scholarly journals High milk production decreases cow-calf productivity within a highly available feed resource environment

2017 ◽  
Vol 1 (1) ◽  
pp. 54-59 ◽  
Author(s):  
S. R. Edwards ◽  
J. D. Hobbs ◽  
J. T. Mulliniks
Keyword(s):  
Pregnancy Rate ◽  
Milk Production ◽  
Milk Yield ◽  
Beef Cows ◽  
Treatment Groups ◽  
Southeastern Us ◽  
Genetic Potential ◽  
Milk Cows ◽  
Calf Performance ◽  
Cow Calf

Abstract The beef cattle industry tends to focus on selecting production traits with the purpose of maximizing cow-calf performance. One such trait is milking ability, which is considered the primary influence on weaning weight of the calf. Therefore, the objective of this study was to determine the effect of actual milk yield on reproductive performance, circulating blood metabolites, and calf performance in beef cows in the Southeastern US. Over a 2 yr period, data were collected from 237, 3- to 9-yr-old Angus-sired beef cows on 3 research stations in Tennessee. On approximately d 58 and 129 postpartum, 24-hr milk production was measured with a modified weigh-suckle-weigh technique using a milking machine. Subsamples of milk were collected for analysis of milk components. Milk yield data were used to retrospectively classify cows on actual milk yield as High ( ≥ 10 kg/d), Mod (8 to 9 kg/d), or Low ( < 8 kg/d). Cow body weight (BW) and body condition score (BCS) were collected weekly at each location through breeding. Calf BW was recorded at birth, mid-weight at d 58, and weaning. At d 58 and 129 of postpartum, milk yields were different (P < 0.001) among the treatment groups. Cow BW during the entire study were not different (P ≥ 0.22) with increasing milk yield. Timed-AI pregnancy rate were the lowest (P = 0.02) in the High milk producing cows with no difference (P > 0.05) between Low and Mod milk cows. In addition, overall pregnancy rate continued to be the lowest (P = 0.04) in High milk producing cows with the greatest pregnancy rate in Mod milk cows. Calf mid-weight at ∼d 58 was increased (P < 0.001) in calves from Mod and High milking cows. However, calf BW at weaning was not different (P = 0.22) among calves from different milk treatment groups. Results from this study suggest that even in management systems that modify the grazing environments with harvested feedstuffs, high milk production decreases reproductive efficiency. In addition, increasing milk production up to d 129 postpartum did not result in increased calf BW at weaning, indicating that the genetic potential for calf BW at weaning could not be improved with increased genetic potential for milk production.

scholarly journals PSII-14 Influence of recent postpartum weight variation on milk production, cow and calf performance and reproductive efficiency of beef cows in Southern Brazil

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 231-232
Author(s):  
Claudia Faccio Demarco ◽  
Marcelo Alves Pimentel ◽  
Cássio Cassal Brauner
Keyword(s):  
Pregnancy Rate ◽  
Milk Production ◽  
Beef Cows ◽  
Southern Brazil ◽  
Weight Changes ◽  
Weight Variation ◽  
Total Milk ◽  
Calf Performance ◽  
Chi Square Analysis ◽  
Peak Lactation

Abstract The objective of this study was to evaluate the influence of the weight changes between calving to peak lactation of range beef cows on the cow and calf performance, milk production and pregnancy rate. Data were collected from 142 primiparous and multiparous beef cows, over a 5-year period. Cows and calves were raised in an extensive range system in Southern Brazil. Cows were divided into two groups according to calving performance and peak lactation. Cows that lost weight (L group, n = 59) and cows that gain weight (G group, n = 83). Milk yield evaluation (weigh-suckle-weigh technique), cow and calf performance were estimated from calving to 189 postpartum days, every 21 days. Cows were subjected to an estrus synchronization protocol and after that, breed by natural service for 45 days. Analysis of variance (ANOVA - GLM) was performed considering effects of the two groups, and pregnancy rates were compared using chi-square analysis. Calves from L cows had greater (P = 0.03) ADG between 21 and 42 days postpartum. However, there was no difference (P > 0.05) in weaning weight. Total milk production was greater (P = 0.01) in L cows. The cows from group G showed a tendency (P = 0.08) to increase pregnancy rate by 15% compared to L cows. In conclusion, cows that gain weight between calving to peak lactation have lower total milk production without any influence in calf performance, and appear to have an increase in pregnancy rate.

