1Khwairakpam Ratika, 2Kshetrimayum Mahesh Singh and 3R.K. James Singh,1,2College of Veterinary Sciences and Animal Husbandry, CAU(I), Jalukie, Nagaland
3Indian Verterinary Reserach Institute, Izatnagar, Bareilly
Cows yielding more than 20 kg/day and buffaloes yielding more than 15 kg per day are high yielding animals. The milk production in high yielders (producing above 15 kg of milk/day) in the first six weeks of lactation, is so high that the secretion of nutrients into the milk exceeds the rate of uptake of nutrients from the digestive tract. High energy requirement for milk production combined with low feed intake can result in an energy deficit or negative energy balance. A severe negative energy balance is related to an increased risk of metabolic disorders and diseases like fatty liver and ketosis. The nutrient deficit is compensated by the diversion of nutrients from the body reserves (mobilisation of body fat and protein) resulting in weight loss. Too much loss in body weight can prove harmful and uneconomical. The appetite of the animal during the early lactation (upto 8 weeks) is reduced by 2 to 3 kg per day. So all the nutrients needs of the animal are to be provided within this appetite limit. It is difficult to meet the nutrient requirements, particularly the energy requirement of such high yielders (more than 15 kg of milk production per day in cows and 12 kg milk yield per day in buffaloes) through normal concentrate mixture and fodder. High energy diets are to be formulated and challenge feeding has to be adopted. Adequate fibre (36% NDF in the total ration) is critical for maintenance of normal milk fat. Usually, all such cows and buffaloes will remain under negative energy balance during first 5 months of lactation.
Nutrient requirements vary with the stage of lactation and gestation. Five distinct feeding phases can be defined to attain optimum production, reproduction and health of dairy cows
Phase 1: Early lactation—1 to 70 days (peak milk production) after calving (postpartum).
Phase 2: Peak DM intake—70 to 140 days (declining milk production) postpartum.
Phase 3: Mid- and late lactation—140 to 305 days (declining milk production) postpartum.
Phase 4: Dry period—60 to 14 days before the next lactation.
Phase 5: Transition or close-up period—14 days before to parturition.
Nutrient Requirements of High Yielding Dairy Cattle During Different Phases Of Lactation
a) Water requirements
- Lactating dairy cows need 60–70 litres of water each day for maintenance, plus an extra 4–5 litre for each litre of milk produced.
- Water requirements increase by 6 lts/day for every 4 0 C raise in air temperatures.
- Lactating cows will drink 150 to 200 litres of water per day in the summer months
b) Crude protein requirements
|Stage of lactation
|% CP in the ration
|16 – 18 %
|14 – 16 %
|12 – 14 %
|10 – 12 %
Undegradable or bypass protein (UIP) should be 35 to 40 percent of the CP in early lactation and 30 to 35 percent of CP in late lactation.
Requirements for metabolizable methionine and lysine should also be considered as these are the limiting amino acids for milk production
(c) Roughages: Roughage quality is partly determined by fibre levels. Complete feed of high yielding cow should not contain less than 21% ADF or 28% NDF. More than 80% fibre should come from lush green forage or good quality silage and remaining from quality hay or naturally fermented straw. The recommended roughage to concentrate ratio for high producing cows should be 50: 50, 60:40 and 75:25 in early, mid and late lactation
(d) Fat: Fat plays important role in performance of lactating animals. The BIS specifications have recommended only 3.0 % and 2.5% fat, in type I and type II concentrate mixture, respectively. Whereas NRC feeding standard have recommended 3.0 % fat, in the complete feed for dairy cattle. However, recent reports indicate that dietary fat upto 5% (complete feed) have direct positive impact on the quantity as well quality of milk.
(e) Salt: 0.5 percent of the ration DM or 1 percent of the concentrate mixture.
(f) Urea • 3 % of concentrate mixture or 1 percent of the total dry matter intake.
