Milk production from cows grazing on tropical grass pastures. 2. Effects of stocking rate and level of nitrogen fertilizer on milk yield and pasture-milk yield relationships

1985 ◽  
Vol 25 (3) ◽  
pp. 515 ◽  
Author(s):  
TM Davison ◽  
RT Cowan ◽  
RK Shepherd

The effects of stocking rate and rate of nitrogen fertilizer application on milk yield from a Gatton panic (Panicum maximum cv. Gatton) pasture were studied over 3 years at Kairi Research Station on the Atherton Tablelands. Thirty-two Friesian cows were used in a 4x2 factorial experiment with treatments 2.0,2.5,3.0 and 3.5 cows/ha, each at 200 and 400 kg N/ha.year. Fat-corrected milk (FCM) yield per cow decreased (P<0.05) with increasing stocking rate according to the equation (� s.e.): Y=3476-276 ( � 111) X (P<0.05), where Y is FCM yield per cow (kg), and X is the stocking rate (cows/ha). FCM yield per hectare increased linearly (Pt0.01) with increasing stocking rate in each year and was represented by the following equations ( � s.e.) for nitrogen applications of 200 and 400 kg/ha.year, respectively: Y = 1584 + 1967 (� 289) X Y = 2366 + 1967 (�289) X (P<0.01), and where Y is FCM yield per hectare (kg) and X is the stocking rate (cows/ha). Milk yield per cow and per hectare were significantly increased by the higher rate of fertilizer application (P<0.01) in year 3, but not in years 1 and 2. Mean FCM yields per cow across years were 2574 and 2858 kg from 200 kg N and 400 kg N pastures respectively (P<0.05). The pasture parameters which were most closely correlated with milk yield were green dry matter (GDM) on offer or its components, namely green leaf and green stem. The relations between FCM yield per cow and green dry matter on offer per cow and per hectare were represented by the equations ( � s.e.): Y = 2211 +0.43 (� 0.12) X1 (P<0.01), And Y= 1656 + 0.35 (�0.08) X2 (P<0.01), where Y is FCM yield per cow (kg/lactation), X1 is GDM per cow (kg) and X2 is GDM per hectare (kg). For this environment, it is concluded that a stocking rate of 2.5 cows/ha with 400 kg N/ ha.year can be safely employed to maintain cows on a pure grass pasture from the opening rains in summer until the end of winter.

1976 ◽  
Vol 16 (83) ◽  
pp. 829 ◽  
Author(s):  
RT Cowan ◽  
TH Stobbs

The effect of applying 50 kg N ha-I in autumn and winter each year on milk yield of Friesian cows and dry matter yield and botanical composition of a green panic (Panicum maximum var, trichog1ume)- glycine (Glycine wightii cv. Tinaroo) pasture was measured over two years on the Atherton Tableland, north Queensland. Pastures were grazed at 1.3, 1.6, 1.9 and 2.5 cows ha-1. Milk yield and pasture yield were increased by nitrogen fertilization, particularly at the high stocking rates (P < 0.05). Increases in milk yield from mid-autumn to spring almost totally accounted for increases in annual milk production. Nitrogen fertilizer did not decrease the yield of legume, but legume content of the pasture was reduced in the second year (P < 0.01). Response by non-leguminous species to nitrogen increased (P < 0.05) with stocking rate, a change associated with decreasing legume contents of the pastures. Average fat corrected milk (FCM) yield per cow from mid-autumn to spring was restricted by less than 1600 kg pasture D.M. on offer cow-I or 2500 kg D.M. ha-1. When compared at the same dry matter yields, FCM yield was always higher from nitrogen fertilized pastures than from pastures not recieving fertilizer nitrogen.


