BCS Change Research Articles

Effect of feeding mechanically processed alfalfa silage on production performance of mid-lactation dairy cows

Improving the digestibility and utilization of feedstuffs through processing methods may result in improved production and efficiency of dairy cattle. Our objective was to determine the effect of an intensive mechanical processing technique applied to wilted alfalfa before ensiling on dairy cow performance when fed as part of a TMR. Thirty-six mid-lactation Holstein dairy cows (primiparous and multiparous) were fed diets of similar composition (28.5% alfalfa haylage, 31.2% corn silage and 40.3% concentrates) that differed by pre-ensiling processing technique of alfalfa silage over a 6-week experimental period in a randomized complete block design. Treatments were alfalfa either conventionally chopped (CON) or mechanically processed (MPR). Neither BW, change in BW, BCS nor change in BCS differed between diets. Apparent DM, NDF, ADF, and CP digestibility were greater in MPR compared with CON. The DMI was lesser in MPR compared with CON during wk 5. Furthermore, forage NDF intake was lesser in MPR compared with CON during wk 5. Milk yield did not differ between MPR and CON, but milk fat yield and content were higher in MPR compared with CON. Consequently, 4% FCM and ECM were 1.5 kg/d greater in MPR compared with CON. Gross feed efficiency (ECM/DMI) was greater in MPR compared with CON during wk 5 and 6. Our results suggest that feeding a mechanically processed alfalfa silage enhanced fiber digestibility and subsequently improved dairy cattle gross feed efficiency in mid-lactation dairy cattle by the end of the experimental period. Further research is needed to elucidate physiological responses and practicality of implementing this processing method in a typical production setting.

Assessing supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions

IntroductionBeef cattle in the Northern Great Plains of the United States of America are normally kept in open dry lot pens in winter. Practices such as bale grazing, swath grazing, stockpiling, and corn residue grazing, can be used to extend the grazing season and minimize dry lot use. Extending the grazing season has several advantages over dry lot use but arguably the most important benefit is cost savings due to lower labor and input costs. Strategies selected to supplement cattle in extended grazing systems should maintain cost savings while providing required nutrients to cattle. This study was conducted to evaluate supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions. The study was conducted across variable winter conditions that are encountered in winters in the US Northern Great Plains.MethodsThe study extended over four years. Each year, non-lactating pregnant beef cows (n = 64, year 1; n = 80, year 2, 3, 4) were divided into eight groups of similar average body weight and randomly assigned to one of four bale grazing treatments as follows: a) bale grazing grass hay, b) bale grazing grass hay treated with a liquid supplement, c) bale grazing grass hay and alfalfa hay, and d) bale grazing grass hay and plus 1.8 kg corn DDGS/head/day. Animal performance was assessed from two-day body weights and body condition scores taken at the start and end of the study. Data analysis considered the fixed effects of treatment, year, and treatment x year interaction.ResultsFinal BW tended (P = 0.09) to be greatest following corn DDGS supplementation and lowest when grass hay was offered. The treatment strategy x year interaction (P = 0.026) for ADG showed that corn DDGS supplementation resulted in positive ADG across the years regardless of environmental conditions. Liquid or alfalfa hay supplementation resulted in positive ADG when environmental conditions were favorable. Final BCS (P = 0.005) and BCS change (P = 0.004) were greater following corn DDGS supplementation, intermediate following alfalfa hay or liquid supplementation and lowest when grass hay was fed. Supplementation costs ranged from $1.33 to $1.90/head/day, the highest cost occurred with corn DDGS supplementation mainly due to cost of corn DDGS and labor required to deliver corn DDGS to cattle on pasture.DiscussionAlfalfa hay or molasses-based liquids increased diet CP content but did not supply adequate energy in severely cold winters. Despite relatively higher supplement costs, high energy supplements such as corn DDGS may be required in severely cold winters where cattle require extra energy. Supplement selection should consider supplement effectiveness to meet animal nutrient requirements particularly in adverse winter conditions such as those encountered in the US Northern Great Plains.

Effects of increasing dietary inclusion of high oleic acid soybeans on milk production of high-producing dairy cows

