Birgitta Johansson

Effect of suckling on the release of oxytocin, prolactin, cortisol, gastrin, cholecystokinin, somatostatin and insulin in dairy cows and their calves.

The aim of the present study was to examine how different types of early interaction between dairy cows and their calves influence milking/suckling-related hormone release in the cows and sucking/bucket-drinking related hormone release in calves. Eighteen cows of the Swedish Red and White breed were studied during the first week after parturition. The cows were machine milked twice daily, and allotted to one of three treatments: [1] cow and calf were kept together and the cow was allowed to suckle the calf for 30 min about 1 h before each milking; [2] cow and calf were kept together and the calf was bucket fed twice daily; and [3] cow and calf were separated immediately after parturition, and the calf was kept in a single box and was bucket fed twice daily. Blood samples were collected around day 7 from both cows and calves. The plasma levels of oxytocin, prolactin, cortisol, gastrin, cholecystokinin (CCK), somatostatin and insulin were analysed. In the cows the levels of oxytocin, prolactin and cortisol were influenced by all three treatments, except for the level of cortisol which did not respond to suckling. The main finding was that the release of oxytocin was as significantly greater during suckling compared with machine milking. In the calves, the hormone levels were also influenced by the different milk feeding routines. The plasma concentrations of oxytocin, gastrin, CCK and insulin increased in response to milk ingestion in all treatments. However, during sucking, the increase of oxytocin was significantly greater than during bucket drinking. In addition, a strong correlation between oxytocin and insulin was found in response to sucking. Further, significant increases in prolactin and somatostatin, and a decrease in cortisol were found during sucking. The level of somatostatin also increased in response to bucket feeding when calves were kept separately. During bucket feeding, no significant correlation was found with oxytocin, but strong correlations between the gastrointestinal hormones gastrin, CCK, somatostatin and insulin were seen. Together these data suggest that different hormonal patterns were triggered in the cows by suckling and milking and in the calves by sucking and bucket drinking. This is further supported by different correlation patterns observed in the calves in response to sucking and bucket feeding. The present findings imply that management routines for cows and calves during the first week after parturition have consequences for the physiology of the animals.

Oxytocin facilitates behavioural, metabolic and physiological adaptations during lactation

The aim of this article is to propose that oxytocin not only stimulates milk let down, but also adapts behaviour and physiology to facilitate lactation in mammals including dairy cattle. Circulating oxytocin as well as neurogenic oxytocin participates in these regulatory processes. In short, oxytocin stimulates maternal interaction and attachment between mother and young. It also participates in the metabolic prerequisites for milk production by e.g. stimulating glucagon release and thereby, mobilisation of glucose. Digestive and anabolic aspects of metabolism are also stimulated, e.g. by increased vagal nerve activity. Adaptations consistent with an antistress like pattern are also induced. Cortisol levels are decreased as well as blood pressure, and behaviours characterised by calm, reduced levels of anxiety and more social activity are promoted. These effects seem to be present in monogastric animals as well as in ruminants. The expression of various aspects of these adaptations vary according to the special needs and living environmental circumstances of different species. The mechanisms behind the effect spectrum of oxytocin are being explored in other experimental models. A second aim of this paper is to suggest that efficiency of lactation can be promoted by facilitating oxytocin release in connection with milking by enhancing the amount of sensory stimulation.

Supplementing dairy steers and organically managed dairy cows with synthetic vitamin D3 is unnecessary at pasture during exposure to summer sunlight.

Use of synthetic feed additives, including synthetic vitamin D3 (D3) in the feed for cows and other ruminants, is not consistent with the international principles of organic farming. If dairy farmers wish to produce in accordance with the organic principles, production animals would be left with only their endogenous production of D3 from summer sunlight as a source of D3. To examine the impact of supplemental synthetic D3 from the feed on the D3 status of dairy cattle in organic production in Nordic countries, 20 high-yielding dairy cows and 30 dairy steers were divided into two groups: one supplemented with synthetic D3 in the feed and one not supplemented with synthetic D3. Vitamin D3 status of the animals was assessed by measuring the concentration of the liver-derived 25-hydroxyvitamin D3 (25OHD3) in plasma. Results showed that 25OHD3 concentration in plasma from dairy cattle as well as from steers decreased during winter for both supplemented and unsupplemented groups. Unsupplemented cows and steers had approximately 2 ng 25OHD3 per ml plasma during winter, whereas supplemented animals had between 10 (cows) and 30 (steers) ng/ml. During summer and autumn there was no additive effect of supplementing with synthetic D3 since unsupplemented and supplemented animals had the same D3 status at this time of year. In all cows summer concentrations of 25OHD3 were 20-25 ng/ml and in all steers 40-50 ng/ml plasma. The decrease in vitamin D3 status during winter indicates that cows and steers are able to store D3 only to a limited extent. The results also show that cows or steers fed supplemental D3 according to Swedish recommendation throughout the year are not able to maintain their summer value of 25OHD3 during winter.

Effect of feeding before, during and after milking on milk production and the hormones oxytocin, prolactin, gastrin and somatostatin.