1985 ◽  
Vol 25 (3) ◽  
pp. 505 ◽  
Author(s):  
TM Davison ◽  
RT Cowan ◽  
RK Shepherd ◽  
P Martin

A 3-year experiment was conducted at Kairi Research Station on the Atherton Tablelands, Queensland, to determine the effects of stocking rate and applied nitrogen fertilizer on the pasture yield and composition, diet selection by cows, and soil fertility of Gatton panic (Panicum maximum cv. Gatton) pastures. Thirty-two Friesian cows were used in a 4x2 factorial design: four stocking rates (2.0, 2.5, 3.0 and 3.5 cows/ha), each at two rates of fertilizer application 200 and 400 kg N/ha.year. The higher rate of fertilization increased the pasture green dry matter on offer at all samplings (P < 0.01); the increase ranged from 1 106 kg/ha in summer to 548 kg/ha in spring. Green dry matter decreased ( P< 0.0 1) with increasing stocking rate, with mean yields of 3736 and 2384 kg/ha at 2.0 and 3.5 cows/ha, respectively. Weed yields increased over the 3 years at the higher stocking rates for pastures receiving 200 kg N/ha.year. The crude protein content of leaf and stem increased with increasing stocking rate and amount of applied nitrogen fertilizer. Values ranged from 12.1 to 26.5% of dry matter (DM) in leaf and from 3.7 to 13.8% DM in stem. In leaf, sodium concentration (range 0.05-0.20% DM) was increased, while phosphorus concentration (range 0.21-0.44% DM) was decreased by the higher rate of fertilizer application. Plant sodium and phosphorus levels were inadequate for high levels of milk production. Dietary leaf content and crude protein contents were consistently increased by both a reduced stocking rate, and the higher rate of fertilization. Cows were able to select for leaf and at the lowest stocking rate, leaf in the diet averaged 38%; while the leaf content of the pasture was 20%. Dietary leaf content ranged from 38 to 57% in summer and from 11 to 36% in winter. Dietary crude protein ranged from 13 to 15% in summer and from 7 to 11% in winter and was positively correlated with pasture crude protein content and dietary leaf percentage. Soil pH decreased (P<0.05) from an overall mean of 6.3 in 1976 to 6.1 at 200 N and 5.8 at 400 N in 1979. Soil phosphorus status remained stable, while calcium and magnesium levels were lower (P<0.01) after 3 years.


1985 ◽  
Vol 25 (2) ◽  
pp. 241 ◽  
Author(s):  
TM Davison ◽  
WD Jarrett ◽  
P Martin

Milk yields were compared over a 280-day lactation using four patterns of allocation of a fixed amount of grain. Four groups of four Friesian cows grazed a mixed tropical grass (Panicum maximum) and legume (Neonotonia wightii cv. Tinaroo) pasture at 1.1 cows/ha from January to December 1980. The lactation was split into four feeding periods: days 1 - 10,11- 100,10 1 - 190, 191-280. All cows were fed a total of 610 kg hammermilled maize, with 10 kg grain fed during the initial covariate period. The four feeding patterns were: (i) flat rate (FR), where cows received 2.22 kg grain/day; (ii) all early (AE), where cows received 600 kg grain between days 11 and 100; (iii) high early, low late (HELL), where cows were fed 3.5, 2.17 and 1.0 kg/day for periods 11-100,101-190and 191- 280 days of lactation; and (iv) low early, high late (LEHL), where cows were fed in the reverse pattern to HELL. Milk yields per cow over 280 days were 4145, 3942, 3794 and 3630 kg [l.s.d. (P=0.05)= 436 kg] for HELL, FR, LEHL and AE respectively. There was very poor utilization of grain by cows fed AE. The relation between milk yield and grain intake in days 1 1-100 of lactation was described by the equation: Y= 13.9+ 1.77X-0.18X2 (P<0.01, s.e.b1= 0.48, s.e.b2 = 0.06), where Y = milk yield (kg/cow.day) and X = grain intake (kg/cow.day). Apportioning more grain to late lactation, when pasture on offer was low, did not compensate for the loss of milk production in early lactation by cows fed LEHL. Cows fed LEHL lost more liveweight in early lactation than all other treatments, but regained this weight in late lactation. Cows in all treatments had similar liveweights (mean 518 kg) at 280 days. Milk butterfat and solids-not-fat yields over 280 days were not significantly different (P>0.05) for any of the four treatments.