Recent research has highlighted the importance of dietary fatty acid profile of fatty acid supplements on production responses of high-producing dairy cows. Conventional soybeans contain ∼15% oleic acid and ∼50% linoleic acid whereas high oleic acid soybeans (HOSB) contain ∼70% oleic acid and ∼7% linoleic acid. We determined the effect of increasing dietary inclusion of roasted and ground HOSB on production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (50.7 ± 4.45 kg/d of milk; 122 ± 57 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of HOSB at 0, 8, 16, and 24% DM. The HOSB replaced conventional soybean meal and hulls to maintain similar diet nutrient composition (% DM) of 27.4 - 29.4% (NDF), 20.6% forage NDF, 27.5% starch, and 15.9 - 16.5% CP. Total fatty acid content of treatments was 1.65, 3.11, 4.52, and 5.97% DM, respectively. Pre-planned polynomial orthogonal contrasts included the linear, quadratic, and cubic effects of increasing HOSB. Increasing dietary inclusion of HOSB linearly decreased DMI and milk urea nitrogen and increased yields of milk, 3.5% fat corrected milk, energy corrected milk, and milk fat, and quadratically increased milk protein. The increased response to milk fat was due to an increase in preformed milk fatty acids. Due to the increase in milk component yields and decrease in DMI, there was an increase in feed efficiency. Increasing HOSB inclusion linearly decreased plasma BUN concentration and tended to decrease plasma insulin. Increasing HOSB had no effect on BW change or BCS change. In summary, increasing dietary inclusion of HOSB up to 24% DM increased production responses of high-producing dairy cows and did not affect body reserves.

Associations of automated body condition scores at dry-off and through early lactation with milk yield of Holstein cows.

The objective of this study was to analyze the associations of body condition score (BCS) and BCS change (∆BCS) during the dry period and the first 100 d of lactation with daily milk yield. Examining the involvement of health status in the associations between BCS and milk yield was a secondary objective of this research. Data included 12,042 lactations in 7,626 Holstein cows calving between April 2019 and January 2022 in a commercial dairy operation located in Colorado, USA. BCSs were generated daily by an automated BCS camera system located at the exit of the milking parlor. The assessment points selected for this study were dry-off (BCSdry), calving (BCS1), 7 DIM (BCS7), 14 DIM (BCS14), 21 DIM (BCS21), and nadir (nBCS; defined as the lowest daily BCS from calving to 100 DIM). Subsequently, these BCS were categorized considering quartiles (Q1 = 25% lowest BCS; Q4 = 25% greatest BCS), separately for primiparous and multiparous cows. Changes in BCS were calculated from dry-off to calving (multiparous); and from calving to 7 DIM, 14 DIM, 21 DIM, and nadir and assigned into quartile categories considering Q1 as the 25% of cows with the greatest decrease of BCS. Lactations were classified based on the number of health events before nadir as healthy, affected by one event, or having multiple events. Data were examined in primiparous and multiparous cows separately using ANOVA. The least square means for daily milk at 60 DIM and 305 DIM were calculated by category of BCS and ∆BCS at multiple time points and time periods. Subsequently, lactation curves were created by BCS and ∆BCS categories and by health status. Multivariable models included calving season and BCS1 as covariables. The largest differences in milk yield among categories of BCS and ∆BCS were identified for BCS originated at nadir and for the ∆BCS between calving and nadir. The differences in average daily milk yield between cows in the lowest and the greatest nBCS category (Q1 vs. Q4) were 3.3 kg/d (60 DIM) and 3.4 kg/d (305 DIM) for primiparous cows and 2.4 kg/d (60 DIM) and 2.1 kg/d (305 DIM) for multiparous cows. During the period from calving to nadir, primiparous cows in Q1 (greatest decrease of BCS) produced 4.3 kg/d (60 DIM) and 3.8 kg/d (305 DIM) more than cows in Q4. For multiparous cows, the differences were 3.0 kg/d (60 DIM) and 1.9 kg/d (305 DIM) in favor of Q1 cows. Overall, the associations between BCS and ∆BCS categories and milk yield were not consistent across time and they depended on the parity category. Nonetheless, as the assessment of BCS and ∆BCS approached the nadir, the association between greater milk yield and lower BCS or greater reduction in BCS became more evident.

OVULATION SYNCHRONIZATION PROTOCOLS AND FACTORS ASSOCIATED WITH PREGNANCY RATE OF ZEBU FEMALES

<p><strong>Background.</strong> Fixed time artificial insemination is an important tool for the reproductive management of cattle. <strong>Objective.</strong> To determine the effect of two ovulation synchronization protocols and factors associated with the pregnancy rate of Zebu females using fixed time artificial insemination (FTAI) under tropical conditions. <strong>Methodology</strong>. Data of estrous and pregnancy from 129 multiparous Zebu cows and 257 heifers were used. All animals received an intravaginal device (new or used) CIDR<sup>®</sup> or DIB<sup>®</sup>, which remained <em>in situ</em> per 7 days. On the day of device removal, two treatments were established. I) Estradiol cypionate (EC; n = 192): 25 mg prostaglandin F2 alpha and 0.5 mg EC (estradiol cypionate); II) Estradiol benzoate (BE; n = 194): 25 mg PGF<sub>2α</sub> and 24 hours later (day 8), 1 mg BE. Estrous was detected by 1-hour; three times a day, and females inseminated 54-56 hours after removal of device, using thawed semen. Pregnancy diagnosis was by transrectal palpation with real-time ultrasound, 60 days after FTAI. Data were analyzed using Chi-square tests. <strong>Results.</strong> The overall estrous rate was 73.32%. The ovulation synchronization protocol affected the presence of estrous, where EC had a higher rate (79.39%) compared to EB (67.19%). Pregnancy rate for the females inseminated with thawed semen was 54.40%. All factors affected the pregnancy rate (p<0.05). <strong>Implications.</strong> This study provides an alternative for increasing estrous and pregnancy rate of Zebu females, using EC synchronization protocol. It also shows that female type, device and BCS change influence pregnancy rate. <strong>Conclusion</strong>. The highest rate was observed in heifers showing estrous, synchronized with a new intravaginal device, using EC and gaining body condition score.</p>