Feeding during milking has been shown to influence milk production, milk flow and milking time as well as the secretion of the pituitary hormones oxytocin and prolactin, and the gastrointestinal hormone somatostatin. However, it is not known whether feeding before or after milking has any effect. The aim of the present study was to investigate how the timing of feeding relative to milking influences milk production and flow, milking time and hormone secretion. The trial was carried out over 9 weeks with 24 cows at varying stages of lactation. Each treatment period lasted for 3 weeks, including one registration week. The cows were fed ad lib. and were exposed to three treatments: feeding 1.5 h before milking (FBM), feeding at exactly the same time as milking (FDM) and feeding 1.5 h after milking (FAM). The most marked treatment effect was observed during morning milking. FDM resulted in higher milk production and higher yields of protein and lactose. FAM produced a lower fat yield and a lower fat content compared with FDM, and a lower lactose content than either FBM and FDM. Milking time was longer when cows were fed during milking, but no significant effects on milk flow were found. The amount of milk collected during the first 2 min of milking was lower when cows were fed after milking. Milking-related oxytocin and somatostatin secretion was lower in FAM than in FDM. The level of prolactin was lower when cows were fed before or after than during milking. More studies are needed to elucidate whether there is a long-term effect on milk production related to the discussed milking routines.

Cold-pressed hempseed cake as a protein feed for growing cattle

Abstract Cold-pressed hempseed cake was investigated as a protein feed for young calves and finishing steers. Half of the animals were fed cold-pressed hempseed cake, whereas the other half were fed a mixture of soybean meal and barley. Effects on feed intake, liveweight gain (LWG), faecal traits and carcass traits (steers only) were studied. Neutral detergent fibre intake was higher for animals fed hempseed cake than for those fed soybean meal (P<0.05). In addition, the number of long particles in faeces was lower (P<0.05) and faecal dry matter content and consistency were higher from animals which were fed hempseed cake (P<0.05; steers only). Higher feed intakes in calves fed hempseed cake (P<0.05) combined with similar LWG resulted in lower feed efficiency in hemp-fed calves (P<0.05). In conclusion, hempseed cake compared to soybean meal as a protein feed for intensively fed growing cattle results in similar production and improved rumen function.

Performance of dairy cows fed an entirely organic diet containing cold-pressed rapeseed cake

Abstract Organic dairy production will be based entirely on organically grown feeds as of 2008, and thereby a demand is created to find suitable feeds that are possible to grow locally. The aim of this experiment was to investigate whether milk yield and milk composition were maintained when cows were fed a 100% organic diet, with around 15% of dietary DM from cold-pressed organic rapeseed cake, compared to a 95% organic diet, in which a conventional protein source was used. Two experimental groups included 20 cows each and the study was carried out during two indoor periods. For cows fed the rapeseed cake diet, milk yield increased by 3.0 kg/day, but contents of milk fat and milk protein of multiparous cows decreased, resulting in similar yields of energy-corrected milk in early lactation. Milk from cows fed rapeseed cake had increased content of unsaturated fatty acids, including conjugated linoleic acid. In conclusion, it is possible to maintain milk production of dairy cows fed 100% organic feedstuffs using cold-pressed rapeseed cake as the main protein source compared to a 95% organic ration.

Risks and opportunities of increasing yields in organic farming: a review

Current organic agriculture performs well in several sustainability domains, like animal welfare, farm profitability and low pesticide use, but yields are commonly lower than in conventional farming. There is now a re-vitalized interest in increasing yields in organic agriculture to provide more organic food for a growing, more affluent population and reduce negative impacts per unit produced. However, past yield increases have been accompanied by several negative side-effects. Here, we review risks and opportunities related to a broad range of sustainability domains associated with increasing yields in organic agriculture in the Northern European context. We identify increased N input, weed, disease and pest control, improved livestock feeding, breeding for higher yields and reduced losses as the main measures for yield increases. We review the implications of their implementation for biodiversity, greenhouse gas emissions, nutrient losses, soil fertility, animal health and welfare, human nutrition and health and farm profitability. Our findings from this first-of-its-kind integrated analysis reveal which strategies for increasing yields are unlikely to produce negative side-effects and therefore should be a high priority, and which strategies need to be implemented with great attention to trade-offs. For example, increased N inputs in cropping carry many risks and few opportunities, whereas there are many risk-free opportunities for improved pest control through the management of ecosystem services. For most yield increasing strategies, both risks and opportunities arise, and the actual effect depends on management including active mitigation of side-effects. Our review shows that, to be a driving force for increased food system sustainability, organic agriculture may need to reconsider certain fundamental principles. Novel plant nutrient sources, including increased nutrient recycling in society, and in some cases mineral nitrogen fertilisers from renewable sources, and truly alternative animal production systems may need to be developed and accepted.

Knowledge synthesis and dissemination in organic research in Sweden: integrating ethics

EPOK (Centre for Organic Food and Farming) at the Swedish University of Agricultural Sciences (SLU) works with knowledge synthesis, communication and research initiation in the field of organic farming. In order to facilitate the networking, researchers at departments of different scientific fields are associated to EPOK on a part-time basis. An important aspect of the knowledge transfer is to integrate the basic ethical concepts of health, ecology, fairness and care of organic farming according to the International Federation of Organic Agriculture Movements into the practical work. In the current EPOK activities the aim is to incorporate the principle of health in the work about animal nutrition and husbandry and in the synthesis work on nutritional aspects of organic food. The ecological principle is implemented in the work concerning cropping systems and interactions with soil fertility, the local flora and fauna and surrounding environment. The fairness principle influence the work on life cycle analysis of organic farming and its effect on climate change, as well as the efforts to give the animals possibility to natural behaviour. The care principle stresses the fact that the current agricultural practises must be developed and refined so that they support ecosystem services that promotes resilient production systems, which is exemplified by the work with biological crop protection methods. Our experience is that this approach to disseminating science to the society is fruitful. Through synthesizing research and experiences by system analysis of the food chain and its environmental impact the ethical principles can be emphasized in a scientific way. Other important activities are to organize workshops and to promote activities that increase the scientific knowledge relevant to organic farming. The approach of EPOK emphasizes the importance of communication through printed leaflets and reports, as well as, electronic newsletters and messages in social media. Furthermore, forums and platforms are created for an enhanced public dialogue.