Cows averaged 4. Lameness reduced eating time: non-lame cows ate for 4. Cows spending more time milking spent less time feeding. First-lactation heifers spent about 25 more minutes eating compared with cows in their third or later lactation. Other researchers have found first-lactation heifers have a slower feeding rate and take more meals in a day than older cows. Standing in alleys averaged 2. This time included moving between feeding and resting areas, socializing and drinking. Actual time drinking appeared to take only five to seven minutes per day.
During periods of heat stress, cows often increase standing time standing in alleys near fans to cool off. The Wisconsin study was completed when daily temperatures averaged less than Non-lame cows had an average standing time of 2. Gomez and Cook theorized reduced time standing for lame cows resulted from either trying to avoid aggressive, dominant cows or shifting their standing location to the stalls from alleys.
Cows had a median time of 2. They spent less time standing in stalls when higher pen-stocking density limited stall access. This suggested cows value stall occupancy as a resource. Older cows stood longer in the stalls than first-calf heifers. This probably resulted from heifers spending more time feeding and experiencing fewer foot problems than older cows.
Other researchers have offered two different theories for longer standing times on mattresses. Some have suggested cows simply prefer to stand on mattresses instead of the concrete alleys, while other researchers have theorized this behaviour results from the animals having greater difficulty rising from and lying on mattresses compared with sand bedding. Standing time in mattress barns increased with lameness. The authors theorized this may be caused by the cushion, traction and support sand bedding offers during the rising and lying movements of lame cows in comparison to the flat, firm surface of a mattress.
The cows studied averaged Similar to humans, cows need to be pregnant and give birth for milk production and release to occur.
Milk production involves the complex interaction of a number of different hormones, which are set into play during pregnancy. Typically, during the second and third trimesters of pregnancy various hormones, such as progesterone and oestrogen are produced, which stimulate the growth and development of the milk duct system within the udder. Oxytocin is another important hormone which allows the secretion of the milk to occur - also known as milk 'let down'.
Prolactin a protein levels are stimulated when the udder is suckled by the calf or milked by the milking machine and this needs to occur for milk production to continue. Lactation persistencies of less than 8 per cent per month may be achievable in tropical dairy feedlots but more realistic persistencies are the 8 to 12 per cent per month presented in the Table 1 and Figure 2.
Virtually every small holder farmer records daily milk yield of his or her cows, so they know peak yield and can easily determine the monthly rate of decline, providing a simple monitoring tool to assess their level of feeding management. Unless feeding management can be improved, it may be better in the long run to import cows of lower genetic merit. From Table 1, such cows would produce similar milk yields if they could be fed to 8 per cent per month milk persistency and they are more likely to cycle earlier.
Lactation anoestrus can occur as the cows are forced to utilise more of their body reserves in early lactation. This can lead to low peak milk yields and shortened lactation lengths. Cows will dry off prematurely if they receive insufficient feed nutrients to maintain viable processes of milk production in their mammary tissue.
The impact of decreasing lactation lengths on day lactation milk yields and average daily milk yields are presented in Table 2. These data are based on the same persistency data used in Table 1. The penalties for these shortened lactation lengths are presented in Table 3.
Compared to 10 month lactations, inherently poor yielding cows with low peak milk yields can lose 20 to L milk through only 9 months milking or 90 to L milk if only milking for 8 months. Following higher peak milk yields, this will increase to penalties of 30 to L milk for 9 month to to L for 8 month lactation lengths.
These tables are based on day lactation lengths, that is under an ideal situation where cows calve down every 12 months. Inter-calving intervals are more likely to be 13, 14 or 15 months, hence lactation lengths should be even longer than days. Ideally cows should be managed to have a two month dry period to allow the mammary tissue to recuperate before the next lactation.
However, lactation lengths of just 8 months followed by dry periods of another 8 months are all too common in many tropical small holder dairy farms.
This then equates to only 50 per cent of the adult cows milking at any one time. After milking, the teat sphincter muscle takes 30 minutes to close. It also takes 30 minutes for the post-dip to dry.
If a cow lies down while the sphincter is still relaxed or before the teat dip has dried, it can lead to bacteria entering the teat and potential infection.
It is estimated that 50 percent of new contagious mastitis infections can be prevented by complete and consistent post-milking teat dipping and allowing the dip to dry. A good way to keep cows standing for at least 30 minutes after milking to provide fresh feed or push feed up so the cows are motivated to stand and eat after milking. All rights reserved.
0コメント