The effect of a fodder beet versus rye-grass grazing regime during mid-to-late gestation twin-bearing ewes on dam and progeny performance and lamb survival

ABSTRACT The objective was to determine the effect of grazing fodder beet versus ryegrass-dominant pasture from mid-to-late gestation on dam and offspring performance under practical farming conditions. Twin-bearing ewes were randomly allocated to grazing regimes of either fodder beet plus ad libitum ryegrass/clover hay (FB; n = 100) or ryegrass-dominant pasture plus ad libitum ryegrass/clover hay (RG; n = 100) with three replicates per group, from pregnancy day (P) 100–110 to birth. At P135, 10 ewes per treatment were randomly selected from each replicate, slaughtered and back fat and eye muscle depth and fetal body weight and composition were measured. Samples were evaluated for selected blood metabolites. Ewe BW and BCS change and lamb growth were measured, and lamb survival from birth to weaning calculated. Compared with RG, FB ewes had lower ADG and overall lower BCS resulting from increased mobilisation of both fat and muscle. Lambs born to FB-ewes had lower BW and postnatal growth rates and increased mortality from birth to weaning (29% versus 12%). Body composition and blood parameters indicated that FB compared to RG ewes were subject to undernutrition. This study provides new insights into the consequences of FB grazing regimes, as an alternative to ryegrass pasture, on animal performance.

282 The Influence of RFI classification and cow age on body weight and body condition change, supplement intake and grazing behavior of beef cattle winter grazing mixed-grass rangelands

Abstract behavior of beef cattle winter grazing rangelands in North Central Montana. A herd of non-lactating commercial Angus cows, n = 205 (yr-1) and n = 203 (yr-2), ranging in age from 1 to 9 yr old, grazed rangeland pastures (586 ha) from mid-October to early January of 2018 and 2019. Cows were grouped into 6 age classes to evaluate the effects of RFI and age on average daily individual supplement intake, CV of supplement intake, and intake rate, as well as changes in body weight and body condition during an 84-day grazing period each year. Additionally, 30 cows were stratified by age and RFI and fitted with Lotek GPS collars each year to record distance traveled and time spent grazing. Change in cow weight differed by year where cows in yr-1 gained 26.3 ± 1.96 kg while cows in yr-2 lost 19.2 ± 1.96 kg during the 84-day grazing period (P < 0.01). Change in BCS exhibited an age × RFI interaction (P = 0.05); however, an analysis within age groups did not result in differences between RFI classifications (P ≥ 0.27). There was an interaction between RFI, age and year related to supplement intake expressed as g∙kg cow bw-1∙d-1 where in year 2, 4-yr-old high RFI cattle consumed less supplement than 4-yr-old low and average RFI cattle (P < 0.01). Supplement intake rate expressed as g∙min-1 also differed by year (P < 0.01), with cows in yr-1 consuming less supplement per minute than in yr-2 (29.9 ± 1.81 and 91.8 ± 1.87). There were no effects of RFI, cow age or year on time spent grazing (P ≥ 0.19) with cows averaging 6.1 ± 0.61 hrs per day grazing. In summary, cow age had an influence on supplement intake, change in weight and body condition, and grazing behavior, while RFI classification had minimal effects.

PSII-31 Effects of restricted dietary intake on protein expression of oviductal glycoprotein 1 (OVGP1) in the oviductal ampulla of beef cows

Abstract In vitro production of embryos (IVP) results in poor pregnancy rates, with 10 to 40% of embryos transferred surviving to term. Inclusion of oviductal fluid (OF) in the culture media improves success of IVP and pregnancy rates, but factors influencing OF composition are not well investigated. Therefore, we examined the effects of restricted maternal dietary intake on expression of oviductal glycoprotein 1 (OVGP1; or oviductin), a highly conserved glycoprotein involved in fertilization and early embryo cleavage. Multiparous nonpregnant beef cows were randomly assigned to one of 2 intake groups (n = 9 per group) designed to maintain [control (CON)] or lose [0.7 kg/d, negative (NEG)] body weight (BW) for 9 wk; for each cow, initial and final body condition score (BCS; 1–9 scale) and body weight (BW) were determined. Cows were estrus synchronized (Co-Synch + CIDR protocol) and slaughtered 3 d after synchronized ovulation. At slaughter, cross sections of the oviductal ampulla adjacent to the ovary containing the corpus luteum were fixed in neutral buffered formalin, embedded in paraffin, sectioned, and stained using a primary antibody against OVGP1 and fluorescently-labeled secondary antibody. Intensity of immunofluorescent staining for OVGP1 was quantified by image analysis, and differences between intake groups analyzed by t-test. Change (final – initial) in BCS and BW were greater for the NEG compared with CON cows (BCS: -1.06 vs. -0. 50, P< 0.03; and BW: -40.8 vs. -3.6 kg, P < 0.0001). The OVGP1 glycoprotein was expressed in the luminal epithelium of the ampulla, and site of expression did not differ between NEG and CON intake groups. Intensity of staining also did not differ (P >0.30) between NEG and CON intake groups (7.110 vs. 7.153 arbitrary intensity units; SEM = 0.059). Thus, restriction of maternal nutrient intake for 9 weeks did not influence protein expression of OVGP1, a major oviductal glycoprotein.