Productive longevity of Holstein cows of the Leningrad population with different systems of housing

2021 ◽  
Vol 1 (9) ◽  
pp. 58-67
Author(s):  
O. K. Vasilyeva ◽  
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Great Influence ◽  
Housing System ◽  
Holstein Cows ◽  
Leningrad Region ◽  
Genetic Potential ◽  
Milk Cows ◽  
Calculated Period ◽  
System Factor

To identify the advantages of a tethering system (TS) or loose-housing system (LHS), a comparative analysis of the level of milk productivity and the duration of productive longevity of cows in the Leningrad Region was carried out for a livestock of 4,272 cows that left in 2015–2019. The following indicators were calculated: period of productive use (PPU) – age in days from the first calving to the retirement of the cow, lifetime milk yield (LTMY); milk yield (kg) for 1 milking day, for 1 day of PPU and 1 day of life (Efficiency of Milk Production – EMP) – calculated by dividing lifetime milk yield by the number of milk days, PPU or life. With TS the LTMY is higher by 10,634 kg, which is obtained for 107 additional days of their productive use, milk production for 1 day of milking, the day of use, EMP is higher by 8,2 kg, 6,7 kg and 4,6 kg, respectively, the majority of cows have an EMP level in the ranges of 10,01–15,00 kg of milk (32,0%) and 15,01–20,00 kg (38,2%), and 11,0% of animals have reached an EMP level of more than 20,00 kg of milk. With LHS mainly cows are concentrated in the ranges of 5,01–10,00 kg of milk (43,6%) and 10,01–15,00 kg of milk (46,6%). Desirable cows with LTMY over 30 thousand kg, and in this range, the EMP is almost 10 times higher with TS (43,9 instead of 4,5%). The results obtained cannot be attributed to the advantages of TS. This is confirmed by the great influence of the father on the EMP (factor «Sire» – 0,679) or the inherent genetic potential of productivity, and only by 0,268 system (factor «System of housing») and by 0,296 (factor «Farm») housing conditions on the farm. The «System of housing» influences more on milk yield per 1 day of PPU than on EMP and LTMY (0,342 instead of 0,268 and 0,110, respectively). The effectiveness of LHS is evidenced by the fact that when comparing animals with the same level of EMP under this system, they are used for a longer time and, accordingly, produce more milk per life. So, with a level of 5,01–10,00 kg of milk, cows have a LTMY of 18,1% more with LHS, which were used for 0,54 lactation with PPU for 211 days longer than analogs with TS. A similar trend is observed at the level of 10,01–15,00 kg (+20,8%, +1,17 lact., +461 days) and at the level of 15,01–20,00 kg (+11,3%, +1,18 lact., +499 days). Therefore, for profitable dairy production with a LTMY of more than 30 thousand kg of milk during the PPU of Holstein cows with a LHS, attention should be paid to the level of the inherent genetic potential of productivity (according to the analyzed sample, at least 8000 kg of milk), that is, to select bulls with high breeding qualities.

scholarly journals Influence of post-calving supplemental protein on calf performance and reproductive efficiency for beef cows fed silage

1999 ◽  
Vol 79 (1) ◽  
pp. 97-106 ◽  
Author(s):  
E. Charmley ◽  
J. A. Small ◽  
K. B. McRae
Keyword(s):  
Milk Production ◽  
Body Condition ◽  
Body Condition Score ◽  
Beef Cows ◽  
Negative Energy ◽  
Protein Supplementation ◽  
Linear Effect ◽  
Calf Performance ◽  
Ad Libitum ◽  
Protein Milk

