| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Eriksson, Susanne, et al.
(författare)
-
Invited review: Breeding and ethical perspectives on genetically modified and genome edited cattle
- 2018
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 101, s. 1-17
-
Forskningsöversikt (refereegranskat)abstract
- The hot topic of genetic modification and genome editing is sometimes presented as a rapid solution to various problems in the field of animal breeding and genetics. These technologies hold potential for future use in agriculture but we need to be aware of difficulties in large-scale application and integration in breeding schemes. In this review, we discuss applications of both classical genetic modifications (GM) using vectors and genome editing in dairy cattle breeding. We use an interdisciplinary approach considering both ethical and animal breeding perspectives. Decisions on how to make use of these techniques need to be made based not only on what is possible, but on what is reasonable to do. Principles of animal integrity, naturalness, risk perception, and animal welfare issues are examples of ethically relevant factors to consider. These factors also influence public perception and decisions about regulations by authorities. We need to acknowledge that we lack complete understanding of the genetic background of complex traits. It may be difficult, therefore, to predict the full effect of certain modifications in large-scale breeding programs. We present 2 potential applications: genome editing to dispense with dehorning, and insertion of human genes in bovine genomes to improve udder health as an example of classical GM. Both of these cases could be seen as beneficial for animal welfare but they differ in other aspects. In the former case, a genetic variant already present within the species is introduced, whereas in the latter case, transgenic animals are generated-this difference may influence how society regards the applications. We underline that the use of GM, as well as genome editing, of farm animals such as cattle is not independent of the context, and should be considered as part of an entire process, including, for example, the assisted reproduction technology that needs to be used. We propose that breeding organizations and breeding companies should take an active role in ethical discussions about the use of these techniques and thereby signal to society that these questions are being responsibly addressed.
|
|
| 8. |
|
|
| 9. |
- Hernandez, Carlos, et al.
(författare)
-
Colostrum feeding routines - Passive immunity and welfare in dairy calves
- 2015
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Calves are born with insufficient immunity to fight disease and rely on the passive transfer of immunity via ingestion of maternal immunoglobulins (IG) present in the colostrum. To ensure adequate transfer of immunity, dairy farmers utilize different methods to feed colostrum to their calves. Feeding methods include bottle or bucket feeding, oesophageal tube (OT) feeding, or suckling the dam. However, inherent differences between the feeding methods are known to result in different levels of transfer of passive immunity to the calves. These differences are related to the ability to control 1) the timing of first colostrum feeding, 2) the quality of the colostrum (mainly IgG content) and 3) the volume of colostrum consumed by the calves. With OT feeding it is easy to control the timing, quality and volume. With bottle or bucket feeding it is easy to control the timing and quality but more difficult to control the volume of colostrum consumed by the calves. In suckled calves, it is more difficult to control all, the timing, quality and volume of the colostrum consumed. Because OT feeding makes it possible to control the three main factors affecting transfer of passive immunity, farms that feed colostrum via OT have less failure of passive transfer (FPT) of immunity (often defined as serum IgG1 concentrations of <10 mg/ml at 24 h of age) than farms that bottle feed or allow the calves to suckle their dams. While the presence of the dam and suckling has been shown to increase absorption of immunoglobulins in dairy calves, several studies have found that dairy farms that allow the calves to obtain their first colostrum by suckling their mothers are at increased risk of FPT of immunity. Similarly, a study of Swedish dairy farms found an increased risk of severe diarrhoea in farms where calves were allowed to suckle compared to farms where the farmer fed their calves their first meal. The discrepancy between increased rate of absorption in suckled calves and increased FPT of immunity is likely due to the low volume of colostrum that the calves voluntarily consume during the first 24 h and a delayed ingestion of their first colostrum that outweighs any improvement in the rate of absorption. For these reasons, some dairy farms in North America feed first colostrum via OT as a way to ensure a good transfer of passive immunity in dairy calves, and now this practice is also being promoted in Sweden. While the OT feeding method seems ideal from the transfer of passive immunity point of view, it is not without risks and could compromise the welfare of the new born calf. Oesophageal tube feeding is an invasive procedure that requires trained personnel in order to prevent injury and prevent colostrum entering the respiratory tract, which could lead to pneumonia and in extreme cases death. In addition, force feeding strong and healthy calves with an OT, as opposed to intubating only weak, anorexic/dehydrated calves, could result in calves that resist and struggle excessively in response to the intubation procedure increasing the risk of injury, discomfort and distress. Furthermore, due to the large variation in colostrum quality (IgG content), it is often recommended to feed 3-4 L of colostrum or 10 % of the calf's body weight in the first meal to ensure adequate passive transfer of immunity. These large amounts of colostrum far exceed the abomasum capacity of the average new born calf (approx. 2 L for a 35 kg calf) and exceeds the amount of colostrum that calves voluntarily consume in the first 24 h after birth (2.4 ± 1.5 L). In addition, oesophageal tube feeding does not stimulate the oesophageal groove reflex, which directs the colostrum from the oesophagus to the abomasum where the necessary enzymes for digestion are found. Force feeding large volumes of colostrum in a short period of time to new born calves, such as during OT feeding, could lead to unnecessary discomfort and stress, but this has not been studied yet. While most studies have focused on the effects of OT feeding on transfer of passive immunity, health outcomes and mortality rates, there is no scientific evidence about the consequences of OT colostrum feeding for the behaviour and welfare of dairy calves. For this reason, a large multidisciplinary project is currently being carried out at the Department of Animal Nutrition and Management at SLU. ) aimed at addressing some of the issues concerning the routine use of OT feeding. The project aims to investigate the effects of OT vs suckling vs bottle colostrum feeding at birth, on the transfer of passive immunity, physiological, endocrine and behavioural response to the three feeding methods, growth, health, development of gut microbiota and welfare in dairy calves. In addition, the public's perception of oesophageal tube feeding as a routine management for colostrum feeding in dairy calves will be investigated. Further research on calves and colostrum management at our department include a study by PhD student Lisa Andree O´Hara comparing the use of refractometer (% Brix) and colostrometer as estimators of IgG content in milk (supervisor: Kjell Holtenius) and the PhD project of Bui Phan Thu Hang aimed at improving calf performance in small-scale dairy production in Southern Vietnam (supervisors: Kerstin Svennersten, Ewa Wredle, Johan Dicksved and Duong Nguyen Khang).
|
|
| 10. |
|
|
