Tag: "protein"

  • There is evidence that alpacas derive most of their glucose for energy from the deamination of amino acids. Consequently, they may have an insufficient supply of amino acids to meet their requirements for fibre growth. To optimise fibre production, it may be necessary to supply alpacas with supplemental protein to meet their requirement for extra amino acids. In this study, we examined if the proportion of rumen-degradable dietary protein (RDP) to undegradable dietary protein (UDP) from canola meal influenced the fibre growth of alpacas. We hypothesised that alpacas fed at maintenance a diet containing canola meal protein high in UDP would produce more fibre and spend less time urinating than peers fed a similar amount of canola meal protein with a low proportion of UDP. Four groups of eight alpacas were fed diets with the following ratios of UDP : RDP: 0 : 100, 30 : 70, 60 : 40 or 100 : 0 from canola meal protein. The fibre growth of the animals was measured over 2 months and the behaviour of the animals in the two extreme groups (0 and 100% UDP) was measured over 5 days. The alpacas fed the 0% UDP diet produced fibre of finer diameter than the alpacas fed diets containing higher levels of UDP (P = 0.039) and the 0% UDP group also spent more time urinating (P = 0.027). This result suggests that alpacas may have a limited ability to recycle nitrogen to the fermentative chambers of their stomach when fed a diet low in UDP. Consequently, microbial protein synthesis in the fermentative chambers may have limited the supply of amino acids available to the alpacas. more »
  • Alpacas are unique animals in terms of their digestive capabilities and energy and protein metabolism. Nutritional information pertaining to alpacas has been extrapolated from data based on true ruminant nutritional requirements and is therefore inaccurate and misleading for alpaca producers. The general hypothesis tested in this thesis was that alpacas would be better at utilising feedstuffs and be more efficient at obtaining glucose and amino acids that are essential for both maintenance and fibre production than sheep. Two experiments in this thesis (Chapters 3 and 5) evaluated the potential of using undegradable dietary protein (UDP) in alpaca diets as a means of optimising fibre growth. Chapter 4 of this thesis reports a training method and the design of a special metabolism pen for alpacas which was developed to conduct the experiments described in Chapters 5 and 7. The next experiment (Chapter 6) determined whether alpacas could utilise calcium propionate as a source of glucose. The last experiment (Chapter 7) examined how intakes of different proportions of energy and protein influenced nitrogen metabolism in alpacas compared to sheep. The hypothesis tested in Chapter 3 was that alpacas fed a diet containing canola meal high in UDP to meet maintenance requirements would produce more fibre and spend less time urinating than peers fed a similar amount of canola meal with a low proportion as UDP. Alpacas were fed diets of similar metabolisable energy (ME) content at a level calculated to maintain body weight with the following ratios of UDP: rumen degradable dietary protein (RDP); 0:100 (0% UDP), 30:70 (30% UDP), 60:40 (60% UDP) or 100:0 (100% UDP) from canola meal protein. The fibre characteristics of the alpacas were analysed to determine whether fibre production was affected by the different proportions of UDP in the diet. The behaviour of the alpacas in the 100% and 0% UDP protein groups was also monitored. The alpacas fed the 0% UDP diet produced fibre of finer diameter than the alpacas fed diets containing higher levels of UDP, but the 0% UDP group spent more time urinating. This suggests that when fed RDP, which should increase the ammonia concentration in the fermentative organs, the excess ammonia is converted to urea in the liver and excreted in urine. Thus the proportion of dietary protein as RDP may influence the pathways of nitrogen metabolism in alpacas. In light of the results from Chapter 3, the experiment in Chapter 5 aimed to determine if protein degradability influenced nitrogen retention or energy balance and whether alpacas utilise nitrogen more efficiently than sheep. It was hypothesised that alpacas fed a diet containing RDP in the form of canola meal would excrete more nitrogen than those fed UDP and, that alpacas fed the same diet as sheep at maintenance would retain more nitrogen. Alpacas and sheep were fed the same diets as used in the experiment for Chapter 3 while they were housed in metabolism pens. Nitrogen and energy balances were measured to determine whether alpacas metabolised nitrogen more efficiently than sheep and whether protein degradability influenced the ability of alpacas to retain nitrogen. The degradability of the protein in the diet did not influence the amount of nitrogen retained in either species and both the sheep and the alpacas retained similar amounts of nitrogen. However, the alpacas tended to retain less nitrogen as a percentage of the nitrogen absorbed from their food than did sheep fed the same diet. The results suggested that sheep and alpacas probably obtain their energy from different components of their food and utilise protein in different ways. In Chapter 6, the ability of alpacas to spare amino acids for fibre growth by utilising a gluconeogenic precursor was determined. It was hypothesised that alpacas supplemented with calcium propionate would produce more fine fibre than un-supplemented animals. Although the diets supplemented with calcium propionate should have provided more energy, the ME intake of all animals was similar. It appears that rather than sparing amino acids, the alpacas regulated their energy intake by refusing to consume additional energy as calcium propionate. Whether alpacas do moderate their energy intake and prefer to utilise protein as their source of glucose for maintenance was examined in Chapter 7. It was hypothesised that irrespective of their energy intake, alpacas would progressively retain more nitrogen as their intake of dietary protein increased. Conversely, it was expected that sheep would retain less nitrogen than alpacas when their intake of dietary protein increased because they rely on gluconeogenic precursors such as propionate, rather than protein, to meet their energy requirement. The alpacas responded to the dietary treatments in a similar manner to sheep by retaining a similar proportion of the dietary nitrogen that they absorbed. However, there was a trend for the alpacas to retain more of the absorbed nitrogen than the sheep when fed a diet that provided almost twice their maintenance requirement of protein. There was some evidence to suggest that alpacas do not regulate their protein intake as they appear to do with their energy intake. The results from these studies have shown that alpacas obtain glucose for energy predominantly from the protein component of their diet as part of an adaptation to the harsh conditions of their native environment. Our understanding of the ability of alpacas to metabolise energy and nitrogen, compared to sheep, will enable producers to be informed of appropriate ways in which to feed their animals to promote productive and reproductive efficiency. more »