1975 ◽  
Vol 15 (77) ◽  
pp. 740 ◽  
Author(s):  
RT Cowan ◽  
IJR Byford ◽  
TH Stobbs

Forty Friesian cows were grazed continuously on a green panic (Panicum maximum var. trichoglume)/glycine (Glycine wightii cv. Tinaroo) pasture at stocking rates of 1.3, 1.6, 1.9 and 2.5 cows ha-1 for two years on the Atherton Tableland, Queensland. A supplement of 3.6 kg crushed maize cow-1 day-1 was fed for 50 days post-partum to half the cows in each group in both years. Milk yield per cow was reduced from 3811 kg lactation-1 at 1.3 cows ha-l to 3289 kg lactation-1 at 2.5 cows ha-1. With increasing stocking rate milk yield per hectare increased linearly to 8309 kg ha-1 at 2.5 cows ha-1. At 1.9 and 2.5 cows ha-1 cows lost weight over the two years and in late lactation levels of milk solids were often low. Also at these stocking rates cows had to be supplemented for up to 60 days during the main dry season. Legume content of the pasture declined linearly (P < 0.05) with increasing stocking rates. Maize feeding in early lactation increased milk yield over the total lactation by approximately 12 per cent, the response being 2.3 kg milk per kg maize fed, Response was greater at lighter stocking rates as cows in the heavier stocking rate treatments dried off prematurely. It was concluded that per hectare milk production from tropical grass/legume pastures can approach that from temperate pastures and that energy supplementation early in lactation would substantially increase per cow production.


2010 ◽  
Vol 39 (7) ◽  
pp. 1548-1557 ◽  
Author(s):  
Nelson Massaru Fukumoto ◽  
Julio Cesar Damasceno ◽  
Fermino Deresz ◽  
Carlos Eugênio Martins ◽  
Antônio Carlos Cóser ◽  
...  

The objective of this study was to evaluate milk yield and composition, dry matter intake, and stocking rate in pastures with tanzania grass (Panicum maximum cv. Tanzânia), star grass (Cynodon nlemfuensis cv. Estrela-Africana), and marandu grass (Brachiaria brizantha cv. Marandu). The grasses were managed in a rotational grazing system with Holstein x Zebu crossbreed cows, with a 30-day resting period and three days of paddock occupation. The pastures were fertilized with 1,000 kg/ha/year using the 20:05:20 (NPK) formula, split in three applications during the rainy season. It was used a complete random block experimental design with three factors being studied and two replications. In the experiment, four cows/paddock were used and, when it was necessary, regulator animals were added in order to obtain a supply of 7% body weight green forage dry matter. The animals were individually fed concentrate at 2 kg/day during the experimental period. Milk yield did not differ among the three grasses, with values of 9.1; 9.1; and 8.7 kg/cow/day for pastures with tanzania grass, star grass and marandu grass, respectively. Similarly, grass did not affect milk chemical composition. Stocking rate was similar among the three grasses, with values of 4.6; 4.5 and 5.0 UA/ha for tanzania grass, star grass and marandu grass, respectively. The highest dry matter intake was observed for tanzania grass with 2.6% of the body weight while stargrass (2.3%) and marandu grass (2.4%) did not differ among each other. The highest dry matter intake on tanzania grass pasture was not reflected on milk yield per animal. Milk yield and composition and stocking rate are similar among the evaluated grasses.


1969 ◽  
Vol 66 (3) ◽  
pp. 200-222
Author(s):  
J. A. Yazman ◽  
R. E. McDowell ◽  
H. Cestero ◽  
J. A. Arroyo-Aguilú ◽  
J. D. Rivera-Anaya ◽  
...  