Predicting the risk of retained fetal membranes and metritis in dairy cows according to prepartum hemogram and immune and metabolic status

Uterine diseases affect a significant proportion of dairy cows, causing significant economic losses. Immune and metabolic statuses are associated with the risk of retained fetal membranes (RFM) and metritis. The hypothesis of this study was that it is possible to use such responses to predict the risk of RFM and metritis. Data from cows (Jersey = 143, Holstein = 116) previously used in four experiments were used. Cow factors [parity, BCS change from −28 to 0 d relative to calving, calf sex, calving problems (twins, stillbirth, dystocia)] were evaluated for their association with the risk of RFM and metritis. Blood samples collected in the last week of gestation were used to measure polymorphonuclear leukocyte phagocytosis, oxidative burst, and expression of CD18 and CD62L, total blood count, haptoglobin optical density, and concentrations of glucose, non-esterified fatty acids, and β-hydroxybutyrate. Cows were treated with egg ovalbumin at −21, −7, and 7 d relative to calving and blood samples were used to determine the anti-ovalbumin IgG optical density. Univariable analyses were carried out to identify variables associated with the risk of RFM and metritis. The significant (P ≤ 0.15) variables were included in multivariable models from which variables with P > 0.15 were removed in a backward stepwise fashion. Risk of RFM was reduced in the absence of calving problems [adjusted odds ratio (AOR) 95 % confidence interval (CI) = 0.13 (0.02, 0.86)], when intensity of phagocytosis [AOR (95 % CI) = 0.50 (0.25, 1.04)] and expression of CD62L [AOR (95 % CI) = 0.71 (0.46, 1.09)] by polymorphonuclear leukocyte were greater, and when prepartum non-esterified fatty acid concentration was lower [AOR (95 % CI) = 8.71 (0.49, 153.84)]. Calf sex [AOR (95 % CI) = 0.35 (0.10, 1.25)], calving problem [AOR (95 % CI) = 0.14 (0.02, 1.08)], PMNL phagocytosis intensity [AOR (95 % CI) = 0.72 (0.47, 1.11)], polymorphonuclear leukocyte intensity of expression CD18 [AOR (95 % CI) = 0.78 (0.60, 1.00)] and CD62L [AOR (95 % CI) = 0.77 (0.60, 0.98)], and haptoglobin optical density [AOR (95 % CI) = 1.16 (0.97, 1.39)] were associated with metritis. Indexes generated from the estimates of the multivariable analyses to predict the risk of RFM [area under the curve = 0.77 (95 % CI = 0.70 to 0.84)] and metritis [area under the curve = 0.76 (95 % CI = 0.70, 0.81)] demonstrated that polymorphonuclear leukocyte function, non-esterified fatty acid concentration, and haptoglobin optical density prepartum may be used as predictors of uterine diseases.

Impacts of feeding a fish-oil based feed supplement through 160 days in milk on reproductive and productive performance, as well as the health, of multiparous early-lactation Holstein cows

A major cause of reproductive failure in contemporary lactating dairy cows is early post-partum negative energy balance (NEB). A strategy to alleviate NEB is to reduce milk energy density by feeding supplements to suppress milk fat synthesis, which could reduce body fat mobilization to favor earlier ovulation and improved pregnancy rates. As fish oils (FO) can cause milk fat depression, and are rich in n-3 PUFA which are beneficial to reproduction, our objective was to evaluate impacts of feeding the FO based feed supplement ‘Optomega Plus’ (OP+) on production, EB, reproduction and health of multiparous Holstein cows through ∼160 days in milk (DIM). Two pens, each of ∼310 multiparous early lactation cows, were fed rations formulated to deliver 0 (C) or 77 g/cow per day of FO (2.53 g/kg DM) as OP+, which contains 3.9 g/cow per day of eicosapentaenoic acid (EPA; C20:5 n-3) and 7.2 g/cow per day of docosahexaenoic acid (DHA; C22:6 n-3). Milk yields and components were recorded monthly for five months after cows were assigned to treatments from a common fresh cow pen at 13.3 ± 0.19 DIM, and body condition (BCS) was scored monthly on a subset of the cows. Dry matter intake (pen basis) was unaffected by treatment, while milk yield, milk components and BCS all had treatment*DIM interactions (P < 0.05), which suggested different responses to the diets before and after ∼130 days post treatment assignment. Feeding OP+ did not impact milk production, but moderately reduced (P < 0.05) milk fat output in the earlier period, which mitigated the NEB as judged by BCS change, but 1st service pregnancy rate was unaffected. There were no treatment impacts on indices of cow health, but feeding OP + improved the healthfulness of the milk FA profile to its human consumers. Results suggest that OP + as a source of FO modestly reduced milk fat output and the extent of early postpartum NEB, without negatively affecting DM intake, health or reproductive performance, while improving the nutritional value of milk fat to its human consumers.

