Browsing by Subject "Fertility"

Now showing 1 - 4 of 4
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    Comparison of 2-breed crossbred cows sired by Montbeliarde and Viking Red compared with pure Holstein cows during first lactation in high-performance Minnesota dairy herds
    (2017-12) Loeschke, Amy
    Background Dairy producers have interest in crossbreeding because crossbred cows have enhanced fertility and survival compared to Holstein (HO) cows, leading to more profitability. This research study was designed to compare the phenotypic performance of Montbeliarde (MO) × Holstein and Viking Red (VR) × HO crossbred cows with pure HO cows in large, high-performance dairy herds. Methods All cows were either 2-breed crossbred or pure HO cows that calved for the first time from December 2010 to April 2014. Best Prediction was used to calculate 305-d milk, fat, and protein production as well as SCS, and 513 MO × HO, 540 VR × HO, and 978 HO cows were analyzed for production during first lactation. Body condition score (BCS) and conformation were subjectively scored once during early lactation by trained evaluators. The analysis of survival to 60 d in milk included 536 MO × HO, 560 VR × HO, and 1,033 HO cows during first lactation. Cows analyzed for other fertility, survival, and conformation traits had up to 13% fewer cows available for analysis. Results Age at first calving was similar for breed groups, and the herds calved both crossbred (x̅ = 23.8 mo) and HO (x̅ = 23.9 mo) cows at young ages. The MO × HO crossbred cows had +3% higher production of 305-d fat plus protein production (actual basis, not mature equivalent) than the HO cows during first lactation, and the VR × HO were similar to the HO cows for fat plus protein production. Breed groups did not differ for SCS during first lactation. The VR-sired 3-breed crossbred calves (from MO × HO dams) were similar to pure HO calves for calving difficulty (CD) at first calving; however, MO-sired male calves born to VR × HO dams had a mean score that was +0.5 points higher for CD than pure HO male calves. The 3-breed crossbred calves from both MO × HO (4%) and VR × HO (5%) first-lactation dams had much lower stillbirth (SB) rates compared with pure HO calves (9%) from first-lactation dams. The first service conception rate of the crossbred cows (both types combined) increased 7%, as did the conception rate across the first 5 inseminations, compared with the HO cows during first lactation. Furthermore, the combined crossbred cows (2.11 ± 0.05) had fewer times bred than HO cows (2.30 ± 0.05) and 10 fewer d open compared with their HO herdmates. Across the herds, breed groups did not differ for first-lactation survival to 60 d in milk; however, the superior fertility of the crossbred cows allowed an increased proportion of the combined crossbreds (71 ± 1.5%) to calve a second time within 14 mo compared with the HO cows (63 ± 1.5%). For survival to second calving, the combined crossbred cows had 4% superior survival versus the HO cows. The MO × HO and VR × HO crossbred cows both had increased BCS (+0.50 ± 0.02 and +0.25 ± 0.02, respectively), but shorter stature and less body depth than HO cows during first lactation. The MO × HO cows had less set to the hock and a steeper foot angle than the HO cows, and the VR × HO had more set to the hock with a similar foot angle to the HO cows. The combined crossbred cows had less udder clearance from the hock than HO cows, more width between teats both front and rear, and longer teat length than the HO cows; however, the frequency of first-lactation cows culled for udder conformation was uniformly low (< 1%) across the breed groups. Conclusions The high-performance herds in this study experienced superior fertility and survival with no loss of production during first lactation for 2-breed crossbreds compared to pure HO cows. The fertility and survival of cows are very influential on lifetime profitability. The first-lactation results from this study suggest MO × HO and VR × HO 2-breed crossbred cows may have increased lifetime profit than pure HO cows in high-performance dairy herds. A comparison of the lifetime profitability and, also, profitability of the subsequent generations of crossbred cows for this rotational crossbreeding system versus pure HO cows warrants further examination.
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    The effects of family planning type and prevalent use on fertility and under-five mortality in Tanzania.
    (2012-05) Ghiselli, Margherita Emilia
    Current projections estimate that the population of Tanzania will triple by 2050, reaching 110 million. Voluntary family planning (FP) is the best strategy to curb population growth. However, contraception availability varies across regions. This study accounts for the regional context in which contraceptive choices -- and reproductive outcomes -- occur. Its research question, then, is: what is the effect of the regional context on total fertility rate and under-five mortality rate? This study employs the 2010 Tanzania Demographics and Health Survey (DHS), a representative probability sample of 10,139 women ages 15 to 49. To mimic randomization, regions are matched on education, wealth, and urban-rural status, and assumed to be exchangeable save for their exposure to an FP method. The region-level independent effect of a specific FP method on total fertility rate and under-five mortality rate is calculated for different types of FP methods (i.e., oral contraceptives, injectables, condoms, sterilization, traditional methods). Also, population projections are re-calculated for incremental prevalence of each method. Only permanent methods significantly reduce the total fertility rate, with an average causal effect of -1.59 children (-2.55, -0.65). Indeed, they alone guarantee the end of reproductive events. No method significantly reduces under-five mortality. Population growth trends would be most impacted by oral contraceptives (from 40 million in 2010 to 33 million in 2025 if prevalence increases by 19%), followed by injectables (42 million in 2025 with 19% prevalence increase). This difference is due to continued use of oral contraceptives through a woman's twenties and thirties, while injectables are mostly used by women in their twenties. These results suggest that sterilization immediately impacts on a region's total fertility rate. However, long-term investments in oral and injectable contraceptives will have a significant impact reducing population growth, and should be given funding priority.