Protein supplementation for winter-calving beef cows between calving and turnout to pasture was studied in two trials. Changes in cow body weight (BW) and condition and calf BW gains were recorded from calving to weaning in the fall. Reproductive performance was monitored, and in trial 2, milk production was determined. In trial 1, multiparous silage-fed cows were allocated to one of five levels of corn gluten meal (CGM): 0, 200, 400, 600 and 800 g d−1. In the second trial, cows were allocated to either restricted or ad libitum silage feeding in combination with three protein supplements: no protein, 400 g d−1 CGM or 475 g d−1 soybean meal (SBM). In trial 1, cows gained weight during supplementation, but on pasture they lost weight (linear effect, P = 0.10). Calf gains and weights at turnout and weaning showed a quadratic response to protein supplementation (P < 0.05). There was a trend toward a linear decline in days to first service with increasing levels of CGM (P < 0.10). In trial 2, cows on restricted silage feeding lost weight (P < 0.05) and body condition (P < 0.10), whereas those fed ad libitum silage gained weight and condition. On pasture, this pattern of weight change was reversed (P < 0.05). Protein supplementation did not influence BW change but tended to cause a lower body condition score at turnout (P = 0.10). Restricting silage intake to the cow did not affect calf performance, but protein supplementation increased gains both during supplementation and on pasture, thus increasing weaning weights (P < 0.05). When silage was fed ad libitum, SBM was more effective than CGM for increasing calf gain. However, when silage was restricted, CGM was more effective. Restricting silage intake did not impair milk production, but feeding CGM increased milk production (P < 0.05). For ad libitum-fed cows, protein supplementation increased pregnancy rate; restricting feed had the opposite effect. Our data suggest that protein supplementation to silage-fed beef cows in good body condition can increase calf performance; however, the level of supplementation is critical, and possible adverse effects on breeding have to be taken into account, particularly with cows in negative energy balance after calving. Key words: Beef cow, protein, milk production, calf gains, silage

A comparison among equations to characterize lactation curves in beef cows

1992 ◽  
Vol 55 (1) ◽  
pp. 23-28 ◽  
Author(s):  
W. D. Hohenboken ◽  
A. Dudley ◽  
D. E. Moody
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Analysis Of Variance ◽  
Beef Cows ◽  
The Other ◽  
Crossbred Cows ◽  
Lactation Curve

AbstractMonthly and fortnightly milk production records were analysed from 59 autumn-calving Angus and Angus × Holstein crossbred cows. Half the cows had been administered 10 mg thyroxine per day from day 60 to 120 of lactation and half were controls. Four published equations to characterize individual lactation curves were compared. These were: (1) log Y(n) = log –a1 + b1log n – c1n (Wood); (2) equation 1 with each log Y(n)2 weighted by Yin)2 (Wood weighted); (3) log [Y(n)/n7 = log l/a3 – k3n(Jenkins); and (4) log Y(n) = a4 – b4n‘(l + 25·5 n’) + c4n2 = d 4/ n (Morant), where Y(n) is milk yield on day n of lactation, n' is n–110 (the mid point of lactation), and the a, b, c, k and d parameters are estimated from solution of the equations. The lactation curve from the Jenkins equation projected peak milk yield to occur some 30 days later than estimates from the other equations. It underestimated production early and late in lactation and overestimated it during mid lactation. For several cows, the Morant equation projected that peak production occurred at the end of lactation. Also, analysis of variance of milk production variables was less sensitive when the traits were estimated by the Morant equation than when they were estimated by one of the others. The Wood weighted equation resulted in estimates of peak day of lactation and peak yield that were less variable and more realistic than estimates from the Wood equation. Collectively, therefore, the Wood weighted equation was deemed most suitable to characterize variability among and within these beef cows in milk production. All four equations, however, ranked the 59 cows similarly for estimated 220-day yield.

