establish the fact that social grouping can influence the survival time of mice to trypanosome infections. It is postulated that these results may have been due to a reduced immune response in the stressed mice which, in its turn, caused a delay in the release of harmful products of the antibodytrypanosome reaction.

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Resumen Ratones machos infectados conTrypanosoma brucei (Trypanozoon) del tipo virulento E.T.a.t. 5 fueron sometidos a interacción social y la tensión social consecuente por ser agrupados con ratones más fuertes durante 3 horas por día, durante el desarrollo de la infección. Tres experimentos se llevaron a cabo y en cada uno de éstos los ratones que habían sido sometidos a tensión sobrevivieron por más tiempo que aquellos infectados similarmente pero mantenidos aislados. Un ratón sobrevivió a la infección por 12 dias durante los cuales no se detectó ninguna variación antigénica en el organismo infectante por medio de la prueba de la aglutinación. Los resultados prueban que el agrupamiento social puede alterar el tiempo de sobreviviencia de ratones con infecciónes de tripanosoma. Se postula que los resultados se pueden deber a que los ratones bajo tensión tuvieron una respuesta inmune reducida lo cual causó un retraso en la liberación de productos tóxicos de la reacción entre los anticuerpos y el trypanosoma.

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Résumé Des souris males inoculées avec une souche virulente deTrypanosoma (Trypanozoon) brucei (Etat 5) furent soumises à un facteur d’agression d’ordre social résultant de leur cohabitation avec des souris étrangères à raison de 3 heures par jour pendant le développement de l’infection. Trois expériences furent conduites ainsi et dans chacune d’elles les souris soumises au ‘stress’ ont survécu de fa?on significative pendant une période plus longue que les souris témoins conservées isolées. Une souris a survécu à l’infection pendant 12 jours, période pendant laquelle aucune variation antigénique du trypanosome infectant n’a pu être décelée par le moyen de l’agglutination. Les résultats montrent que le groupage des souris peut influencer leur temps de survie aux infections à trypanosomes. On postule que ces résultats peuvent être dus à une réponse immunologique réduite chez les souris soumises au ‘stress’, ce qui provoque un retard dans le relargage des produits nocifs issus de la réaction anticorps-trypanosome.

     

Developing new veterinary services in milk quality: a review of a recent mastitis risk management co-development in Australia

A new veterinary service to promote ongoing, incremental improvements in the risk management of mastitis and milk quality was developed between 2005 and 2008. This was designed to enhance the relationship between the farmer and advisor, as an extension of the Countdown Downunder programme, Australia's national mastitis and milk quality programme. This service was co-developed between the Countdown Downunder programme team and a core development group of veterinarians involved with trialling the service, and farmers and social researchers. The service, known as Countdown MAX, involved advisory input at the planning stage, a written risk management plan, multiple engagements between the farm team and advisor for tracking and re-planning, and a service fee. Risk management resources (modules) were developed to be employed at the drying-off and calving periods, and during lactation. During the development and implementation phase eight veterinary practices conducted Countdown MAX consultations on 55 farms. Eighty-eight Countdown MAX modules were delivered in total, with 55% of farms completing more than one module but only 38% of modules reviewed successfully. A social research project examined the implementation of the Countdown MAX service in participating veterinary practices during the development phase. Findings of the project were that the successful uptake of a new mastitis service into a veterinary practice was enhanced through uptake by practice owners of the concept, the formation of a written practice plan, adequate communication and explanation of the new service to all staff, logistical support for the service within the practice, and transfer of mastitis expertise within the practice.     

乳牛日粮中添加大蒜素对乳品质和产奶率的效果观察

本文研究了乳牛日粮中添加大蒜素对乳品质和产奶率的影响,结果显示,乳牛日粮中添加80 mg/kg大蒜素对产奶量和乳脂率有显著的改善作用,平均产奶量比对照组提高2.145 kg/(d·头),乳脂率提高0.151%.添加量为80 mg/kg时乳牛产奶量和乳脂率提高幅度最大,由此确定大蒜素最佳使用量为80 mg/kg.     

Egg production and quality under three housing systems in the tropics

The aim of this study was to evaluate egg production and quality of Rhode Island Red (RIR) laying hens in an outdoor system in the subhumid tropic. Eighty RIR laying hens were measured in two periods and housed randomly under three treatments: outdoor (O), indoor (I) and in conventional cages (C). Egg weight (55.88, 53.76 and 57.16 g, for O, I and C, respectively), food intake/hen/day (138.94, 129.74 and 162.90 g, for O, I and C, respectively) and food efficiency (3.13, 3.22 and 3.96 for O, I and C, respectively) were significantly (P < 0.05) influenced by housing system; however, both egg production and final body weight were not different (P > 0.05). Yolk colour (10.76, 9.94 and 10.08 colour scale, for O, I and C, respectively), albumen weight (92.63, 92.28 and 90.08 g, for O, I and C, respectively) and yolk weight (15.19, 14.61, 15.48 g for O, I and C, respectively) were significantly (P < 0.05) influenced by housing system, but albumen height, Haugh units and egg shell weight remained similar (P > 0.05). Under the conditions of this study, outdoor egg production seems to be a sustainable system comparable to the commercial type based on wired cages.     

Effects of dry period length on milk production, health, fertility, and quality of colostrum in dairy cows. Invited review

In terms of milk production, the dry period (DP) is a non-productive time. In addition, the risk of mastitis increases when cows with daily milk yield >12.5kg are dried off, which is often the case when the DP is set to 55-60 days. References on the positive effects of a shortened DP on the metabolic health at the start of lactation and the subsequent reproductive performance were the motive of this review. Completely foregoing or shortening the DP produces a decrease in milk yield during the following lactation. This decrease is particularly pronounced for cows at the beginning of the second lactation. It is thought that this may be due in part to different involution and proliferation processes of the mammary glands in primiparous and multiparous animals. The majority of the scientific papers suggest that shortening the DP has a positive rather than a negative effect on udder health. The quality of the colostrum is also unaffected; but if there is no drying off, the colostrum will be diluted. When considered overall, the literature, with support from metabolic profile studies, appears to favour a reduced impact on energy metabolism in early lactation in circumstances when the DP is shortened or waived. Clear positive effects on parameters relevant to energy metabolism however only apply to multiparous animals, and other factors, such as milking frequency before and after calving, exert an influence. Positive effects of shortening the DP on the reproductive performance were shown in several studies. Time from calving to first ovulation as well as indicators for assessing the success of artificial insemination and reproductive performance showed better results in animals with no or shortened drying off periods. Again, this only applied to multiparous animals. Overall, there is no single clear answer to the question of an optimal length of the DP, but conversely it is abundantly clear that a dry period of 55-60 days is not necessary in all cases and does not make sense under certain circumstances. Based on the study findings from recent years, the determination of dry periods should be used as a farm-specific and needs-oriented applied management decision.