Effects of replacing finely ground corn with whey permeate on the performance of early- and mid-lactation dairy cows

ABSTRACT Objective Our objective was to evaluate the effects of substituting sugar from whey permeate for starch from finely ground corn fed to mid- or early-lactation cows on DMI and milk yield and composition. Materials and Methods Two trials were conducted with 48 Holstein cows in each. In Exp. 1, 48 mid-lactation cows (116 ± 18 DIM) were used in a 10-wk randomized block design. In Exp. 2, 48 early-lactation cows (37 ± 2 DIM) were used in a 12-wk completely randomized design trial. In both experiments, cows were fed a basal diet during a 2-wk preliminary period and then switched to 1 of 3 experimental diets. Whey permeate (WP) was substituted for finely ground corn to provide 0 (CONT), 3.1 (3WP), or 6.1% (6WP) supplement sugar in the rations. Prilled fat was added to maintain NEl concentrations, and proportions of other ingredients were adjusted to maintain similar concentrations of dietary CP and NDF. Intake, milk yield and composition, BW, and BCS were monitored throughout the trial. Results and Discussion The DMI tended to be greater for cows fed WP in Exp. 1, but no differences were observed in Exp. 2. No differences were observed in milk yield or concentration of components in either experiment. Yield of milk protein and solids-not-fat tended to be lower for cows fed diets containing WP compared with CONT. In Exp. 1, dairy efficiency (ECM/DMI) was lower for WP because of the tendency for greater DMI compared with CONT, but no differences in dairy efficiency were observed Exp. 2. No differences were observed in change of BW or BCS in either experiment. Implications and Applications Results of these trials indicate that finely ground corn can be replaced by WP without affecting milk yield and component concentrations, or change in BW and BCS. However, diets containing 6WP tended to reduce yield of milk protein and lactose. Mid-lactation cows had lower dairy efficiency due to a tendency for greater DMI, but DMI and dairy efficiency of early-lactation cows was not affected.

Mineral mixture supplementation for enhancing milk yield of milch animals in Haryana

Most of the Indian soils are deficient in one or more minerals and these minerals are important in numerous biochemical reactions and deficiency may lead to metabolic diseases resulting lowering production performance in dairy animals. The study attempts to evaluate status nutrient intake in dairy animals, effect of reappropriation of available feed resources and mineral mixture supplementation on production performance in lactating cows and buffaloes in Katesara and Amarpur villages under Farmers’ FIRST project in Palwal district. The animals were in their early lactation (40±5 days in milk) and milk yield, its composition, body weight and body condition score was recorded. Among the cow, 28% deficit, 35% excess dry matter; 41% deficit and 11% excess crude protein; 33% deficit and 25% excess total digestible nutrients (TDN) was provided. In buffaloes, 36% deficit and 40% excess DM; 45% deficit and 15% excess CP; 25% deficit and 12% excess TDN was provided. Reappropriation of DM, CP and TDN was done using available feed/ fodders available to the farmers and after 15 days, mineral mixture was provided @ 50 g/d for 60 days. The production performance record reveals no change in body weight but BCS was improved. Milk yield, fat, protein in cows were improved and other composition were remain unchanged. In buffaloes, milk yield, fat and protein improved while others, viz. lactose, SNF, ash and TS were similar due to supplementation of mineral mixture. The results conclude that imbalance of nutrients existed to the tune of 10 to 45% among various nutrients. One of the best propositions could be supplementation of mineral mixture to improve milk yield (10 to 14%) and fat per cent under field condition in both cows and buffaloes.

Association of body condition score with ultrasound backfat and longissimus dorsi muscle depth in different breeds of dairy sheep

• BCS correlates weakly to moderately with backfat thickness in dairy sheep . • Differences up to 0.5 BCS unit exist among breeds at same fat and muscle depots. • Muscle thickness increases at a higher rate than backfat across BCS changes. • Development of a new BCS scale to assess body reserves in dairy sheep is essential.