Influence of a short-term prepartum supplementation on beef cows and calves’ performance in pastoral conditions

2016 ◽  
Vol 56 (11) ◽  
pp. 1913 ◽  
Author(s):  
G. Quintans ◽  
A. Scarsi ◽  
G. Roig ◽  
M. Carriquiry ◽  
G. Banchero
Keyword(s):  
Milk Production ◽  
Postpartum Period ◽  
Crude Protein ◽  
Beef Cows ◽  
Breeding Period ◽  
Serum Progesterone ◽  
Follicle Diameter ◽  
Acid Detergent Fibre ◽  
Calf Performance ◽  
Sorghum Grain

Multiparous Aberdeen Angus × Hereford crossbred cows were used to evaluate the effect of supplementation during the last month of gestation on milk production and composition and cow and calf performance. Cows were assigned randomly to supplement (SUP; n = 18) or Control (CON; n = 17) treatments. Supplemented cows were offered (1 kg/100 kg bodyweight) a mix of sorghum grain and protein concentrated (67 : 33 as-fed basis; 16% crude protein, 11% acid detergent fibre) from (mean ± s.e.m.) 33 ± 1.4 days prepartum until calving. Before, during, and after the supplementation period, cows grazed together a native pasture paddock with average forage mass available of 1345 kg/ha of dry matter (10.4% crude protein, 45.2% acid detergent fibre). Cows were blood sampled weekly from –42 to 112 days postpartum (DPP) for serum progesterone and non-esterified fatty acids (NEFA) concentrations. Maximum follicle diameter was measured by ovarian ultrasound examination at 60 DPP. The breeding period lasted 60 days and started at 60 ± 1.4 DPP. There was an interaction between treatment and time on BCS (P < 0.0005). Before calving there were no differences in BCS between cows in SUP and in CON, but at calving SUP cows tended (P = 0.10) to present greater BCS and from calving to 84 DPP BCS was greater (P < 0.05) in SUP with respect to CON cows. There was an interaction between treatment and time on plasma NEFA concentrations (P < 0.0005). During the last month of gestation NEFA concentrations were reduced in SUP cows but there were no differences between treatments during the postpartum period. Milk production decreased linearly from 30 to 150 DPP but there was no effect of treatment on it. Calf bodyweight at birth and at weaning did not differ between treatments (37.5 ± 2.4 and 175.6 ± 2.4 kg, respectively). The probability of cows presenting follicles with diameter ≥10 mm was greater (P < 0.05) in SUP than CON cows. The length of the postpartum period did not differ between treatments. The probability of cows cycling during the first 90 DPP and pregnancy rate tended (P = 0.08) to be greater in SUP than in CON cows. Supplementation in winter and for only 30 days in the last month of gestation of beef cows under grazing conditions, increased cows’ BCS without increasing BW of calves, and tended to improve reproductive performance.

scholarly journals Performance Efficiency of Pasture-raised Primiparous Beef Cows of Three Different Biotypes and Two Milk Production Levels

2017 ◽  
Vol 45 (1) ◽  
pp. 8
Author(s):  
Jaqueline Schneider Lemes ◽  
Marcelo Alves Pimentel ◽  
Ricardo Zambarda Vaz ◽  
Lucas Balinhas Farias ◽  
Cássio Cassal Brauner
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Pregnancy Rate ◽  
Milk Production ◽  
Beef Cows ◽  
Nutritional Requirements ◽  
Beef Production ◽  
Total Milk ◽  
Production Group ◽  
Heavy Group