Records of milk yield, fat percent, body weight, reproduction and health of 506 calvings of 362 cows were used for estimating the efficiency of utilization of tropical grass pastures by lactating cows fed on grazing alone or grazing with various types of supplement. There were seven feeding systems: grazing alone (T1); grazing plus supplement with ground maize (T2); with molasses (T3); with concentrate (T5); or with urea-molasses (T6), at the rate of 1.0 kg per 2.0 kg milk in excess of 10 kg of milk per day and of 2.5 cows per ha; or grazing plus concentrate feeding of 1.0 kg per 2.0 kg milk irrespective of milk yield at a stocking rate either of 2.5 cows (T4) or 5-0 cows (T7) per ha. All supplement systems had significantly higher yields of milk, fat and fat-corrected milk than grazing alone. Level of fat percent paralleled dependence on intake of forage. Supplement also extended days in milk. System of feeding was significant for body weight gain, time to reach peak milk yield, the level of peak yield, persistency of milk yield, days open, time from first breeding to conception, and calving interval. High levels of supplement (T4, T7) increased weight gains, time to reach peak yield, and persistency, but lowered breeding efficiency. On medium levels (T3, T5, T6), the efficiency (Meal/kg dry matter) of utilization of supplement for milk production was satisfactory, but unsatisfactory on high supplement levels (T4, T7). Supplements as high or higher than those in the grass treatments supplemented with non-protein nitrogen (urea-molasses) or crude protein (concentrate) gave a more efficient utilization than either maize or molasses. During the first 150 days of lactation, cows on grazing alone averaged 14.3 kg pasture grass dry matter intake per day, or 2.9% of body weight. Cows on low supplement (T2, T3, T5, T6) averaged 24 to 29% less; and cows on high supplement, nearly 60% less intake. Type of supplement had little influence on pasture grass dry matter (PGDM) intake. When the genetic potential for milk yield of cows exceeds 3,000 kg, supplementary feeding appears economically feasible. Even under the high levels of nitrogen fertilization employed, there was a rise in average milk yield with intakes of protein from the supplementary feed. Supplementary feeding with tropical grass pastures caused a high rate of substitution; hence, the efficiency of use of PGDM is lowered unless stocking rate is carefully adjusted.


1978 ◽  
Vol 18 (90) ◽  
pp. 12 ◽  
Author(s):  
RT Cowan ◽  
TM Davison

Twenty-four Friesian cows grazing green panic (Panicum maximum var. trichoglume)-glycine (Glycine wightii cv. Tinaroo) pastures at 2 or 4 cows ha-1 were fed no supplement, 2.4 kg maize or 3.0 kg molasses cow-1 day-1. The experiment was a randomized block design and of six months duration. Milk yield and composition were similar for cows fed maize and molasses and these supplements increased average milk yield from 10.3 to 11.8 kg cow-1 day-1 (P < 0.05). Increased stocking rate reduced milk yield from 12.7 to 9.8 kg cow-1 (P < 0.01). Interactions of stocking rate with type of supplement were not significant (P > 0.05). The level of supplement intake and yield of pasture on offer accounted for 52 per cent of the variation in average milk yields (P < 0.01). Of the variation in milk yields between paddocks only 5 per cent was unaccounted for by this relationship.


1981 ◽  
Vol 21 (109) ◽  
pp. 196 ◽  
Author(s):  
TM Davison ◽  
RT Cowan ◽  
PK O'Rourke