Effects of diet on body weight, body composition, metabolic status, and physical activity levels of adult female dogs after spay surgery.

Neutering is a risk factor for pet obesity, which reduces the quality and length of life. Dietary interventions may serve as preventive and therapeutic options for pet obesity. The objective of this study was to evaluate the effects of specially formulated diets on body weight (BW), body composition, and blood hormones and metabolites of adult female dogs after spay surgery. All procedures were approved by the University of Illinois Institutional Animal Care and Use Committee prior to experimentation. Twenty-eight healthy adult intact female Beagles (3.02 ± 0.7 yr; 10.28 ± 0.8 kg; body condition score [BCS]: 4.98 ± 0.57) were used in a longitudinal study. Twenty-four dogs were spayed and randomly allotted to one of three experimental diets: 1) moderate-protein, moderate-fiber diet (control; COSP), 2) high-protein, high-fiber diet (HP-HF), or 3) high-protein, high-fiber diet plus omega-3 and medium-chain fatty acids (HP-HF-O). Four dogs were sham-operated and fed the control diet (COSH). Food intake, BW, BCS, blood hormones and metabolites, body composition (via dual-energy X-ray absorptiometry scans), and voluntary physical activity (via Actical devices) were measured over time. After spay, dogs were fed to maintain BW for 12 wk (restricted phase), then allowed to overeat for 12 wk (ad libitum phase). Change from baseline data was analyzed for treatment, time, and treatment × time effects as well as treatment, feeding regimen, and treatment × feeding regimen effects. During the first 12 wk, HP-HF and HP-HF-O had lower (P < 0.01) blood cholesterol than COSH and COSP. During the second 12 wk, HP-HF and HP-HF-O ate more (P < 0.01) food (g/d) than COSH. BCS change for COSP was greater (P < 0.01) than COSH from week 21 to 24, but HP-HF and HP-HF-O were not different. When comparing data by feeding regimen, HP-HF and HP-HF-O had a greater reduction in serum cholesterol (P < 0.001) than COSH and COSP. During the second 12 wk, all spayed dogs consumed more (P < 0.01) food than COSH. However, COSH, HP-HF, and HP-HF-O had a lower (P < 0.001) increase in BCS than COSP. HP-HF-O and COSH had similar serum leptin during weeks 12 to 24. COSP had higher (P ≤ 0.01) serum C-reactive protein than HP-HF-O. Overall, body fat increase in COSP was greater (P < 0.05) than for COSH at week 24, while HP-HF and HP-HF-O were intermediate. Our results indicate that an HP-HF diet can limit weight gain and body fat increase and attenuate serum cholesterol, triglycerides, and leptin concentrations in dogs after spay surgery.

The dynamics of energy supply and demand of foaling mares managed at pasture: a deterministic modelling approach

Context. At pasture, the nutritional status of mares will change due to a dynamic association between their energy requirements and the energy supply. Change in the plane of nutrition can influence reproductive performance measures in the mares. To help optimise nutritional and operational management of mares on stud farms, the nutritional status of Thoroughbred broodmares and the factors influencing the energy supply and demand were investigated. Aims. To assess nutritional status of the Thoroughbred broodmare herds under ‘normal’ New Zealand commercial stud-farm conditions. Methods. The energy intake, energy requirement and energy balance during the last 3 months of pregnancy and the first 5 months of lactation were modelled for mares with an initial bodyweight of 450 kg, 500 kg, 550 kg and 600 kg, and foaled at 0, 15, 50, and 90 days after 1 September. Key results. For all foaling dates and bodyweights, mares were in positive energy balance during the last 3 months of pregnancy (6.1–8.5%). Energy balance decreased as pregnancy progressed, followed by a large and acute energy deficit that was initiated soon after foaling and continued during lactation. The energy deficit during lactation varied between –8.6% and –12.4%, depending on the foaling date modelled. Mares foaling later in the season (50–90 days after 1 September) had greater and longer (30–50 days) postpartum energy deficit than did mares that foaled earlier in the season, who recovered within 20 days postpartum. The modelled changes in the energy balance would be large enough to initiate mobilisation of the fat reserve (body condition), and could, therefore, explain the observation of delayed postpartum to conception interval observed with later-foaling mares on commercial farms. Conclusions. There is a large and prolonged energy deficit soon after foaling and throughout 150 days of lactation in Thoroughbred mares managed under New Zealand commercial grazing conditions. Foaling later in the season can cause a mismatch in energy supply and demand that would increase and prolong the energy deficit. Implications. These findings suggest a need for stud farms to actively manage the pasture supply and monitor the mare’s BWT and BCS changes in an attempt to optimise the mare’s nutritional status and reproductive performance.

Grazing behavior and production characteristics among cows differing in residual feed intake while grazing late season Idaho rangeland.