Background: Productivity and efficiency of beef production systems should be estimated based on cow size, calf growth rate and cow reproduction rate, which are critical factors for the evaluation of production characteristics of beef cattle of different biological types. One of the ways to measure beef cow productivity is based on the ratio of calf weaning weight to cow weight. The purpose of this study was to evaluate the performance and reproductive efficiency of primiparous beef cows of three different biotypes and two milk production levels, from calving to weaning, in pasture-raised beef systems. Materials, Methods & Results: Forty-two primiparous Angus cows were classified according to body weight at calving, as follows: Heavy (431 kg); Medium (388 kg); and Light (348 kg). Cow efficiency as a function of biotype was evaluated at two different moments: calving and weaning, based on the ratio of calf weight to cow weight*100 (in kilograms). Calf production efficiency was determined based on the ratio of calf weaning weight (CWW) to cow pregnancy rate (PR), resulting in the calf production index = kg of weaning calves per cow (CWW*PR/100).  The experimental design was a completely randomized factorial 3 x 2 x 2 design (three biotypes x two calf sexes x two milk production levels). The results were subjected to ANOVA and F-test. The Light and Medium cow groups produced more (P < 0.05) kilograms of calf per kilogram of cow (16.0 and 15.1 kg, respectively) than the Heavy group (14.0 kg). Light cows showed lower (P < 0.05) milk production and, as a result, lighter (P < 0.05) calves at weaning (151.9 ± 4.3 kg) than Medium and Heavy groups, 166.0 ± 3.7; 166.5 ± 4.0 kg, respectively. At beginning of the breeding season, cows of the Lower milk production group were on average 27.49 kg heavier than cows in the Higher milk production group. There was an interaction (P < 0.05) between total milk production and calf sex on characteristics of performance in calves and performance efficiencies of the system. Light and Medium cows showed 51 and 25 kg total weight gain from calving to weaning, corresponding to 14.7 and 6.4% of body weight, respectively. The Heavy group, however, showed a 3 kg loss (0.5% of body weight) during the same period. Discussion: A higher growth rate was observed in the pre-weaning period of the calves of heavy cows; as a result, these calves were heavier at weaning. To achieve this result, heavier cows may compensate this higher nutritional requirement using body reserves. This biological adjustment may not be economically efficient, since the subsequent reproduction of these cows could be impaired by increases in milk production. Therefore, the target cow in a pasture-raised beef system is one whose low nutritional requirements enable her to produce milk, resulting in heavier calves, and whose physiological conditions enable her to conceive again during the breed season. Light cows can be considered an efficient group, since their pregnancy rate enabled them to create a positive difference for the group, notwithstanding their lower milk production and lighter calves (P < 0.05) at weaning.  This tendency is expected, since increased growth rates are associated with a decrease in puberty and early finishing age. It is essential to select animals according to their efficiency in order to reduce the cow’s requirements, since this favors the increased productivity of cows of lower maintenance cost in relation to their body weight, leading to higher biological and economic efficiency in the beef production system. In conclusion, because of their lower nutritional requirements, cows of small and moderate biotypes and lower total milk production are more efficient than cows of larger biotypes and higher milk production in pasture-raised beef systems.

9 EFFECT OF TIMING OF INSEMINATION WITH SORTED SEMEN ON SUBSEQUENT PREGNANCY RATE IN POSTPARTUM BEEF COWS SYNCHRONIZED WITH A MODIFIED 14-DAY PROGESTERONE PROTOCOL

2014 ◽  
Vol 26 (1) ◽  
pp. 119
Author(s):  
A. J. Davis ◽  
J. G. Powell ◽  
T. D. Lester ◽  
R. W. Rorie
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Prostaglandin F2α ◽  
Beef Cows ◽  
Subsequent Pregnancy ◽  
Pregnancy Rates ◽  
Treatment Groups ◽  
Rate Analysis ◽  
Chi Squared ◽  
Pregnancy Status