• Ration form: Avoid too fine chopping of forages and concentrates
Minerals and vitamins:
Calcium is one of the most crucial elements in the ration to be considered more carefully. At the beginning of the lactation, the demand of calcium for milk production increases dramatically, leading to the fall in blood calcium levels. This stimulates the secretion of parathyroid hormone (PTH) from parathyroid glands, resulting in activation of Vitamin D3, which increases the absorption of Ca from intestine and mobilization of bone calcium. But this whole process requires 24- 48 hours, and can’t prevent animals from milk fever as more than 60% cases of milk fever occur within 24 hr of parturition. To avoid incidences of milk fever, the best feeding management practice is to provide low Ca (<50g/d) diet during the dry period (last 2-3 weeks of gestation) which should be increased to 100g/d, at least 2 days before parturition. The diet after parturition should have sufficient Mg, essential for conversion of Vit D3 to 25 H D3 in liver.
Selenium and Vit E play an important role in lactating cows. Both help to maintain the immune system and reproductive efficiency of the animal. The recommended dose is 0.4- 06 g/ day Vit E and 0.3 ppm selenium/ day. Niacin (Vit B complex) being synthesized in the rumen is inadequate for high yielder. It stimulate feed intake, prevent ketosis and improves milk production and increased milk fat content. The recommended dose is 6g/cow/ day.
The diet of high yielding cow contains more than 50% concentrate mixture, which results in less salivation and rumen buffering. The easily fermentable grain based concentrate, lead to increased acid production resulting in decreased rumen pH, reduced fibre digestion, depressed feed efficiency and low milk fat percentage. Addition of dietary buffers @1.5% in high concentrate ration can neutralize the acidity in rumen.
Dietary cation anion balance:
Dietary cation anion difference (DCAD) or balance can be used to alter the metabolic status of both dry and lactating cows. DCAD is calculated by subtracting the milliequivalents of positively charged cations, sodium and potassium, from the negatively charged anions, sulfur and chlorine. If more milliequivalents of cations are available, then the charge is positive and if more anions are present then the charge is negative. Dry cows can benefit from low DCAD resulting in improved in improved bone calcium mobilization and lactating cows benefit from positive DCAD that buffers acids produced during ruminal digestion.
The term “Bypass Nutrient” refers to that fraction of the nutrients which gets fermented in the rumen to a comparatively low degree. It then becomes available at the lower part of the gastro-intestinal tract in the intact form for subsequent digestion and absorption. Examples of bypass nutrients include; protected proteins/amino acids, protected fat, protected starch and chelated minerals and vitamins. Protein that is not degraded in the rumen and reaches the small intestine unmodified is called rumen bypass protein. Supplementation of this type of protein can improve productivity in terms of improved efficiency of meat, milk and wool production. Various methods have been used for protecting proteins from rumen degradation, such as heat treatment and formaldehyde treatment. Supplementation of bypass fat in the diet of animals has proven very useful to increase milk yield, FCM yield, efficiency of nutrient utilization, postpartum recovery of the body weight, body condition score, reproductive performance and alleviate problems of negative energy balance without adversely affecting the dry matter intake and rumen fermentation.
Challenge feeding means the cow with potential of high milk production are to be fed increase amount of concentrate to challenge them to produce to the maximum. Challenge feeding starts two weeks before the expected date of calving. This challenge feeding will condition her digestive system for the increased quantity of feed to provide sufficient nutrient to initiate lactation on the higher plane. Generally, the animals are started with 1.5 to 2.0 kg concentrate mixture (@0.3 to 0.5% of body weight) on the date 2 weeks before calving followed by an increment of 0.3 to 0.5 kg daily, so that they will be receiving about 1 kg concentrate mixture per 100 kg body weight at calving. This is practice to challenge the cow to reach her maximum milk production potential.
Feeding management tips:
- Feed the cow in several small meals rather than two large ones especially in hot weather.
- Have fresh feeds available in mangers after milking.
- Allow cow access to feed for at least 22 hours of the day.
- Purchase high quality feed ingredients, must get them analysed periodically.
- Minimize drastic changes in the ration.
- Offer minimum mineral mixture before parturition but increase it significantly immediately after parturition.
- Stop milking at least 60 days prior to parturition.