The objectives were to determine whether cows previously classified during a postweaning test as either low or high residual feed intake (LRFI or HRFI) differed in BW, BCS, and winter grazing activity while consuming poor-quality forage. Thirty Hereford × Angus (LRFI = 16; HRFI = 14) 2-yr-old mid- to late-gestation cows (pregnant with second calf) grazed sagebrush steppe for 78 d beginning 29 September 2015. BW and BCS were collected before and after grazing. Five cows of each RFI classification were fitted with global positioning system (GPS) collars on 16 November 2015 with data collection commencing 3 d later and continuing for 25 d in a 323-ha pasture. The GPS units collected location coordinates every 2 min from which total daily travel distance (DTD) was calculated. Visual counts for bite rate were obtained from collared cows over 8 d. Coordinate data, daily bite rate, BW, and BCS were analyzed as repeated measures using a mixed model, which included RFI group, day, and RFI group × day as fixed effects and cow within RFI group as the random effect. Change in BW and BCS was analyzed by ANOVA with RFI group as the main effect. Cow BCS and BW differed for both day (P < 0.0001) and day × RFI (P < 0.05). Body condition was less (P < 0.05) in LRFI cows at the beginning (5.8 ± 0.13 vs. 6.2 ± 0.14 BCS), but similar (P = 0.67) to HRFI at the end of the study (4.6 ± 0.13 vs. 4.6 ± 0.14). BW among the RFI groups did not differ (P = 0.20) prior to going to range. However, BW-change and BCS-change differed (P < 0.05) between RFI groups. Not only did the LRFI cows lose less BW (-50.0 ± 5.41 kg vs. -66.6 ± 5.78 kg) over the trial, they also were less variable with respect to BW loss. Cows did not differ (P > 0.21) by RFI for DTD or bite rate, but day was significant (P < 0.0001) with cows increasing bite rate as the season of year progressed (55.2 ± 5.63 bites/min for day 4 vs. 84.8 ± 5.32 bites/min for day 21) and increasing DTD as snow storms occurred. Although LRFI cows were leaner than HRFI cows at the commencement of the project, they lost less BW in a late season rangeland environment.

PSX-40 Effects of nutritional plane before breeding on performance of hair sheep

Abstract The objective of the study was to determine effects of the nutritional plane before breeding on performance of different hair sheep breeds. Twenty-five Dorper, 27 Katahdin, and 32 St. Croix ewes with initial BW of 65.6, 65.7, and 54.3 kg (SEM=1.95) and body condition score (BCS; 1–5) of 3.35, 3.29, and 3.09, respectively, consumed wheat straw ad libitum for 11 wk before breeding. Ewes of each breed were divided into four groups, with two groups per nutritional plane (NP). Ewes on a low NP (Low-NP) were supplemented with 0.16% BW (DM) of soybean meal (SBM) and ewes on the high NP (High-NP) received 0.8% BW (DM basis) of 0.25% soybean meal and 0.75% ground corn. Ewes were divided into two groups for estrus synchronization. Four rams of each breed were used, two for the first 17 d of breeding and the other two from d 17 to 34. Conception and embryo mortality were determined by ultrasound imaging at 25 and approximately 40 d post-breeding. Average daily gain and BCS change were similar among breeds, but both were greater for High-NP vs. Low-NP (ADG: 57 vs. -4 g, SEM=8.1; BCS change: 0.22 vs. -0.02, SEM=0.041). Wheat straw DMI was greater (P = 0.01) for Low-NP than for High-NP (2.02 and 1.58% BW, respectively; SEM=0.042) and for St. Croix than for Dorper and Katahdin (P = 0.04; 1.96, 1.68, and 1.74% BW, respectively, SEM=0.060). There were no differences in the number of services or conception (P &amp;gt; 0.05), and no embryo mortality was noted. In conclusion, NP did not influence reproductive performance assessed early after breeding despite differences in ADG and BCS change. This may be due to moderate initial BCS and increased straw intake by Low-NP ewes.

Relationships between body reserve dynamics and rearing performances in meat ewes1.