Two experiments examined the effect different pasture management strategies had on individual cow milk yield during the summer wet season. In control treatments pasture was continuously grazed. In managed pastures the aim was to produce swards with a high leaf and low stem content. The grasses Panicum maximum cv. Gatton and Brachiaria decumbens were used in both experiments. Experiment one consisted of three pasture treatments; the stock were 1 8 Friesian cows. The control treatment was grazed continuously with no pasture management and was compared with two subjectively applied management treatments in which pasture was either slashed or stocked at variable rates in an attempt to increase pasture quality. The experiment lasted 17 weeks. Each time pastures were slashed or extra cows were added milk yield per cow fell. The lower each grass was slashed or the greater the number of cows added to a paddock the greater the fall in milk yield. Measurements of pasture yield, height and structural composition showed that slashing and variable stocking could increase the leaf percentage in the pasture, but not without seriously decreasing total leaf yield. In experiment two, 24 Friesian cows were used to compare the following treatments over a 10-week period (a) control-continuous grazing, (b) rotational grazing using a 2-week grazing, 2-week spelling regime and (c) rotational grazing with slashing after each grazing period. Milk yields averaged 10.6, 9.8 and 9.6 kg/cow day1, respectively (P> 0.05), and 10.1 and 9.9 kg/cow day-1 for B. decumbens and P. maximum pastures (P> 0.05). As in the first experiment, leaf percentage was increased by management treatments, but not without decreasing total pasture yield to the level where it limited milk production. Leaf yields could only be increased with an associated increase in total pasture yield. It was concluded that grazing management decisions should be based on total pasture on offer rather than any percentage component of total yield.


1993 ◽  
Vol 33 (3) ◽  
pp. 283 ◽  
Author(s):  
WK Ehrlich ◽  
RT Cowan ◽  
A Reid

In a 2-part preliminary experiment, groups of 6 and 9 Holstein-Friesian cows in early t o mid lactation were unsupplemented or supplemented with either 3 kg cracked sorghum grain or 3 kg whole cotton seed on a base pasture of irrigated pangola grass for 12 weeks or oats for 12 weeks. The stocking rate was 5 cows/ha. Supplementation did not affect milk yield or composition. In a second experiment a group of 20 Holstein- Friesian cows in early to mid lactation grazed on a base pasture of subterranean clover at a stocking rate of 4 or 6 cows/ha a n d w e r e either unsupplemented or supplemented with 3 kg of whole cotton seed (WCS) over 12 weeks. Milk yield averaged 20.3 kg/cow.day and there were no significant effects on milk yield or composition. We suggest the lack of a significant milk yield response was due to a high substitution rate of WCS for pasture, associated with an oil content in the diet of 7.1 % of dry matter.


1977 ◽  
Vol 17 (86) ◽  
pp. 373 ◽  
Author(s):  
RT Cowan ◽  
TM Davison ◽  
P O'Grady

Four groups of four Friesian cows grazed green panic (Panicum maximum var. trichog1ume)- glycine (Glycine wightii cv. Tinaroo) pastures at 4 cows ha-1 for 36 weeks from January to October 1975. Cows were individually fed 0, 2, 4 and 6 kg cow-1 day-1 respectively of a maize-soybean meal concentrate. Fat corrected milk (FCM) response to concentrate was linear and was related to the total concentrate intake (X) by the equation, FCM = 1992 + 1.03 X (R.S.D. � 23; P < 0.001) Persistency of lactation decreased with decreasing levels of concentrate feeding (P < 0.01) and lactation length was reduced for cows receiving low levels of concentrates (P < 0.05). Milk fat content was reduced (P < 0.05) and solids-not-fat and casein contents increased by concentrate feeding (P < 0.05). Cows fed 6 kg concentrate cow-1 day-1 were 50 kg cow-1 heavier at drying off than cows fed no concentrate (P < 0.05). Pasture yield on offer to cows was increased linearly with increased concentrate feeding (P < 0.05) and pasture intake by cows was estimated to decrease by 0.9 kg for each kg of concentrate fed (P < 0.05). FCM response to concentrate appeared to increase markedly when pasture on offer fell below 2500 kg DM ha-1. We conclude that FCM response to concentrate will usually be linear for cows grazing tropical pastures, and the size of this response will be strongly influenced by the period of feeding and the yield of pasture on offer to cows.


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