A study investigated the effect of AI timing on pregnancy rate when using X sorted semen, and whether prostaglandin F2α (PGF2) injection on Day 7 of a modified 14-day progesterone (P4) protocol improved oestrous response in beef cows. Angus-based cows were allotted across treatment groups by cyclicity, parity, weight, body condition, and days postpartum. Treatment 1 (n = 132) cows received a CIDR P4 insert (Eazi-Breed CIDR, Pfizer Animal Health, Groton, CT, USA) on Day 0, with CIDR removal on Day 14, followed by 100 μg of gonadotropin-releasing hormone (GnRH; Factrel, Pfizer) on Day 16, and 25 mg of PGF2 (Lutalyse, Pfizer) on Day 23. Treatment 2 (n = 132) cows received the same synchronization treatment, except for an additional 25 mg dose of PGF2 given on Day 7 of CIDR treatment. Cows were observed for oestrus over an 84-h period and inseminated with X-sorted semen at 9 to 14, 15 to 17, 18 to 21 or 22 to 24 h after detected oestrus, followed 10 days later by exposure to fertile bulls for 45 days. Ultrasonography was used to determine pregnancy status ~45 days after AI and again 45 to 55 days after bull removal. Chi-squared analysis was used to determine the effects of treatment on oestrus response, AI pregnancy, and seasonal pregnancy rates, and the effect of AI timing on pregnancy rate. Analysis of variance was used to determine the effects of treatment on the interval from PGF2 dosing to detected oestrus. Oestrus response to synchronization treatment was similar (P = 0.33) at 76.5 and 71.2% for cows in Treatments 1 and 2, respectively. The mean interval from PGF2 to the onset of oestrus was extended (P = 0.03) ~3 h for cows in Treatment 2 (57.4 v. 54.3 h, respectively). About two-thirds of the cows in each treatment were cyclic at the start of synchronization. The extended interval from PGF2 to observed oestrus was due to an effect on cyclic, but not acyclic, cows in Treatment 2. Of the cows expressing oestrus, 69 and 89% expressed oestrus 48 to 72 h post-PGF2 in Treatments 1 and 2, respectively. Pregnancy rates after AI with sorted semen were similar (P = 0.64) at 63.3 and 66.7% for Treatments 1 and 2, respectively. No differences (P = 0.98) were detected in AI pregnancy rates for insemination intervals ranging from 9 to 24 h after detected oestrus. At the end of the breeding season, seasonal pregnancy rates were also similar (P = 0.74), at 83.3 and 84.9% for cows in Treatments 1 and 2, respectively. The addition of a PGF2 treatment on Day 7 of our 14-day CIDR-based protocol was expected to ensure all cows has sub-luteal P4 concentrations and would develop a persistent follicle capable of ovulation in response to GnRH given on Day 16. Whereas the Day 7 PGF2 treatment had no effect on oestrus response or pregnancy rate, it did result in a more synchronous oestrus within a 24-h period. Results indicate that acceptable pregnancy rates can be achieved in lactating beef cows when using sorted semen over a range of insemination times.

Determinant Factors of Cow’s Milk Production in the Mountain Area

2017 ◽  
Vol 11 (1) ◽  
pp. 15-23
Author(s):  
Roger Catalin Manea
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Total Duration ◽  
Main Criterion ◽  
Statistical Parameters ◽  
Mountain Area ◽  
Genetic Potential ◽  
Milk Cows ◽  
Data Tables ◽  
Milk Level

Abstract The production of milk, the quantity of fat respectively constitute the main criterion of assessment of dairy cows in the mountain area and downhill. The average performance in the succession of eight lactations per total lactation is 3420.67 kg, and per normal lactation is 3209.20 kg milk. The limits vary between 1506 kg of milk and 8835 kg milk recorded for lactation and 1506 kg of milk and 7322 kg milk for normal lactation. The study of statistical parameters of index of the total duration of lactation allows us to affirm that the cows from the herd studied have the genetic potential to increase lactation beyond the limits of normal lactation of 305 per days. Milk production per day is higher with + 0.45 kg per total lactation than normal lactation. Extension of lactation and breast resting shortening represents loss of milk production in both current lactation and the next lactation. To estimate the effect of localities was used the analysis of variance within samples. Raw data tables have been processed to create tables of variances between herds of the 6 localities and within the herd in each locality. The influence of the locality on the milk production is null. The output production of milk cows has as enablers: daily output and duration of lactation on her. The raise of the productive cows milk level in the mountain area and hence income breeders is achievable through the integration and expansion of biotechnology.

scholarly journals Management strategies to improve cow-calf productivity on meadow bromegrass pastures