The main objective of this work was to study the relationships between body reserve (BR) dynamics and rearing performance (PERF) traits in ewes from a Romane meat sheep flock managed extensively on "Causse" rangelands in the south of France. Flock records were used to generate data sets covering 14 lambing years (YR). The data set included 1,146 ewes with 2 ages of first lambing (AGE), 3 parities (PAR), and 4 litter sizes (LS). Repeated measurements of the BW and BCS were used as indicators of BR. The ewe PERF traits recorded were indirect measurements for maternal abilities and included prolificacy, litter weight and lamb BW at lambing and weaning, ADG at 1, 2, and 3 mo after lambing, and litter survival from lambing to weaning. The effects of different BW and BCS trajectories (e.g., changes in BW and BCS across the production cycle), previously been characterized in the same animals, on PERF traits were investigated. Such trajectories reflected different profiles at the intraflock level in the dynamics of BR mobilization-accretion cycles. Genetic relationships between BR and PERF traits were assessed. All the fixed variables considered (i.e., YR, AGE, PAR, LS, and SEX ratio of the litter) have significant effects on the PERF traits. Similarly, BW trajectories had an effect on the PERF traits across the 3 PARs studied, particularly during the first cycle (PAR 1). The BCS trajectories only affected prolificacy, lamb BW at birth, and litter survival. Most of the PERF traits considered here showed moderate heritabilities (0.17-0.23) except for prolificacy, the lamb growth rate during the third month and litter survival which showed very low heritabilities. With exception of litter survival and prolificacy, ewe PERF traits were genetically, strongly, and positively correlated with BW whatever the physiological stage. A few weak genetic correlations were found between BCS and PERF traits. As illustrated by BW and BCS changes over time, favorable genetic correlations were found, even if few and moderate, between BR accretion or mobilization and PERF traits, particularly for prolificacy and litter weight at birth. In conclusion, our results show significant relationships between BR dynamics and PERF traits in ewes, which could be considered in future sheep selection programs aiming to improve robustness.

161 Evaluation of cull sweet potato storage roots as a winter supplement to grazing for cow-calf pairs

Abstract Cull sweet potato storage roots that would otherwise be left unharvested in production fields or dumped as waste from excess supplies in storage may be available for use as livestock feed at competitive pricing relative to other feedstuffs. Given this potential economical source of nutrients for consumption by beef cattle, the objective of this study was to assess cow-calf performance using unprocessed sweetpotato storage roots as a winter supplement to grazing cow-calf pairs as compared to whole cottonseed or no supplement. Fall-calving multiparous Bos taurus crossbred cows in Prairie, MS, were allotted ad libitum access to mixed-grass pasture with tall fescue as the predominant forage species and randomly allocated to one of three as-fed basis supplement groups: 6.8 kg/cow/d of sweetpotato storage roots (SWP); 2.3 kg/ cow/d of whole cottonseed (WCS); or no supplement (NONE). Supplements were offered to cows on a group basis on every Monday, Wednesday, and Friday for 93 d each winter initiating December 5, 2016 (n = 81) and December 11, 2017 (n = 105). Cow BCS on a scale of 1 to 9 (1 = emaciated; 9 = obese) at supplementation initiation was 6.1 ± 0.1. From supplementation initiation until calf weaning in March, change in cow BCS (P &lt; 0.01) was greatest for NONE (-1.1 ± 0.1), intermediate for SWP (-0.7 ± 0.1), and least for WCS (-0.4 ± 0.1). Adjusted 205-d calf BW was 16.9 ± 3.8 kg heavier (P &lt; 0.01) in steers than heifers but did not differ (P = 0.41) among supplementation groups. Although nursing calf performance was not impacted by supplementation regime, results suggest that cull sweetpotato storage roots may be an effective feedstuff for winter supplementation intended to reduce BCS loss in lactating beef cows. Additional research to determine optimal frequency and quantity of SWP supplementation is warranted

An investigation into the factors associated with ewe colostrum production

The majority of lamb mortality which occurs during the first 24 h post-partum is preventable through providing the lamb with sufficient quantities of high quality colostrum during this time. Data from seven late gestation nutrition experiments carried out at this institute between 2002 and 2014 were collated into a single data set comprising of 415 twin bearing ewes. Analysis was carried out to investigate the key drivers of ewe colostrum production excluding nutrient intake, namely body reserve mobilisation, ewe breed type, ewe age, gestation length and lamb birth weight. The volume of colostrum produced at 1 and 18 h post-partum was significantly lower than the volume recorded at 10 h post-partum (P = 0.01). Multivariate regression analysis indicated that colostrum volume during the first 18 h post-partum was influenced by lamb birth weight (P = 0.01), ewe age (P = 0.01), breed type (P = 0. 01) and gestation length (P = 0.06). Live weight change (P = 0.05) also had a significant influence on the volume of colostrum produced but BCS change did not affect colostrum production (P = 0.25). Further multivariate regression analysis indicated that IgG yield was influenced ewe breed type (P = 0.01), lamb birth weight (P = 0.02), gestation length (P = 0.05) and BCS change (P = 0.04). Live weight change (P = 0.12) and ewe age (P = 0.62) did not influence the quantity of IgG produced. Leicester ewes produced less colostrum per kg lamb birth weight at 1 h post-partum compared to all other ewe breed types (P = 0.01) and less than Suffolk ewes at 10 h post-partum (P = 0.01). The result of this analysis shows the key factors excluding ewe nutrition that drive colostrum production. Ewe breed type in particular appears to play an important role in the ability of the ewe to produce sufficient quantities of adequate quality colostrum. In conclusion the result of this analysis highlights the important factors associated with ewe colostrum volume and IgG yield excluding nutrition. In particular the overall structure of the flock such as breed type and ewe age is important when considering the ability of the flock to meet colostrum demands and hence reduce lamb mortality.