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    Essays on the Microeconomics of Development in Tanzania
    (2016-05) McCarthy, Aine
    This dissertation contributes to a growing body of research on the microeconomics of development in Sub-Saharan Africa. Fertility, labor market participation and agriculture are key components of the microeconomic development process in Tanzania. I explore household and individual decisions in all three of these domains in Tanzania through economic analysis and impact evaluation. Both experimental and non-experimental impact evaluations improve the public understanding of what works in economic development. For the first essay in Chapter 2, I explore household fertility decisions by estimating the effect of a community family planning education program on fertility behavior in the Meatu District. In Chapter 3, I investigate the effects of an entrepreneurship training program on financial literacy and employment attitudes in the Kagera region. In Chapter 4, I analyze the impact of polygyny on agricultural productivity in farming households across the country.
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    Montbeliarde-sired crossbreds compared with pure Holsteins for feed intake, production, fertility, survival, and body measurements
    (2013-05) Hazel, Amy Renae
    Crossbreeding was initiated in two institutional herds of the University of Minnesota in 2000. Montbeliarde (MO)-sired progeny of pure Holstein (HO) and Jersey × HO crossbred (JH) cows along with pure HO cows calved for the first time from 2005 to 2010 in both herds.Montbeliarde (MO)-sired crossbred cows (n = 57) were compared with pure Holstein (HO) cows (n = 40) for dry matter intake (DMI), production, hip height, body condition score (BCS), and body weight (BW) during the first 150 d of first lactation. Also, production for 305 d was compared for first lactation. This subset of cows from the larger crossbreeding study were housed at the University of Minnesota St. Paul dairy and calved from 2005 to 2007. The MO-sired crossbred cows were composed of MO × HO cows (n = 33) and MO × Jersey/HO cows (n = 24). Cows were individually fed a total mixed ration twice daily. The DMI was measured for the first 150 d of lactation, except DMI was not recorded from d 1 to 3 postpartum to permit cows to acclimate to stalls in a confinement barn. Hip height was measured once between 20 and 172 d postpartum, and BCS and BW were recorded every other week. The MO-sired crossbred cows did not differ from the pure HO cows for 150-d DMI, 150-d fat plus protein production, or for 305-d fat plus protein production. Hip height was similar for MO × HO and pure HO cows, but MO × Jersey/HO cows had shorter hip height than the pure HO cows. Despite the lack of difference for DMI, the MO-sired crossbred cows had significantly greater BCS (3.30 vs. 2.74) and BW (551 kg vs. 528 kg) than the pure HO cows. The MO-sired crossbred cows (122 d) had fewer days open than the pure HO cows (150 d). The higher BCS of the MO-sired crossbred cows, especially during early lactation, may have provided an advantage for fertility. Differences for DMI between breed groups were not studied for the latter half of first lactation or for multiparous cows.Subsequently, Montbeliarde (MO)-sired crossbred cows (n = 150) were compared with pure Holstein (HO) cows (n = 163) for production, somatic cell score (SCS), fertility, survival to subsequent calving, mortality, and body measurements during their first five lactations. The MO-sired crossbreds cows consisted of MO × HO cows (n = 59) and MO × (Jersey/HO) cows (n = 91) and were housed in either a high-input, confinement herd (St. Paul) or a low-input, grazing herd (Morris). Body, hoof, and udder measurements of cows were objectively measured. The MO × HO crossbred cows were not different for fat plus protein production during any lactation and had significantly lower SCS during second lactation compared with the pure HO cows. However, the MO × (Jersey/HO) crossbred cows had 5% lower fat plus protein production with similar SCS compared with pure HO cows at St. Paul. On the other hand, the MO × (Jersey/HO) crossbred cows were not different for fat plus protein production and had lower SCS in third to fifth lactation compared with pure HO cows at Morris. Across herds, the MO-sired crossbred cows had 41 fewer days open and 12% higher pregnancy rate compared with the pure HO cows. Furthermore, the MO-sired crossbred cows (8%) had lower mortality rates than the pure HO cows (18%). Because of superior fertility and lower mortality rates, the MO-sired crossbred cows had greater survival to second (+13%), third (+24%), fourth (+25%), and fifth (+17%) calving in comparison to pure HO cows. For body measurements, MO × HO were similar to pure HO cows for hip height and heart girth, but MO × HO cows had more body condition and greater body weight than pure HO cows during first (+39 kg), second (+80 kg), and third to fifth (+39 kg) lactations. The MO × (Jersey/HO) had more body condition but shorter hip height than pure HO cows, and this resulted in less body weight across the first five lactations. The additional body condition of MO-sired crossbred cows may likely provide an advantage for fertility. Foot angle was steeper and hoof length was shorter for MO × HO cows, but MO × (Jersey/HO) cows were similar to pure HO cows for hoof measurements. The MO-sired crossbred cows had 3.6 cm less udder clearance and 2.6 cm greater front teat width than pure HO cows.