2004 ◽  
Vol 84 (3) ◽  
pp. 529-535 ◽  
Author(s):  
J. C. Kopp ◽  
K. M. Wittenberg ◽  
W. P. McCaughey
Keyword(s):  
Milk Yield ◽  
Average Daily Gain ◽  
Management Strategies ◽  
Beef Cows ◽  
Fertilizer Application ◽  
Milk Composition ◽  
Low Protein ◽  
Cow Calf ◽  
Meadow Bromegrass ◽  
The Cost

A 4-yr experiment was conducted to determine the effects of fertilization, incorporation of a legume and use of the Rumensin®-controlled release capsules (CRC) on productivity of cow-calf pairs grazing meadow bromegrass (Bromus biebersteinii Roem & Schult.). Four pasture treatments (T), alfalfa-grass fertilized (AF), alfalfa-grass unfertilized (AU), grass-only fertilized (GF) and grass-only unfertilized (GU), each replicated twice were compared. The eight 3.7-ha pastures were split into five equally sized paddocks and rotationally stocked with first-calf cows in 1995 and 1998, and with mature cows in 1996 and 1997. Half of the cows on each pasture received a Rumensin® CRC 1 wk prior to the start of the pasture season. Cow DMI was not influenced by fertilization or incorporation of a legume. However, cows treated with monensin consumed less (2.3% BW) compared to the control cows (2.5% BW, P < 0.05). Incorporation of alfalfa and fertilization improved pasture quality and resulted in higher CP and lower NDF content in forage selected by the animals. Monensin improved (P < 0.05) cow average daily gain (ADG, kg d-1) when grazing unfertilized grass and alfalfa-grass pastures, but did not influence gains of cows on fertilized pastures. Fertilizer application, legume incorporation and monensin administration did not affect milk yield or milk composition. Despite differences in diet quality, calf ADG for AU, AF, and GF were similar. However, calf ADG was lower for GU pastures (P < 0.05), probably as a result of the high fibre and low protein content of this pasture treatment. Both incorporation of alfalfa and fertilization increased total calf gain (kg ha-1); the greatest improvement was associated with fertilization. There were, however, economic advantages to legume incorporation, as the cost of the additional gain for GF and AF pastures averaged $1.08 and $0.79 kg-1 ha-1, and no extra costs were incurred for AU. Key words: Beef cows, calves, milk yield, pasture productivity, alfalfa, meadow bromegrass

The composition of body-weight changes in underfed lactating beef cows

1981 ◽  
Vol 32 (1) ◽  
pp. 95-103 ◽  
Author(s):  
P. R. N. Chigaru ◽  
J. H. Topps
Keyword(s):  
Body Weight ◽  
Milk Production ◽  
Milk Yield ◽  
Deuterium Oxide ◽  
Tritiated Water ◽  
Body Weight Loss ◽  
Beef Cows ◽  
Weight Changes ◽  
Weight Losses ◽  
Unit Body Weight

ABSTRACTThe effects of reducing the feed intake of 12 winter-calving (Hereford male × British Friesian female) cows to the maintenance level for 6 weeks from week 10 of lactation were investigated during two consecutive lactation periods. Initially, six cows were in their first and six in their third lactation. In each year the period of ‘underfeeding’ was preceded by a period of ‘adequate feeding’ (maintenance plus milk production requirements) and succeeded by a period of ‘refeeding’ (2 × maintenance). Changes in body water, estimated by the dilution of tritiated water and deuterium oxide at the end of each feeding period, were used to calculate changes in body tissue. Milk yield during the period of ‘adequate feeding’ indicated that individual cows differed markedly in milk production potential. During ‘underfeeding’ milk yield was related to lactation potential. Cows of higher potential tended to maintain higher yields than those of lower potential but in doing so they incurred higher body-weight losses. The ‘refeeding’ period did not result in significant increases in milk yield. The weight losses during ‘underfeeding’ consisted mainly of fat but some cows apparently mobilized relatively large amounts of protein. More fat per unit body weight loss was mobilized by the heifers than by the cows, which, on the other hand appeared to mobilize relatively more protein. On ‘refeeding’, only a few cows were able to achieve complete tissue repletion.

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